Sludge from sea-based Atlantic salmon (Salmo salar L.) production: quantification, composition, and potential application in IMTA

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Krogli, Kjell Inge Reitan This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3969754/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 7 You are reading this latest preprint version Abstract Future growth of Atlantic salmon ( Salmo salar L.) in Norway is tied to finding solutions for major ecological challenges connected to salmon lice, escapees, and nutrient emissions from sea cages. At the same time, nutrient-rich sludge from salmon production comprises a valuable resource for the cultivation of lower trophic species using an integrated multi-trophic aquaculture (IMTA) approach. This study aimed to quantify the sedimentation of waste sludge under sea cages of an Atlantic salmon aquaculture site and to qualify the composition of this sludge. Additionally, the study evaluated the potential use of sludge from sea-based aquaculture as a feed source for polychaetes Hediste diversicolor . Using sediment traps, sludge samples were collected from two different sea cages, at two different depths, and three different sampling dates. Subsequently, they were quantified, and their composition was assessed with regards to carbon, nitrogen, phosphorus, lipid, fatty acid, protein, amino acid, and ash content as well as elemental ratios and composition of fatty acids and amino acids. The quantity of collected sludge was significantly different between sea cages, with a strong positive correlation between feed input and collected sludge. Sampling depth did not affect the quantity of collected sludge. No significant difference in the proportion of sedimented sludge as a proportion of theoretically produced sludge was found when comparing the different cages and sampling depths. Further, the composition of collected sludge was similar at all sampling points. The overall nutritional value was lower compared to sludge from land-based aquaculture, regardless, sludge from sea-based salmon production can in theory be considered as a potential feed resource to be used for the production of polychaetes H. diversicolor . Atlantic salmon salmon aquaculture aquaculture sludge nutrient dispersal lipids fatty acids amino acids Figures Figure 1 Figure 2 Figure 3 1 Introduction Global aquaculture production is increasingly gaining significance, given that the production has doubled in the last 20 years and quadrupled in the last 30 years (FAO, 2022 ). Norway is the world's largest producer of Atlantic salmon ( Salmo salar L.), with a total production volume of 1.52 million tonnes in 2023 (Shahbandeh, 2020 , Fiskeridirektoratet, 2024a ). A production of this magnitude entails ecological challenges connected to salmon lice, escapees, and nutrient emissions from sea cages (Lekang et al., 2016 , Olaussen, 2018 ). These nutrient emissions are directly linked to the use of feed as up to 62% of carbon (C), 57% of nitrogen (N), and 76% of phosphorus (P) contained in the salmon feed are not utilized by the fish and thus released into the environment in the form of feed loss, feces production, excretion, and respiration (Wang et al., 2012 , Wang et al., 2013 ). Based on a feed consumption of 1.94 million tonnes reported in 2023 (Fiskeridirektoratet, 2024b ), and an approximate content of 49% C, 6% N, and 1.5% P in feed (Olsen et al., 2008 ), the calculated nutrient release from Norwegian salmon production in 2023 amounted to 588,000 tonnes C, 66,000 tonnes N, and 22,000 tonnes P. With a projected fourfold production by 2050, these numbers will correspondingly increase in the years to come (Olafsen et al., 2012 ). Waste generated by salmon farms can be categorized into three groups: particulate organic matter (POM), dissolved organic matter (DOM), and dissolved inorganic matter (DIM) (Sæther et al., 2013 ). POM consists of particulate organic carbon (POC), particulate organic nitrogen (PON), and particulate organic phosphorus (POP) that originate from feed waste and feces and can serve as a nutrient source for organisms in water masses and benthic environments (Troell et al., 2009 ). DOM are small molecules and particles that are resuspended from uneaten feed and feces; it is made up of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and dissolved organic phosphorus (DOP) (Fredriksen et al., 2011 ). DOM represents a minor fraction of the overall waste but is made up of stable substances with a prolonged turnover time that enters the microbial food web (Sæther et al., 2013 ). DIM consists of nutrients released into the water by fish through excretion and respiration. These nutrients are utilized by phytoplankton in the euphotic zone and macroalgae in the littoral zone (Olsen and Olsen, 2008 , Husa et al., 2014 ). While the ecological effects of DOM and DIM are difficult to quantify, a monitoring program, following the Norwegian standard 9410, has been developed to quantify the effects of POM originating from salmon aquaculture on benthic habitats (Standard Norge, 2016, Lovdata, 2023 ). This standard consists of different types of analyses which include the B- and C-investigation. The B-investigation is a mandated trend monitoring for marine fish farming facilities in Norway which is carried out on site at regular intervals. It assesses seabed conditions beneath aquaculture facilities, utilizing a handheld grab for a qualitative evaluation based on three main categories: the presence of fauna, chemical condition, and sensory condition. The frequency of the B-investigation varies based on prior trend monitoring results, with poor conditions prompting more frequent assessments (Fiskeridirektoratet, 2023a ). In 2021, 91% of the B-investigations performed at aquaculture sites scored either “good” or “very good” (BarentsWatch, 2023 ). The C-investigation is a comprehensive soft-bottom survey designed to evaluate the impact of aquaculture facilities on the adjacent seafloor. It extends outwards from the aquaculture site and surrounding waters, measuring sediment chemistry, composition, and benthic fauna. The investigation aims to identify the origin of organic material, determining whether it comes from the aquaculture facility or other sources in the vicinity (Fiskeridirektoratet, 2023b ). In 2015–2016, ca. 90% of surveyed aquaculture sites scored either “good” or “high” in the C-investigation (Fiskeridirektoratet, 2016). Results from C-investigations and literature show that different polychaete species are often found in high abundance beneath sea cages as they thrive in the organically enriched marine environments created by uneaten feed, fish feces, and other organic matter that accumulates in the sediment (Tomassetti and Porrello, 2005 , Bannister et al., 2014 , Valdemarsen et al., 2015 ). Using an integrated multi-trophic aquaculture (IMTA) approach, previous studies have given promising results for the application of polychaetes for recycling in waste sludge from salmon aquaculture, both from sea cages (Nederlof et al., 2019 , Nederlof et al., 2020 ) and land-based production (Wang et al., 2019a , Anglade et al., 2023b ). Hereby, the species Hediste diversicolor has been focused on in several publications since it has not only been demonstrated to efficiently utilize nutrients contained in waste sludge but could also serve as a potential feed resource to be used in aquafeeds (Fidalgo e Costa et al., 2000 , Bischoff et al., 2009 , Wang et al., 2019b , Wang et al., 2019a ). The presented study aimed to quantify sedimentation of waste sludge directly under sea cages and assess the composition of this sludge. The potential use of this sludge from sea-based salmon aquaculture was evaluated as a feed source for polychaetes in an IMTA context. Hereby, the hypotheses were that 1) different salmon cages at the same aquaculture site will have a different quantity of sedimented sludge, depending on feed input, 2) the sludge quantity that sediments to the seafloor will be lower than directly beneath the cages, 3) the composition of sludge will not be affected by cage location at the farm or sampling depth, and 4) sludge that sediments from sea-based salmon aquaculture can be used as a resource for cultivation of polychaetes H. diversicolor . 2 Material and methods 2.1 Collection of sludge Sediment traps were used for the collection of sludge from salmon cages and at a reference site in August 2022. Sludge collection was conducted at two salmon sea cages (hereafter referred to as “Cage 1” and “Cage 2”, respectively) at the aquaculture site "Lamøya" (site no. 12993, Måsøval AS), situated outside Sistranda in Trøndelag county, Norway (63°43'59.0"N, 8°51'17.9"E). Sludge from the aquaculture site was collected at three samplings points (n = 3), for 48 h at each sampling. As a reference site, a location approximately 3.5 km away and beyond the influence of any aquaculture sites was chosen (63°45'6.3"N and 8°55'15.9"E). Sample collection at the reference site ran for 7 days to accumulate sufficient material for analyses. The water depth at all sampling sites was approximately 50 m. The total cage depth of the salmon cages was 39 m. According to data obtained from Måsøval AS, at the time of sludge sampling, Cage 1 held 105 372 ± 300 fish with an average weight of 896 ± 28 g, giving a total biomass of 94.42 ± 2.67 tonnes, whereas Cage 2 held 75 012 ± 331 fish with an average weight of 853 ± 40 g, giving a total biomass of 63.99 ± 2.76 tonnes. The feed used during the sampling period was RAPID HP 500 50A (7 mm, EWOS AS); salmon in Cage 1 were fed 642 ± 206 kg d − 1 (DW), those in Cage 2 received 647 ± 144 kg d − 1 (DW) in the two days prior to the samplings. The sediment traps consisted of 4 PVC tubes, with a removable cup at the bottom of each tube. At each salmon cage, six traps were attached to the floating collar of the cage; three traps were placed right beneath the cage at 39 m depth (“Top (T)”) and three traps were placed close to the seafloor at 44 m depth (“Bottom (B)”). At the reference site, three sets of traps that were attached to buoys were deployed at the same depths as those at the salmon cages (39 m and 44 m). After the sampling period, the sediment traps were retrieved and transported to the feed barge. There, the traps were left for 5 min to allow for the sample material to settle on the bottom of the trap. Excess seawater was removed from the PVC tubes using a pump that was equipped with a 300 µm filter on the inlet and a 200 µm filter on the outlet to avoid any accidental pumping of sample material. Approximately 100 mL seawater containing the sampling material were left in the sampling tube. The cups holding the rest of the seawater and the sample were then detached from the sediment trap. The content of four tubes that make up one sediment trap was transferred into sampling bottles and frozen at -20°C. In preparation for further analyses, samples were centrifuged for a total of 15 min at 5000 rpm, using a Sorwall RC-5C Plus centrifuge for 5 min, and a Heraeus Labofuge 400R (both Thermo Fisher Scientific, USA) for an additional 2 x 5 min. Subsequently, samples were freeze-dried, and the dry weight was recorded (balance: XA204DR, Mettler Toledo, Switzerland). From each salmon cage, the samples from the three sediment traps at the same depth were pooled after drying, which gives the four different sampling groups: Cage 1 – Top (“C1T”), Cage 1 – Bottom (“C1B”), Cage 2 – Top (“C2T”), and Cage 2 – Bottom (“C2B”). From the reference site, samples from the three top traps and the three bottom traps, respectively, were pooled for quantification of sample material. For chemical analyses, all samples from the reference site were pooled. 2.2 Chemical analyses Samples from the sediment traps at the salmon farm and the reference site were analyzed for their C, N, and P content, elemental ratios, and ash content. Samples from the salmon farm were further analyzed for total lipid content, fatty acid (FA) content and composition, amino acid (AA) content and composition, and protein content. Ash content was measured by combustion of samples in a muffle furnace at 450°C for 5 hours. C and N were examined via gas chromatography in an organic elemental analyzer (Vario EL Cube, Elementar Analysensysteme GmbH, Germany) with acetonitrile as the reference standard. P was oxidized using potassium peroxydisulfate, as outlined in the methodology by Koroleff ( 1976 ). Subsequently, quantitative analysis of phosphate content was conducted photometrically using an autoanalyzer (Flow Solution IV, O.I Analytical) following NS-EN ISO 6878. The elemental ratios of C:N, C:P, and N:P were calculated based on the respective C, N, and P content (mg g − 1 DW). Lipids were extracted with chloroform (CHCl 3 ) and methanol (CH 3 OH) (2:1 v/v) following Folch et al. ( 1957 ) and subsequently gravimetrically quantified. Following lipid extraction, FAs were hydrolyzed and esterified to fatty acid methyl esters with methanol, and then analyzed by means of gas chromatography (7890B GC, Agilent Technologies, USA) equipped with helium carrier gas, a WCOT fused-silica capillary column coated with CP-wax 52CB (Holger CP7713) and a flame ionization detector (FID). AAs were analyzed according to Šližytė et al. ( 2017 ). Samples were hydrolyzed at 110°C in 6 M HCL containing 0.4% mercaptoethanol for 24 h, followed by filtration using Whatman glass microfiber filters (grade GF/C, 47 mm). The pH was subsequently adjusted to 2.2 and the samples were then separated through a high-performance liquid chromatography (HPLC) system (Agilent Infinity 1260, Agilent Technologies, USA), which was coupled to an online post-column derivatization module (Pinnacle PCX, Pickering Laboratories, USA). Protein content was calculated by summation of water-free AAs. 2.3 Quantification of sludge collection and dispersal The collected sample material at the two different depths at each of the salmon cages and the reference site were quantified, and the amount of sludge that sedimented at each depth at the aquaculture site was calculated by extrapolation of the trap area to the total cage area. $${m}_{sedimented sludge}=\frac{{A}_{cage}}{{A}_{traps}}*{m}_{collected sludge}$$ Where m sedimented sludge (kg DW d − 1 ) is the calculated mass of sedimented sludge for the whole cage, A cage (m 2 ) is the cage area, A traps (m 2 ) is the combined area of all three sediment traps at each depth, and m collected sludge (kg DW d − 1 ) is the mass of collected sludge that was recorded in our experiment. The four PVC tubes that made up one sediment trap had an inner diameter of 6.50 cm each, giving a total area of 132.73*10 − 4 m 2 per trap. The total collection area A traps , consisting of three traps at each depth, was 398.20*10 − 4 m 2 . The total salmon cage area is defined by the circumference of the cages of 120 m, giving a cage area A cage of 1145.92 m 2 . The mass of collected sludge m collected sludge was calculated by deducting the mass of sample material (kg DW d − 1 ) collected at the reference site from the mass of sludge (kg DW d − 1 ) collected under the salmon cages for each sediment trap to adjust for naturally occurring POM. The theoretical production of sludge (kg DW d − 1 ) was quantified based on Aas and Åsgård ( 2017 ), where the assumption is made that 87% of supplied salmon feed (DW) is ingested, meaning 13% remain uneaten. The ingested feed has an apparent digestibility of 70%, while 30% of ingested feed will be defecated. Based on these numbers, the total theoretical sludge production, which is made up of uneaten feed and feces, will be 39.1% of supplied feed (kg DW d − 1 ). The sedimented proportion was calculated by dividing the mass of theoretically produced sludge (kg DW d − 1 ) by the mass of sedimented sludge (kg DW d − 1 ). 2.4 Statistical analysis Statistical analyses were carried out using Sigmaplot for Windows Version 14.0 (Systat Software, Inc., USA). Minitab® 21.1 (Minitab, LLC) was used for principal component analysis (PCA) of FA and AA composition of sludge samples collected at the salmon farm. Normal distribution of data was assessed using Shapiro-Wilk tests, and homogeneity of variance was examined using Brown-Forsythe tests. For the comparison of two groups, Welch's t-test was employed. In cases where the data did not follow a normal distribution, log transformation was applied or a non-parametric test, the Mann-Whitney Rank Sum Test for two-group comparisons, was used. Results from sludge sample qualification, namely, ash, lipid, FA, protein, AA, C, N, and P content, as well as elemental ratios, percentages of saturated FAs (SAFAs), monounsaturated FAs (MUFAs), polyunsaturated FAs (PUFAs) and percentages of essential AAs (EAA) and non-essential AAs (NEAAs) were compared at the two different depths at the same cage (C1T vs. C1B and C2T vs. C2B) and the same depth at the two different cages (C1T vs. C2T and C1B vs. C2B). Additionally, C, N, and P content of samples at the reference site was compared with those from the salmon cages. Results from qualification of fish feed were compared with sludge samples using one-way analysis of variance (ANOVA) followed by pairwise multiple comparisons using the Holm-Sidak method. As for sample quantification, C1T vs. C2T and C1B vs. C2B were analyzed for significant differences in the percentage of sludge that was collected. Further, linear regression analysis was conducted to display the relationship between salmon feed supplied and sludge collected under the salmon cages. All statistical analyses were carried out at the 95% confidence level (p < 0.05). 3 Results 3.1 Quantification of sedimented sludge Feed input and the correlated theoretical production of sludge at the two different salmon cages varied between sampling dates (Table 1 ). A similar mass of sludge (kg DW d − 1 ) was collected right under the salmon cages (Top) and on the seafloor (Bottom) on all sampling dates at both cages. There was no significant difference in the sedimented proportion (%) when comparing different depths at the same cages and the same depths at different cages (C1T vs. C1B and C2T vs. C2B) (Welch’s t-test, p ≥ 0.05). Linear regression analysis found a strong positive correlation (R 2 = 0.98, p < 0.05) between the feed supplied to the salmon and the sludge that was collected by the sediment traps (Fig. 1 ). Table 1 Feed input (kg DW d -1 ), theoretically produced sludge (kg DW d -1 ), sedimented sludge (kg DW d -1 ), and sedimented proportion of sludge (%) from sediment traps below Atlantic salmon sea cages, right under the cages (Top) and on the seafloor (Bottom). Cage no. Date Feed input (kg DW d − 1 ) Theoretically produced sludge (kg DW d − 1 ) Trap position Sedimented sludge (kg DW d − 1 ) Sedimented proportion (%) Cage 1 11.08. 433.60 169.54 Top 29.04 17.13 Bottom 23.35 13.77 17.08. 645.54 252.40 Top 39.09 15.49 Bottom 38.99 15.45 24.08. 846.37 330.93 Top 36.25 10.95 Bottom 33.55 10.14 Cage 2 11.08. 485.42 189.80 Top 20.21 10.65 Bottom 22.38 11.79 17.08. 692.27 270.68 Top 35.92 13.27 Bottom 32.18 11.89 24.08. 763.54 298.54 Top 37.75 12.64 Bottom 36.07 12.08 3.2 Biochemical composition of reference site samples, sludge samples from the salmon farm, and fish feed C content (mg g − 1 DW) of samples collected under the salmon cages was similar at the same depth at different cages (C1T vs. C2T and C1B vs C2B) and different depths at the same cage (Welch’s t-test, p ≥ 0.05, Table 2 ). Further, all samples from the salmon cages had a significantly higher C content than samples collected at the reference site (one-way ANOVA, p < 0.05). The C content of fish feed was significantly higher than that of the sludge samples (one-way ANOVA, p < 0.05). N content (mg g − 1 DW) of sludge samples was similar at different depths and different cages (Welch’s t-test, p ≥ 0.05), and not different from the reference samples (one-way ANOVA, p ≥ 0.05). Fish feed had a significantly higher N content than sludge samples (one-way ANOVA, p < 0.05). No difference in P content (mg g − 1 DW) of samples collected under the salmon cages was found between the different sampling groups (Welch’s t-test, p ≥ 0.05). However, sludge samples had a significantly higher P content than reference samples (one-way ANOVA, p < 0.05), with sludge samples containing 13–18 times as much P as samples at the reference site. The P content of fish feed was not significantly different from that of sludge samples (one-way ANOVA, p ≥ 0.05). The C:N ratio of sludge samples was similar at different depths and different cages (Welch’s t-test, p ≥ 0.05), and significantly higher than that of samples collected at the reference site (one-way ANOVA, p < 0.05). A significantly lower C:N ratio of fish feed compared to sludge samples was found (one-way ANOVA, p < 0.05). There was no significant difference in C:P ratio of sludge samples when comparing sampling groups (Welch’s t-test, p ≥ 0.05), and all sludge samples had a significantly lower C:P ratio than reference samples (one-way ANOVA, p < 0.05). The C:P ratio of fish feed was significantly higher than that of sludge samples (one-way ANOVA, p < 0.05). The N:P ratio was similar for all sludge samples (Welch’s t-test, p ≥ 0.05), while the N:P ratio of reference samples was significantly higher (one-way ANOVA, p < 0.05). Fish feed had an N:P ratio that was significantly higher than that of sludge samples (one-way ANOVA, p < 0.05). Table 2 Carbon (C), nitrogen (N), and phosphorus (P) content (mean ± SD, mg g − 1 DW), and C:N, C:P, and N:P ratios (-) of sludge collected from sediment traps below Atlantic salmon sea cages, Cage 1 – Top, Cage 1 – Bottom, Cage 2 – Top, and Cage 2 – Bottom (n = 3), sediment traps from a reference site (n = 3), and fish feed (n = 3). Asterisks denote significant differences from the reference site and x denotes a significant difference of fish feed from sludge samples. Cage 1 – Top Cage 1 – Bottom Cage 2 – Top Cage 2 – Bottom Reference site Fish feed Carbon (mg g − 1 DW) 197.02 ± 35.12 * 183.56 ± 53.62 * 212.12 ± 56.37 * 209.16 ± 60.59 * 115.17 ± 7.83 454.21 ± 17.57 x Nitrogen (mg g − 1 DW) 8.63 ± 1.73 8.22 ± 2.58 7.79 ± 2.17 7.74 ± 3.49 9.51 ± 1.19 65.96 ± 3.4 x Phosphorus (mg g − 1 DW) 20.44 ± 5.5 * 16.89 ± 7.1 * 23.47 ± 9.32 * 18.35 ± 7.48 * 1.29 ± 0.12 14.23 ± 0.26 C:N (-) 23.06 ± 2.98 * 22.91 ± 5.06 * 27.82 ± 6.3 * 30.39 ± 10.28 * 12.20 ± 1.08 6.90 ± 0.59 x C:P (-) 10.03 ± 1.92 * 11.42 ± 1.83 * 10.28 ± 4.81 * 11.98 ± 2.87 * 89.89 ± 8.26 31.94 ± 1.78 x N:P (-) 0.45 ± 0.13 * 0.54 ± 0.24 * 0.39 ± 0.21 * 0.44 ± 0.19 * 7.46 ± 1.34 4.63 ± 0.16 x Ash content (mg g − 1 DW) of sludge samples was similar across sampling groups and not significantly different from samples at the reference site (Welch’s t-test, p ≥ 0.05, Table 3 ). The ash content of fish feed was significantly lower than that of sludge samples (one-way ANOVA, p < 0.05). No difference between sludge samples at different depths or different cages was found for the content of protein and lipid (mg g − 1 DW), while fish feed had a significantly higher protein and lipid content than sludge samples. The content of unidentified material (which includes carbohydrates) (mg g − 1 DW) was not significantly different between sludge samples (Welch’s t-test, p ≥ 0.05) and when comparing sludge samples with fish feed (one-way ANOVA, p ≥ 0.05). Table 3 Composition (mean ± SD) of sludge collected from sediment traps below Atlantic salmon sea cages, Cage 1 – Top, Cage 1 – Bottom, Cage 2 – Top, and Cage 2 – Bottom (n = 3), sediment traps from a reference site (n = 3, ND = no data), and fish feed (n = 3). x denotes a significant difference of fish feed from sludge samples. Cage 1 – Top Cage 1 – Bottom Cage 2 – Top Cage 2 – Bottom Reference site Fish feed Ash (mg g − 1 DW) 476.48 ± 109.2 507.18 ± 79.99 461.16 ± 106.68 472.04 ± 133.8 658.93 ± 13.04 82.74 ± 0.952 x Protein (mg g − 1 DW) 62.67 ± 18.93 70.54 ± 3.68 71.42 ± 17.62 67.42 ± 20.04 ND 366.39 ± 19.37 x Lipids (mg g − 1 DW) 97.05 ± 30.42 92.82 ± 22.8 125.54 ± 27.18 127.93 ± 45.83 ND 241.93 ± 15.62 x Unidentified material (mg g − 1 DW) 363.8 ± 62.6 329.47 ± 61.47 341.88 ± 62.59 332.62 ± 68.8 ND 308.94 ± 18.74 x Amino acids (mg g − 1 DW) 73.26 ± 22.19 82.52 ± 4.23 83.74 ± 20.6 79.02 ± 23.4 ND 426.16 ± 22.44 x Fatty acids (mg g − 1 DW) 56.04 ± 21.71 53.91 ± 14.26 80.11 ± 17.78 86.19 ± 33.88 ND 225.64 ± 13.44 x The total AA content (mg g − 1 DW) of sludge samples was not significantly different at different depths or different cages (Welch’s t-test, p ≥ 0.05), fish feed, however, had a significantly higher AA content than all sludge samples (one-way ANVOA, p < 0.05, Table 3 ). The sludge samples at different depths or at different cages showed no significant differences for the relative content of ΣEAA (% of total AAs) (Welch’s t-test, p ≥ 0.05, Table 4 ). Further, no difference was detected for ΣNEAA content (% of total AAs). A significantly lower proportion of EAA and a significantly higher percentage of NEAA was found when comparing fish feed with sludge samples (one-way ANVOA, p < 0.05). Leucine, phenylalanine, and lysine were the EAAs with the largest proportions in sludge samples. In fish feed, leucine, lysine, arginine, and phenylalanine were the most abundant EAAs. Of the NEAAs, glutamic acid + glutamine, alanine, serine, and aspartic acid + asparagine had the largest share of total AA, both in sludge samples and fish feed. PCA revealed that relative AA composition (% of total AAs) of sludge samples was not affected by the position at the farm (Cage 1 or 2) or the water depth at which they were taken (Fig. 2 ). Differences in variance of AA composition were smaller between the different sludge samples than when comparing sludge samples to fish feed. Together, PC1 and PC2 explained 67% of the variance in AA composition. Table 4 Relative amino acid (AA) composition (% of total AAs) of sludge collected from sediment traps below Atlantic salmon sea cages, Cage 1 – Top, Cage 1 – Bottom, Cage 2 – Top, and Cage 2 – Bottom (n = 3) and fish feed (n = 2). EEAs = essential AAs, NEAA = non-essential AAs. x denotes a significant difference of fish feed from sludge samples. Cage 1 Top Cage 1 Bottom Cage 2 Top Cage 2 Bottom Fish feed Total AAs (mg g − 1 DW) 73.26 ± 18.12 82.52 ± 3.46 83.74 ± 16.82 79.02 ± 19.11 426.16 ± 22.44 x % of total AAs Arginine 3.19 ± 0.61 3.07 ± 0.29 3.87 ± 0.56 3.11 ± 0.32 6.54 ± 0.28 Histidine 2.36 ± 0.18 2.35 ± 0.16 2.74 ± 0.52 2.20 ± 0.24 2.16 ± 0.02 Isoleucine 6.50 ± 0.68 6.77 ± 0.82 6.34 ± 0.28 6.18 ± 0.18 4.41 ± 0.03 Leucine 9.19 ± 0.78 9.02 ± 0.67 9.49 ± 0.48 8.83 ± 0.52 7.62 ± 0.03 Lysine 4.60 ± 0.43 4.61 ± 0.50 4.20 ± 0.22 4.54 ± 0.15 6.96 ± 0.19 Methionine 2.52 ± 0.31 2.35 ± 0.48 2.40 ± 0.08 2.15 ± 0.19 2.08 ± 0.06 Phenylalanine 8.00 ± 0.51 7.74 ± 0.79 7.76 ± 0.26 7.41 ± 0.43 4.66 ± 0.07 Threonine 4.55 ± 0.29 4.63 ± 0.04 4.58 ± 0.47 4.50 ± 0.09 3.16 ± 0.07 Tryptophan - - - - - Valine 6.64 ± 0.17 6.19 ± 0.10 6.50 ± 0.06 6.26 ± 0.16 5.09 ± 0.09 ΣEAAs 47.55 ± 0.58 46.73 ± 1.42 47.88 ± 0.91 45.18 ± 0.70 42.69 ± 0.70 x Alanine 7.29 ± 0.31 7.37 ± 0.44 7.53 ± 0.67 7.95 ± 0.57 5.68 ± 0.02 Aspartic acid + Asparagine 5.76 ± 0.25 6.58 ± 0.71 6.58 ± 0.51 6.55 ± 0.29 6.53 ± 0.17 Cysteine (Cys-Cys) 2.44 ± 0.27 2.00 ± 0.50 2.13 ± 0.25 1.95 ± 0.25 1.56 ± 0.10 Glutamic acid + Glutamine 9.12 ± 0.76 9.93 ± 1.74 8.54 ± 0.36 8.53 ± 0.41 21.27 ± 0.52 Glycine 5.70 ± 0.36 6.12 ± 0.50 5.63 ± 0.57 5.58 ± 0.61 4.12 ± 0.05 Proline 6.28 ± 1.33 6.73 ± 0.94 7.25 ± 1.25 8.97 ± 1.45 8.26 ± 0.44 Serine 7.51 ± 1.01 7.31 ± 0.69 7.48 ± 0.14 7.83 ± 0.16 6.41 ± 0.21 Taurin 0.16 ± 0.16 0.12 ± 0.09 0.40 ± 0.11 0.24 ± 0.10 0.08 ± 0.02 Tyrosine 5.65 ± 0.43 4.97 ± 0.58 5.39 ± 0.26 4.98 ± 0.19 3.18 ± 0.08 Methionine sulfoxide 0.22 ± 0.11 0.20 ± 0.13 0.17 ± 0.09 0.31 ± 0.14 0.04 ± 0.02 Hydroxyproline 1.36 ± 0.66 1.83 ± 1.11 0.87 ± 0.57 1.35 ± 0.60 0.09 ± 0.02 Hydroxylysine 0.96 ± 0.58 0.13 ± 0.02 0.13 ± 0.10 0.59 ± 0.32 0.10 ± 0.09 ΣNEAAs 52.45 ± 0.58 53.27 ± 1.42 52.12 ± 0.91 54.82 ± 0.70 57.31 ± 0.70 x The total FA content (mg g − 1 DW) of sludge samples taken at different depths and different cages was not significantly different from each other (Welch’s t-test, p ≥ 0.05, Table 3 ). Fish feed had a significantly higher FA content than sludge samples (one-way ANOVA, p < 0.05). No differences were detected in relative content of ΣSAFAs, ΣMUFAs, and ΣPUFAs (% of total FAs) when comparing sludge samples from different depths and different cages (Welch’s t-test, p ≥ 0.05, Table 5 ). The proportion of SAFAs in fish feed was significantly lower compared to sludge samples, while the proportion of PUFAs was significantly higher (one-way ANOVA, p < 0.05). The proportion of MUFAs contained in fish feed was not significantly different from that in sludge samples (one-way ANOVA, p ≥ 0.05). The FAs with the largest proportions in both sludge and fish feed were oleic acid (C18:1 n-9), linoleic acid (C18:2 n-6), palmitic acid (C16:0) and stearic acid (C18:0). There were no differences in percentages of arachidonic acid (ARA; C20:4 n-6), eicosapentaenoic acid (EPA, C20:5 n-3), and docosahexaenoic acid (DHA, C22:6 n-3) between the sludge samples from different depths and different cages. The percentage of EPA and DHA in fish feed was significantly higher than in sludge samples, while the proportion of ARA was not significantly different. PCA showed that relative FA composition (% of total FAs) of sludge samples was not affected by sampling depth. However, it was impacted by the position of the cages at the farm to some extent (Fig. 3 ). Differences in variance of FA composition were smaller between the different sludge samples than when comparing sludge samples to fish feed. PC1 and PC2 combined explained 79% of the variance in the FA data set. Table 5 Relative fatty acid (FA) composition (% of total FAs) of sludge collected from sediment traps below Atlantic salmon sea cages, Cage 1 – Top, Cage 1 – Bottom, Cage 2 – Top, and Cage 2 – Bottom (n = 3) and fish feed (n = 2). SAFAs = saturated FAs, MUFAs = monounsaturated FAs, PUFAs = polyunsaturated FAs. x denotes a significant difference of fish feed from sludge samples. Cage 1 Top Cage 1 Bottom Cage 2 Top Cage 2 Bottom Fish feed Total FAs (mg g − 1 DW) 56.04 ± 21.71 53.91 ± 14.26 80.11 ± 17.78 86.19 ± 33.88 225.64 ± 13.44 x % of total FAs C14:0 2.96 ± 0.29 2.86 ± 0.13 2.72 ± 0.15 2.71 ± 0.31 2.02 ± 0.02 C15:0 0.33 ± 0.05 0.32 ± 0.02 0.26 ± 0.02 0.27 ± 0.04 0.18 ± 0.00 C16:0 19.06 ± 3.39 18.37 ± 1.14 15.43 ± 1.28 15.70 ± 2.82 10.10 ± 0.03 C17:0 0.53 ± 0.05 0.50 ± 0.03 0.36 ± 0.14 0.31 ± 0.07 0.20 ± 0.00 C18:0 24.31 ± 2.66 20.88 ± 2.29 16.76 ± 0.34 16.17 ± 2.21 4.09 ± 0.02 C20:0 1.55 ± 0.24 1.45 ± 0.05 1.31 ± 0.05 1.37 ± 0.18 0.46 ± 0.00 C22:0 0.94 ± 0.41 0.95 ± 0.36 0.73 ± 0.16 0.84 ± 0.32 0.29 ± 0.00 ΣSAFAs 49.68 ± 6.67 45.33 ± 1.23 37.56 ± 1.47 37.36 ± 5.94 17.35 ± 0.02 x C14:1 n-5 0.05 ± 0.01 0.05 ± 0.01 0.06 ± 0.01 0.05 ± 0.01 0.06 ± 0.01 C16:1 n-9 0.14 ± 0.02 0.14 ± 0.01 0.12 ± 0.00 0.13 ± 0.01 0.11 ± 0.00 C16:1 n-7 1.87 ± 0.06 1.96 ± 0.16 2.20 ± 0.11 2.14 ± 0.14 2.46 ± 0.02 C16:1 n-5 0.22 ± 0.13 0.22 ± 0.13 0.17 ± 0.06 0.21 ± 0.14 0.15 ± 0.00 C18:1 n-9 24.61 ± 4.51 26.72 ± 1.45 32.37 ± 1.78 33.56 ± 4.57 38.03 ± 0.21 C18:1 n-7 2.38 ± 0.04 2.52 ± 0.14 2.94 ± 0.18 2.96 ± 0.18 2.41 ± 0.03 C20:1 n-9 3.22 ± 0.48 3.32 ± 0.34 4.26 ± 0.41 4.22 ± 0.43 2.98 ± 0.01 C22:1 n-11 0.52 ± 0.05 0.52 ± 0.08 0.63 ± 0.07 0.63 ± 0.01 0.31 ± 0.00 C22:1 n-9 3.09 ± 0.47 3.10 ± 0.36 3.78 ± 0.33 3.73 ± 0.26 2.58 ± 0.01 C24:1 0.88 ± 0.08 0.83 ± 0.18 0.77 ± 0.03 0.75 ± 0.06 0.29 ± 0.00 ΣMUFAs 36.97 ± 5.35 39.38 ± 1.89 47.3 ± 0.82 48.37 ± 5.22 49.39 ± 0.25 C16:2 0.05 ± 0.02 0.07 ± 0.02 0.10 ± 0.02 0.10 ± 0.03 0.18 ± 0.00 C18:2 n-6 7.65 ± 0.85 8.64 ± 1.41 8.73 ± 0.92 8.19 ± 0.60 15.59 ± 0.26 C18:3 n-3 1.87 ± 0.52 2.31 ± 0.44 2.64 ± 0.26 2.38 ± 0.29 8.32 ± 0.01 C18:4 n-3 0.27 ± 0.05 0.33 ± 0.07 0.29 ± 0.08 0.29 ± 0.06 0.83 ± 0.04 C20:2 n-6 0.23 ± 0.04 0.22 ± 0.03 0.24 ± 0.04 0.23 ± 0.01 0.11 ± 0.00 C20:4 n-6 ARA 0.25 ± 0.06 0.34 ± 0.09 0.12 ± 0.08 0.18 ± 0.03 0.28 ± 0.00 C20:3 n-3 0.06 ± 0.01 0.06 ± 0.01 0.06 ± 0.01 0.06 ± 0.00 0.05 ± 0.01 C20:5 n-3 EPA 0.57 ± 0.01 0.81 ± 0.33 0.66 ± 0.05 0.58 ± 0.11 3.52 ± 0.00 x C22:5 n-3 0.71 ± 0.14 0.72 ± 0.02 0.65 ± 0.01 0.75 ± 0.10 0.77 ± 0.02 C22:6 n-3 DHA 1.69 ± 0.04 1.79 ± 0.06 1.66 ± 0.22 1.48 ± 0.22 3.60 ± 0.04 x ΣPUFAs 13.35 ± 1.41 15.29 ± 2.07 15.15 ± 1.53 14.26 ± 1.08 33.26 ± 0.26 x Σn-3 5.17 ± 0.62 6.02 ± 0.83 5.95 ± 0.61 5.55 ± 0.55 17.09 ± 0.00 Σn-6 8.13 ± 0.82 9.20 ± 1.31 9.09 ± 0.91 8.61 ± 0.58 15.98 ± 0.26 DHA/EPA 5.91 ± 2.29 4.49 ± 0.98 3.21 ± 0.56 3.39 ± 1.51 0.45 ± 0.03 4 Discussion Our results show that varying feed input at different cages at the aquaculture site “Lamøya” lead to different quantities of sludge collected in the sediment traps, with a strong correlation between feed input and collected sludge and with no difference in the proportion of sludge that sedimented, when comparing the two different cages. Contrary to our hypothesis, we found no difference between sludge quantities collected at 39 m and 44 m water depth, suggesting a limited effect of ocean current on sludge sedimentation between these sampling points. This argumentation is supported by the site report of the studied site, in which average ocean current speeds of 8.0 cm s − 1 and 3.9 cm s − 1 were recorded at 5 m and 15 m depth, respectively (Havbrukstjenesten, 2013 ), showing a decrease in current speed with increasing depth. The quantification of sludge collected in this study confirms that, overall, only a small fraction of the sludge that is theoretically produced in salmon aquaculture sediments directly beneath the sea cages. The sedimented proportion that was calculated based on sludge collected by sediment traps was 10–15% of the total theoretically produced sludge, implying that most of the sludge is spread in proximity of farms, with the dispersal being influenced by environmental conditions and ocean currents (Law and Hill, 2019 , Carvajalino-Fernandez et al., 2020 ). Simulations by Broch et al. ( 2017 ) found that waste sludge from salmon cages sediments up to at least 500 m away from the farm and would hence not be registered in B-investigations which are carried out directly beneath the aquaculture site (Fiskeridirektoratet, 2023a ). Our findings of only low sedimentation directly beneath the sea cages, are supported by the latest B- and C-investigation that were conducted at the studied site. The B-investigation classified the general condition under the farm as 1 – very good, with no sludge being registered in any of the 13 grab samples and the benthic ecosystem being evaluated as healthy, with a turnover rate sufficient enough for the seafloor not to be negatively impacted by sludge dispersed from the salmon cages (Åkerblå, 2021 ). Results from the most recent C-investigation gave a “moderate” score with the highest organic matter load found southeast of the farm and the dispersal following the main current direction (Havbrukstjenesten, 2013 , Åkerblå, 2020 ). The quantity of sedimented sludge in this study may however have been affected by the presence of wild fish. Floating structures such as salmon farms have been described as fish aggregation devices (FADs), meaning wild fish aggregate around them to feed on uneaten feed (Dempster et al., 2009 , Sanchez-Jerez et al., 2011 ). Biomass estimates of wild fish underneath sea cages range from 10–100 tonnes which would have a significant impact on quantity of sludge that sediments to the sea floor as they a large proportion of feed pellets would be consumed before they can sediment sink down (Sæther et al., 2013 ). Finally, some uncertainties in our quantification results due to the used method cannot be excluded. When calculating the theoretical mass of produced sludge, a proportion of 13% feed spill was used, following Aas and Åsgård ( 2017 ). However, other studies have reported considerably lower numbers of 3–5% (Reid, 2007 , Wang et al., 2012 , Wang et al., 2013 ), suggesting a potential overestimation in the calculation of theoretically produced sludge in our study. Moreover, numbers of digestibility and defecation ratios vary. Wang and Olsen ( 2023 ) reported a defecation ratio of 18% as opposed to 30% which were used in this study based on numbers from Aas and Åsgård ( 2017 ). Additionally, the trap area was small compared to the total cage area which implicates that only small deviations in the mass of collected sludge would have a large effect on the calculated mass of sedimented sludge. When comparing the composition of sludge from sea-based salmon cages with that of land-based production, some differences were found. The ash content of sludge samples collected under the salmon farm was similar to that of sludge from land-based smolt production reported by Wang et al. ( 2019a ), while Anglade et al. ( 2023b ) reported a lower ash content for post-smolt sludge from brackish water production and a substantially lower ash content of smolt sludge collected from freshwater. Samples from a saline environment often exhibit a higher ash content due to a higher concentration of dissolved minerals and salts compared to freshwater. Since our study was conducted at open sea, the ash content of our samples could have further been elevated by shell, silt, and sand particles < 200 µm which were not removed during sample filtration (Nagao et al., 2001 ). Values of C and P content of sludge samples were substantially lower than those reported by Anglade et al. ( 2023a ), however when considering the differences in ash content and regarding the numbers as proportion of total organic matter (TOM), they fell within a comparable range. Further, the P content of sludge was similar to that of salmon feces (Wang et al., 2013 ). N, protein, and AA content was lower than that of sludge from land-based salmon production (Wang et al., 2019a , Anglade et al., 2023b , 2023a ) which can be explained by the changes in feed requirements for salmon and the correlated change in feces composition. In early life stages, salmon depend on a higher proportion of protein to support rapid growth and development (Nordgarden et al., 2002 ). As the fish age and go through transition to seawater environments, lipid requirements increase as lipid storage is crucial for maintaining buoyancy and thermal regulation (Sargent et al., 2002 ). Accordingly, the feed composition is adapted in farmed salmon (EWOS, 2022b , 2022a ) and therefore, sludge from earlier life stages may have a higher protein, AA, and N content but a lower lipid and FA content. Lipid content of sludge collected in our study was similar or higher to that reported in previous studies (Wang 2013, Wang 2019, Anglade 2019a), while the FA content was slightly lower. However, the lipid content of fish feed analyzed in this study was significantly lower than indicated by the producer (EWOS, 2022a ), suggesting that lipid and FA content of both fish feed and sludge may have been undervalued in our analyses. Lipid and protein content of sludge are moreover likely to have been affected by fish health. Prior to our study, salmon at the farm were diagnosed with pancreatic disease (PD) (BarentsWatch, 2022 ). Among other symptoms, PD caused by SAV2 leads to reduced appetite in salmon and can decrease both protein and lipid digestibility of feed (Røsæg et al., 2019 ), and, as a result, change the composition of feces and sludge. PCA revealed no effect of sampling location or depth on AA composition, however, a grouping of cages in the PCA plot was observed for FA composition. This may have either been influenced by the health status of the fish and the associated feed digestibility or a different proportion of feed spill in the cages. As described previously, a potentially large proportion of feed pellets from salmon farms may be consumed by wild fish that aggregate around the cages (Dempster et al., 2009 , Uglem et al., 2014 ). This does not only impact the quantity of sedimented sludge but also the composition. As reported by Wang et al. ( 2013 ), feed pellets have a higher nutritional value than salmon feces as they have a higher C, N, P, and lipid content. A smaller proportion of feed in sludge would explain the lower nutrient density of sludge collected in this trial compared to sludge from land-based aquaculture (Wang et al., 2019a , Anglade et al., 2023b , Anglade et al., 2023a ). Additionally, feed spill in land-based aquaculture has been reported to be higher compared to sea-based aquaculture (Aas and Åsgård, 2017 ) which would also lead to a higher proportion of feed to feces in sludge and hence a higher nutritional value of sludge from land-based aquaculture. Overall, there was no significant difference in ash, C, N, P, lipid, FA, protein, or AA content of sludge samples from different depths and different cages, suggesting that the composition of sludge that sedimented from salmon cages was independent of location at the farm or sampling depth within the scope of this study. However, more research is necessary to assess how seasonal variation (Wang and Olsen, 2023 ) and factors such as salmon size and health status affect quality of sludge that sediments from salmon cages. Although the majority of surveyed aquaculture sites scored highly in B- and C-investigations in the past (Fiskeridirektoratet, 2016, BarentsWatch, 2023 ), an increasing emphasis is placed on the environmental effects of high organic matter loading, especially with a continuously growing industry. Alongside other challenges such as diseases and escapees (Lekang et al., 2016 , Olaussen, 2018 ), a future scenario where salmon are cultivated in sea-based closed-containment systems becomes increasingly relevant. Closed-containment systems provide a more controlled environment, reducing the risk of disease transmission between farmed and wild fish. Further, they provide a physical barrier that reduces the risk of fish escapes and can help mitigate the environmental impact of salmon farming by preventing the direct release of nutrients, chemicals, and waste into surrounding waters as all intake and effluent water is filtrated (Rosten et al., 2011 , Nilsen, 2019 ). Though sludge from sea-based aquaculture may have a lower nutritional value than sludge from land-based production, cultivation in closed-containment systems would result in immense quantities of collected sludge that adequate applications are required for. Sludge from land-based aquaculture is currently used for biogas production, however, the salt content of saline sludge from sea-based production can change the bacterial community during biogas production and thus decrease biogas yield (Gebauer, 2004 , Mirzoyan et al., 2010 ). Additionally dewatering such large volumes of sludge would result in high energy consumption (Del Campo et al., 2010 , Aas and Åsgård, 2017 ) which makes it apparent that there is a need for alternative solutions. Following an IMTA approach, nutrient-rich waste sludge from salmon aquaculture can be utilized by lower trophic organisms such as polychaetes, as demonstrated by several studies (Nederlof et al., 2019 , Wang et al., 2019a , Anglade et al., 2023b ). Whether the composition of the sludge collected in this study could be suited for it to be used as a diet for polychaetes H. diversicolor depends upon different factors. In general, the nutrient composition and elemental ratios of organisms like H. diversicolor serve as a reliable indicator of their dietary nutrient needs (Sterner and Schulz, 1998 , Wagner et al., 2013 ). Due to a low N content of sludge collected in this study, the C:N ratio was substantially higher than that of sludge used for cultivation of polychaetes in other studies (Wang et al., 2019a , Anglade et al., 2023a ). Further, the N:P ratio of sludge was half that of sludge from land-based salmon production, which may affect efficient utilization of P. As N, AA and protein content were identified to promote polychaete growth (Santos et al., 2016 , Wang et al., 2019b ), a low content in sludge collected in our study, when comparing to previous trials, may pose a challenge and lead to reduced growth in H. diversicolor when fed with sludge from sea-based aquaculture as a sole feed source. In previous studies, the lipid content of H. diversicolor was strongly positively correlated with the lipid content of their diet. Since the lipid content of sludge collected in this study was similar or higher than that of sludge used by Wang et al. ( 2019a ) and Anglade et al. ( 2023b ), it can be considered appropriate for cultivation of the species. Although Anglade et al. ( 2023b ) reported no significant effect of a different ash content between smolt and post-smolt sludge on composition and growth on polychaetes, it should be considered whether the higher ash and associated salt content in sludge from sea-based aquaculture compared to sludge from land-based smolt and post-smolt production could affect digestibility in H. diversicolor . In summary, sludge from sea-based production collected in this study is probable to be an appropriate diet and the application should be investigated further in laboratory trials. An alternative to cultivation of H. diversicolor with sludge collected from sea-based salmon aquaculture would be a direct integration of naturally under salmon farm occurring polychaetes species such as Capitella sp. and Ophryotrocha craigsmithi , building on research by Kinoshita et al. ( 2008 ), Nederlof et al. ( 2019 ), and Nederlof et al. ( 2020 ). These species could be produced at high densities with a large biomass output (Tsutsumi et al., 2005 ) but, although initial efforts for a sea-based cultivation have been made, technical restraints persist and methods for cultivating and harvesting marine polychaetes beneath salmon farms have not been established (Jansen et al., 2019 , Nederlof et al., 2019 ). 5 Conclusion Our findings confirmed the hypothesis that the quantity of sedimented sludge will be different at different salmon cages at the same aquaculture site, with a strong positive correlation of feed input and sludge collection. The sedimented percentage of sludge as a proportion of theoretically produced sludge was similar for both cages and depths. Sampling depth did not affect the collected sludge quantity, suggesting a limited impact of ocean current underneath the sea cages at this specific location. With the exemption of FA composition, which seemed slightly affected by cage location, the composition of sedimented sludge was comparable across the salmon farm, with no significant difference of ash, C, N, P, lipid, FA, protein, or AA content between the different cages and sampling depths. The suitability of sludge collected in this study for cultivation of H. diversicolor using an IMTA approach was assessed theoretically, and although sludge collected from sea-based salmon production was found to have a lower nutritional value than that from land-based aquaculture, it could likely serve as a feed resource for production of polychaete biomass. Further confirmation in applied studies is, however, necessary. Declarations Funding We acknowledge funding by the RCN projects POLYCHAETE (#280836) and MIND-P (#268338) and would like to thank Måsøval AS for their assistance and enabling this study. Competing Interests The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Author Contributions IA: Conceptualization, Data curation, Formal analysis, Investigation, Visualization, Writing – original draft, Writing – review & editing. TMK: Formal analysis, Investigation, Writing – review. KIR: Conceptualization, Investigation, Project administration, Funding acquisition, Supervision, Writing – review & editing. Data Availability Statement The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation. References Anglade I, Kristensen BSB, Dahl TH, Hagemann A, Malzahn AM, Reitan KI (2023a) Upcycling of carbon, nitrogen, and phosphorus from aquaculture sludge using the polychaete Hediste diversicolor (OF Müller, 1776) (Annelida: Nereididae). 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Verlag Chemie Weinhein, New York, USA, pp 117–181 Law BA, Hill PS (2019) Spatial and temporal variation in cumulative mass eroded and organic matter percentage in surface sediments near areas of active salmon aquaculture. Aquac Environ Interact 11:305–320. https://doi.org/10.3354/aei00315 Lekang OI, Salas-Bringas C, Bostock JC (2016) Challenges and emerging technical solutions in on-growing salmon farming. Aquacult Int 24:757–766. https://doi.org/10.1007/s10499-016-9994-z Lovdata (2023) Forskrift om drift av akvakulturanlegg (akvakulturdriftsforskriften) § 35. Miljøovervåkning. https://lovdata.no/dokument/SF/forskrift/2008-06-17-822/KAPITTEL_3#%C2%A735 . Accessed 06.12.2023. Mirzoyan N, Tal Y, Gross A (2010) Anaerobic digestion of sludge from intensive recirculating aquaculture systems. 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Aquac Environ Interact 12:385–399. https://doi.org/10.3354/aei00371 Nilsen A (2019) Production of Atlantic salmon ( Salmo salar ) in closed confinement systems (CCS): salmon lice, growth rates, mortality and fish welfare. PhD Dissertation, Norwegian University of Life Sciences Nordgarden U, Hemre G-I, Hansen T (2002) Growth and body composition of Atlantic salmon ( Salmo salar L.) parr and smolt fed diets varying in protein and lipid contents. Aquaculture 207:65–78. https://doi.org/10.1016/S0044-8486(01)00750-5 Olafsen T, Winther U, Olsen Y, Skjermo J (2012) Value created from productive oceans in 2050. Report for The Royal Norwegian Society of Sciences and Letters (DKNVS) and Norwegian Academy of Technological Sciences (NTVA). DKNVS/NTVA, Trondheim, Norway Olaussen JO (2018) Environmental problems and regulation in the aquaculture industry. Insights Nor Mar Policy 98:158–163. https://doi.org/10.1016/j.marpol.2018.08.005 Olsen LM, Holmer M, Olsen Y (2008) Perspectives of nutrient emission from fish aquaculture in coastal waters. Literature review with evaluated state of knowledge. FHF project. https://doi.org/10.13140/RG.2.1.1273.8006 Olsen Y, Olsen L (2008) Environmental impact of aquaculture on coastal planktonic ecosystems. In: Tsukamoto K, Kawanuira T, Takeuchii T, Beard TD, Kaiser MJ (eds) Fisheries for global welfare and environment. 5th World Fisheries Congress 2008. TERRAPUB, Yokohama, Japan, pp 181–196 Reid GK (2007) Nutrient impacts of farmed Atlantic salmon ( Salmo salar ) on pelagic ecosystems and implications for carrying capacity. Chapter One: nutrient releases from salmon aquaculture. WWF Salmon Aquaculture Dialogue State of Information Reports Rosten TW, Ulgenes Y, Henriksen K, Terjesen BF, Biering E, Winther U (2011) Oppdrett av laks og ørret i lukkede anlegg-forprosjekt. Trondheim, Norway Røsæg MV, Rimstad E, Guttvik A, Skjelstad B, Bendiksen EÅ, Garseth ÅH (2019) Effect of pancreas disease caused by SAV 2 on protein and fat digestion in Atlantic salmon. J Fish Dis 42:97–108. https://doi.org/10.1111/jfd.12914 Sanchez-Jerez P, Fernandez-Jover D, Uglem I, Arechavala-López P, Dempster T, Bayle-Sempere JT, Valle Pérez C, Izquierdo D, Bjørn P-A, Nilsen R (2011) Coastal fish farms as fish aggregation devices (FADs). Artificial Reefs in Fishery Management. CRC Press. Taylor & Francis Group,, Florida, USA, pp 187–208 Santos A, Granada L, Baptista T, Anjos C, Simões T, Tecelão C, Fidalgo e, Costa P, Costa JL, Pombo A (2016) Effect of three diets on the growth and fatty acid profile of the common ragworm Hediste diversicolor (O. Aquaculture 1776:465, 37–42. https://doi.org/10.1016/j.aquaculture.2016.08.022 . .F. Müller Sargent J, Tocher D, Bell J (2002) The Lipids. In: Halver J, Hardy R (eds) Fish Nutrition. Academic, California, USA Shahbandeh M (2020) Distribution of salmon production worldwide in 2018, by leading country. https://www.statista.com/statistics/1182142/leading-salmon-producers-worldwide/ . Accessed 09.12.2023 Šližytė R, Opheim M, Storrø I, Sterten H (2017) Simple technologies for converting rest raw materials of Atlantic Salmon ( Salmo salar ) into high-quality, valuable, and tasty feed ingredients. J Aquat Food Prod Technol 26:604–619. https://doi.org/10.1080/10498850.2016.1247124 Standard N (2016) NS 9410:2016 Miljøovervåking av bunnpåvirkning fra marine akvakulturanlegg. https://online.standard.no/ns-9410-2016 . Accessed 05.12.2023. Sterner RW, Schulz KL (1998) Zooplankton nutrition: recent progress and a reality check. Aquat Ecol 32:261–279. https://doi.org/10.1023/a:1009949400573 Sæther B-S, Uglem I, Karlsen Ø (2013) Interaksjoner mellom havbruk og ville marine organismer - En kunnskapsoppsummering. Vedlegg til prosjektrapport ProCoEx prosjektnr 900772 Tomassetti P, Porrello S (2005) Polychaetes as indicators of marine fish farm organic enrichment. Aquacult Int 13:109–128. https://doi.org/10.1007/s10499-004-9026-2 Troell M, Joyce A, Chopin T, Neori A, Buschmann AH, Fang J-G (2009) Ecological engineering in aquaculture - Potential for integrated multi-trophic aquaculture (IMTA) in marine offshore systems. Aquaculture 297:1–9. https://doi.org/10.1016/j.aquaculture.2009.09.010 Tsutsumi H, Kinoshita K, Srithongouthai S, Sato A, Nagata S, Inoue A, Yoshioka M, Ohwada K, Hama D (2005) Treatment of the Organically Enriched Sediment below the Fish Farm with the Biological Activities of Artificially Mass-Cultured Colonies of a Small Deposit Feeding Polychaete, Capitella sp. I Benthos Res 60:25–38. https://doi.org/10.5179/benthos1996.60.1_25 Uglem I, Karlsen Ø, Sanchez-Jerez P, Sæther B (2014) Impacts of wild fishes attracted to open-cage salmonid farms in Norway. Aquac Environ Interact 6:91–103. https://doi.org/10.3354/aei00112 Valdemarsen T, Hansen PK, Ervik A, Bannister RJ (2015) Impact of deep-water fish farms on benthic macrofauna communities under different hydrodynamic conditions. Mar Pollut Bull 101:776–783. https://doi.org/10.1016/j.marpolbul.2015.09.036 Wagner ND, Hillebrand H, Wacker A, Frost PC (2013) Nutritional indicators and their uses in ecology. Ecol Lett 16:535–544. https://doi.org/10.1111/ele.12067 Wang C, Olsen Y (2023) Quantifying regional feed utilization, production and nutrient waste emission of Norwegian salmon cage aquaculture. Aquac Environ Interact 15:231–249. https://doi.org/10.3354/aei00463 Wang H, Seekamp I, Malzahn AM, Hagemann A, Carvajal AK, Slizyte R, Standal IB, Handå A, Reitan KI (2019a) Growth and nutritional composition of the polychaete Hediste diversicolor (OF Müller, 1776) cultivated on waste from land-based salmon smolt aquaculture. Aquaculture 502:232–241. https://doi.org/10.1016/j.aquaculture.2018.12.047 Wang H, Hagemann A, Reitan K, Ejlertsson J, Wollan H, Handå A, Malzahn AM (2019b) Potential of the polychaete Hediste diversicolor fed on aquaculture and biogas side streams as an aquaculture food source. Aquac Environ Interact 11:551–562. https://doi.org/10.3354/aei00331 Wang X, Olsen LM, Reitan KI, Olsen Y (2012) Discharge of nutrient wastes from salmon farms: environmental effects, and potential for integrated multi-trophic aquaculture. Aquac Environ Interact 2:267–283. https://doi.org/10.3354/aei00044 Wang X, Andresen K, Handå A, Jensen B, Reitan KI, Olsen Y (2013) Chemical composition and release rate of waste discharge from an Atlantic salmon farm with an evaluation of IMTA feasibility. Aquac Environ Interact 4:147–162. https://doi.org/10.3354/aei00079 Åkerblå (2020) C-undersøkelse NS9410:2016 for Lamøya. Frøya, Norway Åkerblå (2021) B-undersøkelse for lokalitet Lamøya NS9410:2016. Frøya, Norway Aas TS, Åsgård TE (2017) Estimated content of nutrients and energy in feed spill and faeces in Norwegian salmon culture. Nofima rapportserie 19 (2017), 1–8 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 18 Mar, 2024 Reviews received at journal 02 Mar, 2024 Reviewers agreed at journal 29 Feb, 2024 Reviewers invited by journal 21 Feb, 2024 Editor assigned by journal 21 Feb, 2024 Submission checks completed at journal 19 Feb, 2024 First submitted to journal 19 Feb, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-3969754","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":273795321,"identity":"16161c53-4a1e-4597-9f70-bc257067d201","order_by":0,"name":"Inka Anglade","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA2ElEQVRIiWNgGAWjYBACNiAEAwkQ8YFkLYwzGAyI0wTXwsxDjBY+6bbEDwx/bOQk20+nPbbd8SfP4ADvwQd47ZA5dliCsS3NWJond7tx7hmDYoMDfMl47WKTSG+QYGw4nDiPIXebdG6bQeKGAzxmEgS0NP9g+PO/fh7/223SlsRpSTsmwcB2IEFaAmgLI5Fa0iwS25INZ854u92wt804ceZhHmO8fpGfkWZ848MfO3mJ87nbHvxsk0vsO95j+ACfFjBIgNoIoZgJqkdyJAlqR8EoGAWjYCQBAEJLQ8kNEMWxAAAAAElFTkSuQmCC","orcid":"","institution":"Norwegian University of Science and Technology","correspondingAuthor":true,"prefix":"","firstName":"Inka","middleName":"","lastName":"Anglade","suffix":""},{"id":273795322,"identity":"709efa66-94b5-4ee9-b8e9-23b5810af84d","order_by":1,"name":"Trygve M. Krogli","email":"","orcid":"","institution":"Norwegian University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Trygve","middleName":"M.","lastName":"Krogli","suffix":""},{"id":273795323,"identity":"3f754df7-9331-4a2a-9d0d-0044c845a91b","order_by":2,"name":"Kjell Inge Reitan","email":"","orcid":"","institution":"Norwegian University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Kjell","middleName":"Inge","lastName":"Reitan","suffix":""}],"badges":[],"createdAt":"2024-02-19 10:46:11","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3969754/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3969754/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":51425461,"identity":"48aaf009-dc5f-4966-84a8-4398da4fbeda","added_by":"auto","created_at":"2024-02-21 11:24:43","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":241634,"visible":true,"origin":"","legend":"\u003cp\u003eLinear regression analysis of salmon feed input (kg DW d\u003csup\u003e-1\u003c/sup\u003e) and total sludge collected from sediment traps (mg DW d\u003csup\u003e-1\u003c/sup\u003e, sum of top and bottom trap) below Atlantic salmon sea cages. (C1 – Cage 1, C2 – Cage 2).\u003c/p\u003e","description":"","filename":"Figure1Anglade.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3969754/v1/fd193f9974b88760791a5253.jpg"},{"id":51425463,"identity":"5a46352b-4485-4586-b5f7-3e5ca358a245","added_by":"auto","created_at":"2024-02-21 11:24:44","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":286452,"visible":true,"origin":"","legend":"\u003cp\u003ePrincipal component analysis of amino acid composition (% of total amino acids) of sludge collected from sediment traps below Atlantic salmon sea cages, Cage 1 – Top, Cage 1 – Bottom, Cage 2 – Top, and Cage 2 – Bottom (n=3) and fish feed (n=3).\u003c/p\u003e","description":"","filename":"Figure2Anglade.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3969754/v1/b2179fe7009ef15290990432.jpg"},{"id":51425462,"identity":"26961e30-75d0-4b16-984e-ad60cccb02d8","added_by":"auto","created_at":"2024-02-21 11:24:43","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":359979,"visible":true,"origin":"","legend":"\u003cp\u003ePrincipal component analysis of fatty acid composition (% of total fatty acids) of sludge collected from sediment traps below Atlantic salmon sea cages, Cage 1 – Top, Cage 1 – Bottom, Cage 2 – Top, and Cage 2 – Bottom (n=3) and fish feed (n=2).\u003c/p\u003e","description":"","filename":"Figure3Anglade.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3969754/v1/6b482bd80e482e2053431902.jpg"},{"id":51426047,"identity":"1354ade3-0477-4090-8465-7d32f2a889a7","added_by":"auto","created_at":"2024-02-21 11:32:48","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":577887,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3969754/v1/a6eee9e3-e357-460f-8b4c-58a5a04e5b1d.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Sludge from sea-based Atlantic salmon (Salmo salar L.) production: quantification, composition, and potential application in IMTA","fulltext":[{"header":"1 Introduction","content":"\u003cp\u003eGlobal aquaculture production is increasingly gaining significance, given that the production has doubled in the last 20 years and quadrupled in the last 30 years (FAO, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Norway is the world's largest producer of Atlantic salmon (\u003cem\u003eSalmo salar\u003c/em\u003e L.), with a total production volume of 1.52\u0026nbsp;million tonnes in 2023 (Shahbandeh, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2020\u003c/span\u003e, Fiskeridirektoratet, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2024a\u003c/span\u003e). A production of this magnitude entails ecological challenges connected to salmon lice, escapees, and nutrient emissions from sea cages (Lekang et al., \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2016\u003c/span\u003e, Olaussen, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). These nutrient emissions are directly linked to the use of feed as up to 62% of carbon (C), 57% of nitrogen (N), and 76% of phosphorus (P) contained in the salmon feed are not utilized by the fish and thus released into the environment in the form of feed loss, feces production, excretion, and respiration (Wang et al., \u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e2012\u003c/span\u003e, Wang et al., \u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). Based on a feed consumption of 1.94\u0026nbsp;million tonnes reported in 2023 (Fiskeridirektoratet, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2024b\u003c/span\u003e), and an approximate content of 49% C, 6% N, and 1.5% P in feed (Olsen et al., \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2008\u003c/span\u003e), the calculated nutrient release from Norwegian salmon production in 2023 amounted to 588,000 tonnes C, 66,000 tonnes N, and 22,000 tonnes P. With a projected fourfold production by 2050, these numbers will correspondingly increase in the years to come (Olafsen et al., \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2012\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eWaste generated by salmon farms can be categorized into three groups: particulate organic matter (POM), dissolved organic matter (DOM), and dissolved inorganic matter (DIM) (S\u0026aelig;ther et al., \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). POM consists of particulate organic carbon (POC), particulate organic nitrogen (PON), and particulate organic phosphorus (POP) that originate from feed waste and feces and can serve as a nutrient source for organisms in water masses and benthic environments (Troell et al., \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). DOM are small molecules and particles that are resuspended from uneaten feed and feces; it is made up of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and dissolved organic phosphorus (DOP) (Fredriksen et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). DOM represents a minor fraction of the overall waste but is made up of stable substances with a prolonged turnover time that enters the microbial food web (S\u0026aelig;ther et al., \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). DIM consists of nutrients released into the water by fish through excretion and respiration. These nutrients are utilized by phytoplankton in the euphotic zone and macroalgae in the littoral zone (Olsen and Olsen, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2008\u003c/span\u003e, Husa et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2014\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eWhile the ecological effects of DOM and DIM are difficult to quantify, a monitoring program, following the Norwegian standard 9410, has been developed to quantify the effects of POM originating from salmon aquaculture on benthic habitats (Standard Norge, 2016, Lovdata, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). This standard consists of different types of analyses which include the B- and C-investigation. The B-investigation is a mandated trend monitoring for marine fish farming facilities in Norway which is carried out on site at regular intervals. It assesses seabed conditions beneath aquaculture facilities, utilizing a handheld grab for a qualitative evaluation based on three main categories: the presence of fauna, chemical condition, and sensory condition. The frequency of the B-investigation varies based on prior trend monitoring results, with poor conditions prompting more frequent assessments (Fiskeridirektoratet, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2023a\u003c/span\u003e). In 2021, 91% of the B-investigations performed at aquaculture sites scored either \u0026ldquo;good\u0026rdquo; or \u0026ldquo;very good\u0026rdquo; (BarentsWatch, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). The C-investigation is a comprehensive soft-bottom survey designed to evaluate the impact of aquaculture facilities on the adjacent seafloor. It extends outwards from the aquaculture site and surrounding waters, measuring sediment chemistry, composition, and benthic fauna. The investigation aims to identify the origin of organic material, determining whether it comes from the aquaculture facility or other sources in the vicinity (Fiskeridirektoratet, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2023b\u003c/span\u003e). In 2015\u0026ndash;2016, ca. 90% of surveyed aquaculture sites scored either \u0026ldquo;good\u0026rdquo; or \u0026ldquo;high\u0026rdquo; in the C-investigation (Fiskeridirektoratet, 2016). Results from C-investigations and literature show that different polychaete species are often found in high abundance beneath sea cages as they thrive in the organically enriched marine environments created by uneaten feed, fish feces, and other organic matter that accumulates in the sediment (Tomassetti and Porrello, \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2005\u003c/span\u003e, Bannister et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2014\u003c/span\u003e, Valdemarsen et al., \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). Using an integrated multi-trophic aquaculture (IMTA) approach, previous studies have given promising results for the application of polychaetes for recycling in waste sludge from salmon aquaculture, both from sea cages (Nederlof et al., \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2019\u003c/span\u003e, Nederlof et al., \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) and land-based production (Wang et al., \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2019a\u003c/span\u003e, Anglade et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2023b\u003c/span\u003e). Hereby, the species \u003cem\u003eHediste diversicolor\u003c/em\u003e has been focused on in several publications since it has not only been demonstrated to efficiently utilize nutrients contained in waste sludge but could also serve as a potential feed resource to be used in aquafeeds (Fidalgo e Costa et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2000\u003c/span\u003e, Bischoff et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2009\u003c/span\u003e, Wang et al., \u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e2019b\u003c/span\u003e, Wang et al., \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2019a\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe presented study aimed to quantify sedimentation of waste sludge directly under sea cages and assess the composition of this sludge. The potential use of this sludge from sea-based salmon aquaculture was evaluated as a feed source for polychaetes in an IMTA context. Hereby, the hypotheses were that 1) different salmon cages at the same aquaculture site will have a different quantity of sedimented sludge, depending on feed input, 2) the sludge quantity that sediments to the seafloor will be lower than directly beneath the cages, 3) the composition of sludge will not be affected by cage location at the farm or sampling depth, and 4) sludge that sediments from sea-based salmon aquaculture can be used as a resource for cultivation of polychaetes \u003cem\u003eH. diversicolor\u003c/em\u003e.\u003c/p\u003e"},{"header":"2 Material and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Collection of sludge\u003c/h2\u003e \u003cp\u003eSediment traps were used for the collection of sludge from salmon cages and at a reference site in August 2022. Sludge collection was conducted at two salmon sea cages (hereafter referred to as \u0026ldquo;Cage 1\u0026rdquo; and \u0026ldquo;Cage 2\u0026rdquo;, respectively) at the aquaculture site \"Lam\u0026oslash;ya\" (site no. 12993, M\u0026aring;s\u0026oslash;val AS), situated outside Sistranda in Tr\u0026oslash;ndelag county, Norway (63\u0026deg;43'59.0\"N, 8\u0026deg;51'17.9\"E). Sludge from the aquaculture site was collected at three samplings points (n\u0026thinsp;=\u0026thinsp;3), for 48 h at each sampling. As a reference site, a location approximately 3.5 km away and beyond the influence of any aquaculture sites was chosen (63\u0026deg;45'6.3\"N and 8\u0026deg;55'15.9\"E). Sample collection at the reference site ran for 7 days to accumulate sufficient material for analyses. The water depth at all sampling sites was approximately 50 m. The total cage depth of the salmon cages was 39 m. According to data obtained from M\u0026aring;s\u0026oslash;val AS, at the time of sludge sampling, Cage 1 held 105 372\u0026thinsp;\u0026plusmn;\u0026thinsp;300 fish with an average weight of 896\u0026thinsp;\u0026plusmn;\u0026thinsp;28 g, giving a total biomass of 94.42\u0026thinsp;\u0026plusmn;\u0026thinsp;2.67 tonnes, whereas Cage 2 held 75 012\u0026thinsp;\u0026plusmn;\u0026thinsp;331 fish with an average weight of 853\u0026thinsp;\u0026plusmn;\u0026thinsp;40 g, giving a total biomass of 63.99\u0026thinsp;\u0026plusmn;\u0026thinsp;2.76 tonnes. The feed used during the sampling period was RAPID HP 500 50A (7 mm, EWOS AS); salmon in Cage 1 were fed 642\u0026thinsp;\u0026plusmn;\u0026thinsp;206 kg d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e(DW), those in Cage 2 received 647\u0026thinsp;\u0026plusmn;\u0026thinsp;144 kg d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (DW) in the two days prior to the samplings.\u003c/p\u003e \u003cp\u003eThe sediment traps consisted of 4 PVC tubes, with a removable cup at the bottom of each tube. At each salmon cage, six traps were attached to the floating collar of the cage; three traps were placed right beneath the cage at 39 m depth (\u0026ldquo;Top (T)\u0026rdquo;) and three traps were placed close to the seafloor at 44 m depth (\u0026ldquo;Bottom (B)\u0026rdquo;). At the reference site, three sets of traps that were attached to buoys were deployed at the same depths as those at the salmon cages (39 m and 44 m). After the sampling period, the sediment traps were retrieved and transported to the feed barge. There, the traps were left for 5 min to allow for the sample material to settle on the bottom of the trap. Excess seawater was removed from the PVC tubes using a pump that was equipped with a 300 \u0026micro;m filter on the inlet and a 200 \u0026micro;m filter on the outlet to avoid any accidental pumping of sample material. Approximately 100 mL seawater containing the sampling material were left in the sampling tube. The cups holding the rest of the seawater and the sample were then detached from the sediment trap. The content of four tubes that make up one sediment trap was transferred into sampling bottles and frozen at -20\u0026deg;C. In preparation for further analyses, samples were centrifuged for a total of 15 min at 5000 rpm, using a Sorwall RC-5C Plus centrifuge for 5 min, and a Heraeus Labofuge 400R (both Thermo Fisher Scientific, USA) for an additional 2 x 5 min. Subsequently, samples were freeze-dried, and the dry weight was recorded (balance: XA204DR, Mettler Toledo, Switzerland).\u003c/p\u003e \u003cp\u003eFrom each salmon cage, the samples from the three sediment traps at the same depth were pooled after drying, which gives the four different sampling groups: Cage 1 \u0026ndash; Top (\u0026ldquo;C1T\u0026rdquo;), Cage 1 \u0026ndash; Bottom (\u0026ldquo;C1B\u0026rdquo;), Cage 2 \u0026ndash; Top (\u0026ldquo;C2T\u0026rdquo;), and Cage 2 \u0026ndash; Bottom (\u0026ldquo;C2B\u0026rdquo;). From the reference site, samples from the three top traps and the three bottom traps, respectively, were pooled for quantification of sample material. For chemical analyses, all samples from the reference site were pooled.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Chemical analyses\u003c/h2\u003e \u003cp\u003eSamples from the sediment traps at the salmon farm and the reference site were analyzed for their C, N, and P content, elemental ratios, and ash content. Samples from the salmon farm were further analyzed for total lipid content, fatty acid (FA) content and composition, amino acid (AA) content and composition, and protein content. Ash content was measured by combustion of samples in a muffle furnace at 450\u0026deg;C for 5 hours. C and N were examined via gas chromatography in an organic elemental analyzer (Vario EL Cube, Elementar Analysensysteme GmbH, Germany) with acetonitrile as the reference standard. P was oxidized using potassium peroxydisulfate, as outlined in the methodology by Koroleff (\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e1976\u003c/span\u003e). Subsequently, quantitative analysis of phosphate content was conducted photometrically using an autoanalyzer (Flow Solution IV, O.I Analytical) following NS-EN ISO 6878. The elemental ratios of C:N, C:P, and N:P were calculated based on the respective C, N, and P content (mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e DW).\u003c/p\u003e \u003cp\u003eLipids were extracted with chloroform (CHCl\u003csub\u003e3\u003c/sub\u003e) and methanol (CH\u003csub\u003e3\u003c/sub\u003eOH) (2:1 v/v) following Folch et al. (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e1957\u003c/span\u003e) and subsequently gravimetrically quantified. Following lipid extraction, FAs were hydrolyzed and esterified to fatty acid methyl esters with methanol, and then analyzed by means of gas chromatography (7890B GC, Agilent Technologies, USA) equipped with helium carrier gas, a WCOT fused-silica capillary column coated with CP-wax 52CB (Holger CP7713) and a flame ionization detector (FID). AAs were analyzed according to Šližytė et al. (\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). Samples were hydrolyzed at 110\u0026deg;C in 6 M HCL containing 0.4% mercaptoethanol for 24 h, followed by filtration using Whatman glass microfiber filters (grade GF/C, 47 mm). The pH was subsequently adjusted to 2.2 and the samples were then separated through a high-performance liquid chromatography (HPLC) system (Agilent Infinity 1260, Agilent Technologies, USA), which was coupled to an online post-column derivatization module (Pinnacle PCX, Pickering Laboratories, USA). Protein content was calculated by summation of water-free AAs.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Quantification of sludge collection and dispersal\u003c/h2\u003e \u003cp\u003eThe collected sample material at the two different depths at each of the salmon cages and the reference site were quantified, and the amount of sludge that sedimented at each depth at the aquaculture site was calculated by extrapolation of the trap area to the total cage area.\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$${m}_{sedimented sludge}=\\frac{{A}_{cage}}{{A}_{traps}}*{m}_{collected sludge}$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eWhere m\u003csub\u003esedimented sludge\u003c/sub\u003e (kg DW d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) is the calculated mass of sedimented sludge for the whole cage, A\u003csub\u003ecage\u003c/sub\u003e (m\u003csup\u003e2\u003c/sup\u003e) is the cage area, A\u003csub\u003etraps\u003c/sub\u003e (m\u003csup\u003e2\u003c/sup\u003e) is the combined area of all three sediment traps at each depth, and m\u003csub\u003ecollected sludge\u003c/sub\u003e (kg DW d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) is the mass of collected sludge that was recorded in our experiment. The four PVC tubes that made up one sediment trap had an inner diameter of 6.50 cm each, giving a total area of 132.73*10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e m\u003csup\u003e2\u003c/sup\u003e per trap. The total collection area A\u003csub\u003etraps\u003c/sub\u003e, consisting of three traps at each depth, was 398.20*10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e m\u003csup\u003e2\u003c/sup\u003e. The total salmon cage area is defined by the circumference of the cages of 120 m, giving a cage area A\u003csub\u003ecage\u003c/sub\u003e of 1145.92 m\u003csup\u003e2\u003c/sup\u003e. The mass of collected sludge m\u003csub\u003ecollected sludge\u003c/sub\u003e was calculated by deducting the mass of sample material (kg DW d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) collected at the reference site from the mass of sludge (kg DW d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) collected under the salmon cages for each sediment trap to adjust for naturally occurring POM.\u003c/p\u003e \u003cp\u003eThe theoretical production of sludge (kg DW d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) was quantified based on Aas and \u0026Aring;sg\u0026aring;rd (\u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e2017\u003c/span\u003e), where the assumption is made that 87% of supplied salmon feed (DW) is ingested, meaning 13% remain uneaten. The ingested feed has an apparent digestibility of 70%, while 30% of ingested feed will be defecated. Based on these numbers, the total theoretical sludge production, which is made up of uneaten feed and feces, will be 39.1% of supplied feed (kg DW d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e). The sedimented proportion was calculated by dividing the mass of theoretically produced sludge (kg DW d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) by the mass of sedimented sludge (kg DW d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Statistical analysis\u003c/h2\u003e \u003cp\u003eStatistical analyses were carried out using Sigmaplot for Windows Version 14.0 (Systat Software, Inc., USA). Minitab\u0026reg; 21.1 (Minitab, LLC) was used for principal component analysis (PCA) of FA and AA composition of sludge samples collected at the salmon farm.\u003c/p\u003e \u003cp\u003eNormal distribution of data was assessed using Shapiro-Wilk tests, and homogeneity of variance was examined using Brown-Forsythe tests. For the comparison of two groups, Welch's t-test was employed. In cases where the data did not follow a normal distribution, log transformation was applied or a non-parametric test, the Mann-Whitney Rank Sum Test for two-group comparisons, was used. Results from sludge sample qualification, namely, ash, lipid, FA, protein, AA, C, N, and P content, as well as elemental ratios, percentages of saturated FAs (SAFAs), monounsaturated FAs (MUFAs), polyunsaturated FAs (PUFAs) and percentages of essential AAs (EAA) and non-essential AAs (NEAAs) were compared at the two different depths at the same cage (C1T vs. C1B and C2T vs. C2B) and the same depth at the two different cages (C1T vs. C2T and C1B vs. C2B). Additionally, C, N, and P content of samples at the reference site was compared with those from the salmon cages. Results from qualification of fish feed were compared with sludge samples using one-way analysis of variance (ANOVA) followed by pairwise multiple comparisons using the Holm-Sidak method. As for sample quantification, C1T vs. C2T and C1B vs. C2B were analyzed for significant differences in the percentage of sludge that was collected. Further, linear regression analysis was conducted to display the relationship between salmon feed supplied and sludge collected under the salmon cages.\u003c/p\u003e \u003cp\u003eAll statistical analyses were carried out at the 95% confidence level (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e \u003c/div\u003e"},{"header":"3 Results","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Quantification of sedimented sludge\u003c/h2\u003e \u003cp\u003eFeed input and the correlated theoretical production of sludge at the two different salmon cages varied between sampling dates (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). A similar mass of sludge (kg DW d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) was collected right under the salmon cages (Top) and on the seafloor (Bottom) on all sampling dates at both cages. There was no significant difference in the sedimented proportion (%) when comparing different depths at the same cages and the same depths at different cages (C1T vs. C1B and C2T vs. C2B) (Welch\u0026rsquo;s t-test, p\u0026thinsp;\u0026ge;\u0026thinsp;0.05). Linear regression analysis found a strong positive correlation (R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.98, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) between the feed supplied to the salmon and the sludge that was collected by the sediment traps (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eFeed input (kg DW d\u003csup\u003e-1\u003c/sup\u003e), theoretically produced sludge (kg DW d\u003csup\u003e-1\u003c/sup\u003e), sedimented sludge (kg DW d\u003csup\u003e-1\u003c/sup\u003e), and sedimented proportion of sludge (%) from sediment traps below Atlantic salmon sea cages, right under the cages (Top) and on the seafloor (Bottom).\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCage no.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDate\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFeed input\u003c/p\u003e \u003cp\u003e(kg DW d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTheoretically produced sludge (kg DW d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eTrap position\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eSedimented sludge\u003c/p\u003e \u003cp\u003e(kg DW d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eSedimented proportion (%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"5\" rowspan=\"6\"\u003e \u003cp\u003eCage 1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e11.08.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e433.60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e169.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eTop\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e29.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e17.13\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eBottom\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e23.35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e13.77\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e17.08.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e645.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e252.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eTop\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e39.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e15.49\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eBottom\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e38.99\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e15.45\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e24.08.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e846.37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e330.93\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eTop\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e36.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e10.95\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eBottom\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e33.55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e10.14\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"5\" rowspan=\"6\"\u003e \u003cp\u003eCage 2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e11.08.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e485.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e189.80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eTop\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e20.21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e10.65\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eBottom\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e22.38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e11.79\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e17.08.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e692.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e270.68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eTop\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e35.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e13.27\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eBottom\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e32.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e11.89\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e24.08.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e763.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e298.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eTop\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e37.75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e12.64\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eBottom\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e36.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e12.08\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Biochemical composition of reference site samples, sludge samples from the salmon farm, and fish feed\u003c/h2\u003e \u003cp\u003eC content (mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e DW) of samples collected under the salmon cages was similar at the same depth at different cages (C1T vs. C2T and C1B vs C2B) and different depths at the same cage (Welch\u0026rsquo;s t-test, p\u0026thinsp;\u0026ge;\u0026thinsp;0.05, Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Further, all samples from the salmon cages had a significantly higher C content than samples collected at the reference site (one-way ANOVA, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). The C content of fish feed was significantly higher than that of the sludge samples (one-way ANOVA, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). N content (mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e DW) of sludge samples was similar at different depths and different cages (Welch\u0026rsquo;s t-test, p\u0026thinsp;\u0026ge;\u0026thinsp;0.05), and not different from the reference samples (one-way ANOVA, p\u0026thinsp;\u0026ge;\u0026thinsp;0.05). Fish feed had a significantly higher N content than sludge samples (one-way ANOVA, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). No difference in P content (mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e DW) of samples collected under the salmon cages was found between the different sampling groups (Welch\u0026rsquo;s t-test, p\u0026thinsp;\u0026ge;\u0026thinsp;0.05). However, sludge samples had a significantly higher P content than reference samples (one-way ANOVA, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05), with sludge samples containing 13\u0026ndash;18 times as much P as samples at the reference site. The P content of fish feed was not significantly different from that of sludge samples (one-way ANOVA, p\u0026thinsp;\u0026ge;\u0026thinsp;0.05). The C:N ratio of sludge samples was similar at different depths and different cages (Welch\u0026rsquo;s t-test, p\u0026thinsp;\u0026ge;\u0026thinsp;0.05), and significantly higher than that of samples collected at the reference site (one-way ANOVA, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). A significantly lower C:N ratio of fish feed compared to sludge samples was found (one-way ANOVA, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). There was no significant difference in C:P ratio of sludge samples when comparing sampling groups (Welch\u0026rsquo;s t-test, p\u0026thinsp;\u0026ge;\u0026thinsp;0.05), and all sludge samples had a significantly lower C:P ratio than reference samples (one-way ANOVA, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). The C:P ratio of fish feed was significantly higher than that of sludge samples (one-way ANOVA, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). The N:P ratio was similar for all sludge samples (Welch\u0026rsquo;s t-test, p\u0026thinsp;\u0026ge;\u0026thinsp;0.05), while the N:P ratio of reference samples was significantly higher (one-way ANOVA, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Fish feed had an N:P ratio that was significantly higher than that of sludge samples (one-way ANOVA, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eCarbon (C), nitrogen (N), and phosphorus (P) content (mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD, mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e DW), and C:N, C:P, and N:P ratios (-) of sludge collected from sediment traps below Atlantic salmon sea cages, Cage 1 \u0026ndash; Top, Cage 1 \u0026ndash; Bottom, Cage 2 \u0026ndash; Top, and Cage 2 \u0026ndash; Bottom (n\u0026thinsp;=\u0026thinsp;3), sediment traps from a reference site (n\u0026thinsp;=\u0026thinsp;3), and fish feed (n\u0026thinsp;=\u0026thinsp;3). Asterisks denote significant differences from the reference site and \u003csup\u003ex\u003c/sup\u003e denotes a significant difference of fish feed from sludge samples.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCage 1 \u0026ndash; Top\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCage 1 \u0026ndash; Bottom\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCage 2 \u0026ndash; Top\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCage 2 \u0026ndash; Bottom\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eReference site\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eFish feed\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCarbon (mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e DW)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e197.02\u0026thinsp;\u0026plusmn;\u0026thinsp;35.12\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e183.56\u0026thinsp;\u0026plusmn;\u0026thinsp;53.62\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e212.12\u0026thinsp;\u0026plusmn;\u0026thinsp;56.37\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e209.16\u0026thinsp;\u0026plusmn;\u0026thinsp;60.59\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e \u003cp\u003e115.17\u0026thinsp;\u0026plusmn;\u0026thinsp;7.83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e454.21\u0026thinsp;\u0026plusmn;\u0026thinsp;17.57\u003csup\u003ex\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNitrogen (mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e DW)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e8.63\u0026thinsp;\u0026plusmn;\u0026thinsp;1.73\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e8.22\u0026thinsp;\u0026plusmn;\u0026thinsp;2.58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e7.79\u0026thinsp;\u0026plusmn;\u0026thinsp;2.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e7.74\u0026thinsp;\u0026plusmn;\u0026thinsp;3.49\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e \u003cp\u003e9.51\u0026thinsp;\u0026plusmn;\u0026thinsp;1.19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e65.96\u0026thinsp;\u0026plusmn;\u0026thinsp;3.4\u003csup\u003ex\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePhosphorus (mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003eDW)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e20.44\u0026thinsp;\u0026plusmn;\u0026thinsp;5.5\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e16.89\u0026thinsp;\u0026plusmn;\u0026thinsp;7.1\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e23.47\u0026thinsp;\u0026plusmn;\u0026thinsp;9.32\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e18.35\u0026thinsp;\u0026plusmn;\u0026thinsp;7.48\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e \u003cp\u003e1.29\u0026thinsp;\u0026plusmn;\u0026thinsp;0.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e14.23\u0026thinsp;\u0026plusmn;\u0026thinsp;0.26\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC:N (-)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e23.06\u0026thinsp;\u0026plusmn;\u0026thinsp;2.98\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e22.91\u0026thinsp;\u0026plusmn;\u0026thinsp;5.06\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e27.82\u0026thinsp;\u0026plusmn;\u0026thinsp;6.3\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e30.39\u0026thinsp;\u0026plusmn;\u0026thinsp;10.28\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e \u003cp\u003e12.20\u0026thinsp;\u0026plusmn;\u0026thinsp;1.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e6.90\u0026thinsp;\u0026plusmn;\u0026thinsp;0.59\u003csup\u003ex\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC:P (-)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e10.03\u0026thinsp;\u0026plusmn;\u0026thinsp;1.92\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e11.42\u0026thinsp;\u0026plusmn;\u0026thinsp;1.83\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e10.28\u0026thinsp;\u0026plusmn;\u0026thinsp;4.81\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e11.98\u0026thinsp;\u0026plusmn;\u0026thinsp;2.87\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e \u003cp\u003e89.89\u0026thinsp;\u0026plusmn;\u0026thinsp;8.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e31.94\u0026thinsp;\u0026plusmn;\u0026thinsp;1.78\u003csup\u003ex\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eN:P (-)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.45\u0026thinsp;\u0026plusmn;\u0026thinsp;0.13\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.54\u0026thinsp;\u0026plusmn;\u0026thinsp;0.24\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e0.39\u0026thinsp;\u0026plusmn;\u0026thinsp;0.21\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e0.44\u0026thinsp;\u0026plusmn;\u0026thinsp;0.19\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e \u003cp\u003e7.46\u0026thinsp;\u0026plusmn;\u0026thinsp;1.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e4.63\u0026thinsp;\u0026plusmn;\u0026thinsp;0.16\u003csup\u003ex\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eAsh content (mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e DW) of sludge samples was similar across sampling groups and not significantly different from samples at the reference site (Welch\u0026rsquo;s t-test, p\u0026thinsp;\u0026ge;\u0026thinsp;0.05, Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). The ash content of fish feed was significantly lower than that of sludge samples (one-way ANOVA, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). No difference between sludge samples at different depths or different cages was found for the content of protein and lipid (mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e DW), while fish feed had a significantly higher protein and lipid content than sludge samples. The content of unidentified material (which includes carbohydrates) (mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e DW) was not significantly different between sludge samples (Welch\u0026rsquo;s t-test, p\u0026thinsp;\u0026ge;\u0026thinsp;0.05) and when comparing sludge samples with fish feed (one-way ANOVA, p\u0026thinsp;\u0026ge;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComposition (mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD) of sludge collected from sediment traps below Atlantic salmon sea cages, Cage 1 \u0026ndash; Top, Cage 1 \u0026ndash; Bottom, Cage 2 \u0026ndash; Top, and Cage 2 \u0026ndash; Bottom (n\u0026thinsp;=\u0026thinsp;3), sediment traps from a reference site (n\u0026thinsp;=\u0026thinsp;3, ND\u0026thinsp;=\u0026thinsp;no data), and fish feed (n\u0026thinsp;=\u0026thinsp;3). \u003csup\u003ex\u003c/sup\u003e denotes a significant difference of fish feed from sludge samples.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCage 1 \u0026ndash; Top\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCage 1 \u0026ndash; Bottom\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCage 2 \u0026ndash; Top\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCage 2 \u0026ndash; Bottom\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eReference site\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eFish feed\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAsh\u0026nbsp;(mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e DW)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e476.48\u0026thinsp;\u0026plusmn;\u0026thinsp;109.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e507.18\u0026thinsp;\u0026plusmn;\u0026thinsp;79.99\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e461.16\u0026thinsp;\u0026plusmn;\u0026thinsp;106.68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e472.04\u0026thinsp;\u0026plusmn;\u0026thinsp;133.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e658.93\u0026thinsp;\u0026plusmn;\u0026thinsp;13.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e82.74\u0026thinsp;\u0026plusmn;\u0026thinsp;0.952\u003csup\u003ex\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eProtein\u0026nbsp;(mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e DW)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e62.67\u0026thinsp;\u0026plusmn;\u0026thinsp;18.93\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e70.54\u0026thinsp;\u0026plusmn;\u0026thinsp;3.68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e71.42\u0026thinsp;\u0026plusmn;\u0026thinsp;17.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e67.42\u0026thinsp;\u0026plusmn;\u0026thinsp;20.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eND\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e366.39\u0026thinsp;\u0026plusmn;\u0026thinsp;19.37\u003csup\u003ex\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLipids\u0026nbsp;(mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e DW)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e97.05\u0026thinsp;\u0026plusmn;\u0026thinsp;30.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e92.82\u0026thinsp;\u0026plusmn;\u0026thinsp;22.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e125.54\u0026thinsp;\u0026plusmn;\u0026thinsp;27.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e127.93\u0026thinsp;\u0026plusmn;\u0026thinsp;45.83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eND\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e241.93\u0026thinsp;\u0026plusmn;\u0026thinsp;15.62\u003csup\u003ex\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUnidentified material\u0026nbsp;(mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e DW)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e363.8\u0026thinsp;\u0026plusmn;\u0026thinsp;62.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e329.47\u0026thinsp;\u0026plusmn;\u0026thinsp;61.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e341.88\u0026thinsp;\u0026plusmn;\u0026thinsp;62.59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e332.62\u0026thinsp;\u0026plusmn;\u0026thinsp;68.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eND\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e308.94\u0026thinsp;\u0026plusmn;\u0026thinsp;18.74\u003csup\u003ex\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAmino acids\u0026nbsp;(mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e DW)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e73.26\u0026thinsp;\u0026plusmn;\u0026thinsp;22.19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e82.52\u0026thinsp;\u0026plusmn;\u0026thinsp;4.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e83.74\u0026thinsp;\u0026plusmn;\u0026thinsp;20.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e79.02\u0026thinsp;\u0026plusmn;\u0026thinsp;23.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eND\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e426.16\u0026thinsp;\u0026plusmn;\u0026thinsp;22.44\u003csup\u003ex\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFatty acids\u0026nbsp;(mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e DW)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e56.04\u0026thinsp;\u0026plusmn;\u0026thinsp;21.71\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e53.91\u0026thinsp;\u0026plusmn;\u0026thinsp;14.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e80.11\u0026thinsp;\u0026plusmn;\u0026thinsp;17.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e86.19\u0026thinsp;\u0026plusmn;\u0026thinsp;33.88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eND\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e225.64\u0026thinsp;\u0026plusmn;\u0026thinsp;13.44\u003csup\u003ex\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe total AA content (mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e DW) of sludge samples was not significantly different at different depths or different cages (Welch\u0026rsquo;s t-test, p\u0026thinsp;\u0026ge;\u0026thinsp;0.05), fish feed, however, had a significantly higher AA content than all sludge samples (one-way ANVOA, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05, Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). The sludge samples at different depths or at different cages showed no significant differences for the relative content of ΣEAA (% of total AAs) (Welch\u0026rsquo;s t-test, p\u0026thinsp;\u0026ge;\u0026thinsp;0.05, Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Further, no difference was detected for ΣNEAA content (% of total AAs). A significantly lower proportion of EAA and a significantly higher percentage of NEAA was found when comparing fish feed with sludge samples (one-way ANVOA, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Leucine, phenylalanine, and lysine were the EAAs with the largest proportions in sludge samples. In fish feed, leucine, lysine, arginine, and phenylalanine were the most abundant EAAs. Of the NEAAs, glutamic acid\u0026thinsp;+\u0026thinsp;glutamine, alanine, serine, and aspartic acid\u0026thinsp;+\u0026thinsp;asparagine had the largest share of total AA, both in sludge samples and fish feed. PCA revealed that relative AA composition (% of total AAs) of sludge samples was not affected by the position at the farm (Cage 1 or 2) or the water depth at which they were taken (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Differences in variance of AA composition were smaller between the different sludge samples than when comparing sludge samples to fish feed. Together, PC1 and PC2 explained 67% of the variance in AA composition.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eRelative amino acid (AA) composition (% of total AAs) of sludge collected from sediment traps below Atlantic salmon sea cages, Cage 1 \u0026ndash; Top, Cage 1 \u0026ndash; Bottom, Cage 2 \u0026ndash; Top, and Cage 2 \u0026ndash; Bottom (n\u0026thinsp;=\u0026thinsp;3) and fish feed (n\u0026thinsp;=\u0026thinsp;2). EEAs\u0026thinsp;=\u0026thinsp;essential AAs, NEAA\u0026thinsp;=\u0026thinsp;non-essential AAs. \u003csup\u003ex\u003c/sup\u003e denotes a significant difference of fish feed from sludge samples.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCage 1\u003c/p\u003e \u003cp\u003eTop\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCage 1\u003c/p\u003e \u003cp\u003eBottom\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCage 2\u003c/p\u003e \u003cp\u003eTop\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCage 2\u003c/p\u003e \u003cp\u003eBottom\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eFish feed\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTotal AAs (mg g\u003c/b\u003e\u003csup\u003e\u003cb\u003e\u0026minus;\u0026thinsp;1\u003c/b\u003e\u003c/sup\u003e \u003cb\u003eDW)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e73.26\u0026thinsp;\u0026plusmn;\u0026thinsp;18.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e82.52\u0026thinsp;\u0026plusmn;\u0026thinsp;3.46\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e83.74\u0026thinsp;\u0026plusmn;\u0026thinsp;16.82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e79.02\u0026thinsp;\u0026plusmn;\u0026thinsp;19.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e426.16\u0026thinsp;\u0026plusmn;\u0026thinsp;22.44\u003csup\u003ex\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e% of total AAs\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eArginine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.19\u0026thinsp;\u0026plusmn;\u0026thinsp;0.61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.07\u0026thinsp;\u0026plusmn;\u0026thinsp;0.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.87\u0026thinsp;\u0026plusmn;\u0026thinsp;0.56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3.11\u0026thinsp;\u0026plusmn;\u0026thinsp;0.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e6.54\u0026thinsp;\u0026plusmn;\u0026thinsp;0.28\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHistidine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.36\u0026thinsp;\u0026plusmn;\u0026thinsp;0.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.35\u0026thinsp;\u0026plusmn;\u0026thinsp;0.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.74\u0026thinsp;\u0026plusmn;\u0026thinsp;0.52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.20\u0026thinsp;\u0026plusmn;\u0026thinsp;0.24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2.16\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIsoleucine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6.50\u0026thinsp;\u0026plusmn;\u0026thinsp;0.68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6.77\u0026thinsp;\u0026plusmn;\u0026thinsp;0.82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6.34\u0026thinsp;\u0026plusmn;\u0026thinsp;0.28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e6.18\u0026thinsp;\u0026plusmn;\u0026thinsp;0.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4.41\u0026thinsp;\u0026plusmn;\u0026thinsp;0.03\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLeucine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9.19\u0026thinsp;\u0026plusmn;\u0026thinsp;0.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9.02\u0026thinsp;\u0026plusmn;\u0026thinsp;0.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9.49\u0026thinsp;\u0026plusmn;\u0026thinsp;0.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8.83\u0026thinsp;\u0026plusmn;\u0026thinsp;0.52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e7.62\u0026thinsp;\u0026plusmn;\u0026thinsp;0.03\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLysine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4.60\u0026thinsp;\u0026plusmn;\u0026thinsp;0.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.61\u0026thinsp;\u0026plusmn;\u0026thinsp;0.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4.20\u0026thinsp;\u0026plusmn;\u0026thinsp;0.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4.54\u0026thinsp;\u0026plusmn;\u0026thinsp;0.15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e6.96\u0026thinsp;\u0026plusmn;\u0026thinsp;0.19\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMethionine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.52\u0026thinsp;\u0026plusmn;\u0026thinsp;0.31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.35\u0026thinsp;\u0026plusmn;\u0026thinsp;0.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.40\u0026thinsp;\u0026plusmn;\u0026thinsp;0.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.15\u0026thinsp;\u0026plusmn;\u0026thinsp;0.19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2.08\u0026thinsp;\u0026plusmn;\u0026thinsp;0.06\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePhenylalanine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8.00\u0026thinsp;\u0026plusmn;\u0026thinsp;0.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7.74\u0026thinsp;\u0026plusmn;\u0026thinsp;0.79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.76\u0026thinsp;\u0026plusmn;\u0026thinsp;0.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e7.41\u0026thinsp;\u0026plusmn;\u0026thinsp;0.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4.66\u0026thinsp;\u0026plusmn;\u0026thinsp;0.07\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eThreonine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4.55\u0026thinsp;\u0026plusmn;\u0026thinsp;0.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.63\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4.58\u0026thinsp;\u0026plusmn;\u0026thinsp;0.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4.50\u0026thinsp;\u0026plusmn;\u0026thinsp;0.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e3.16\u0026thinsp;\u0026plusmn;\u0026thinsp;0.07\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTryptophan\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eValine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6.64\u0026thinsp;\u0026plusmn;\u0026thinsp;0.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6.19\u0026thinsp;\u0026plusmn;\u0026thinsp;0.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6.50\u0026thinsp;\u0026plusmn;\u0026thinsp;0.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e6.26\u0026thinsp;\u0026plusmn;\u0026thinsp;0.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e5.09\u0026thinsp;\u0026plusmn;\u0026thinsp;0.09\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eΣEAAs\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e47.55\u0026thinsp;\u0026plusmn;\u0026thinsp;0.58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e46.73\u0026thinsp;\u0026plusmn;\u0026thinsp;1.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e47.88\u0026thinsp;\u0026plusmn;\u0026thinsp;0.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e45.18\u0026thinsp;\u0026plusmn;\u0026thinsp;0.70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e42.69\u0026thinsp;\u0026plusmn;\u0026thinsp;0.70\u003csup\u003ex\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAlanine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7.29\u0026thinsp;\u0026plusmn;\u0026thinsp;0.31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7.37\u0026thinsp;\u0026plusmn;\u0026thinsp;0.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.53\u0026thinsp;\u0026plusmn;\u0026thinsp;0.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e7.95\u0026thinsp;\u0026plusmn;\u0026thinsp;0.57\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e5.68\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAspartic acid\u0026thinsp;+\u0026thinsp;Asparagine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5.76\u0026thinsp;\u0026plusmn;\u0026thinsp;0.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6.58\u0026thinsp;\u0026plusmn;\u0026thinsp;0.71\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6.58\u0026thinsp;\u0026plusmn;\u0026thinsp;0.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e6.55\u0026thinsp;\u0026plusmn;\u0026thinsp;0.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e6.53\u0026thinsp;\u0026plusmn;\u0026thinsp;0.17\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCysteine (Cys-Cys)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.44\u0026thinsp;\u0026plusmn;\u0026thinsp;0.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.00\u0026thinsp;\u0026plusmn;\u0026thinsp;0.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.13\u0026thinsp;\u0026plusmn;\u0026thinsp;0.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.95\u0026thinsp;\u0026plusmn;\u0026thinsp;0.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1.56\u0026thinsp;\u0026plusmn;\u0026thinsp;0.10\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGlutamic acid\u0026thinsp;+\u0026thinsp;Glutamine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9.12\u0026thinsp;\u0026plusmn;\u0026thinsp;0.76\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9.93\u0026thinsp;\u0026plusmn;\u0026thinsp;1.74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8.54\u0026thinsp;\u0026plusmn;\u0026thinsp;0.36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8.53\u0026thinsp;\u0026plusmn;\u0026thinsp;0.41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e21.27\u0026thinsp;\u0026plusmn;\u0026thinsp;0.52\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGlycine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5.70\u0026thinsp;\u0026plusmn;\u0026thinsp;0.36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6.12\u0026thinsp;\u0026plusmn;\u0026thinsp;0.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5.63\u0026thinsp;\u0026plusmn;\u0026thinsp;0.57\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5.58\u0026thinsp;\u0026plusmn;\u0026thinsp;0.61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4.12\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eProline\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6.28\u0026thinsp;\u0026plusmn;\u0026thinsp;1.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6.73\u0026thinsp;\u0026plusmn;\u0026thinsp;0.94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.25\u0026thinsp;\u0026plusmn;\u0026thinsp;1.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8.97\u0026thinsp;\u0026plusmn;\u0026thinsp;1.45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e8.26\u0026thinsp;\u0026plusmn;\u0026thinsp;0.44\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSerine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7.51\u0026thinsp;\u0026plusmn;\u0026thinsp;1.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7.31\u0026thinsp;\u0026plusmn;\u0026thinsp;0.69\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.48\u0026thinsp;\u0026plusmn;\u0026thinsp;0.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e7.83\u0026thinsp;\u0026plusmn;\u0026thinsp;0.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e6.41\u0026thinsp;\u0026plusmn;\u0026thinsp;0.21\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTaurin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.16\u0026thinsp;\u0026plusmn;\u0026thinsp;0.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.12\u0026thinsp;\u0026plusmn;\u0026thinsp;0.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.40\u0026thinsp;\u0026plusmn;\u0026thinsp;0.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.24\u0026thinsp;\u0026plusmn;\u0026thinsp;0.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.08\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTyrosine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5.65\u0026thinsp;\u0026plusmn;\u0026thinsp;0.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.97\u0026thinsp;\u0026plusmn;\u0026thinsp;0.58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5.39\u0026thinsp;\u0026plusmn;\u0026thinsp;0.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4.98\u0026thinsp;\u0026plusmn;\u0026thinsp;0.19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e3.18\u0026thinsp;\u0026plusmn;\u0026thinsp;0.08\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMethionine sulfoxide\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.22\u0026thinsp;\u0026plusmn;\u0026thinsp;0.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.20\u0026thinsp;\u0026plusmn;\u0026thinsp;0.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.17\u0026thinsp;\u0026plusmn;\u0026thinsp;0.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.31\u0026thinsp;\u0026plusmn;\u0026thinsp;0.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.04\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHydroxyproline\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.36\u0026thinsp;\u0026plusmn;\u0026thinsp;0.66\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.83\u0026thinsp;\u0026plusmn;\u0026thinsp;1.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.87\u0026thinsp;\u0026plusmn;\u0026thinsp;0.57\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.35\u0026thinsp;\u0026plusmn;\u0026thinsp;0.60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.09\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHydroxylysine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.96\u0026thinsp;\u0026plusmn;\u0026thinsp;0.58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.13\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.13\u0026thinsp;\u0026plusmn;\u0026thinsp;0.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.59\u0026thinsp;\u0026plusmn;\u0026thinsp;0.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.10\u0026thinsp;\u0026plusmn;\u0026thinsp;0.09\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eΣNEAAs\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e52.45\u0026thinsp;\u0026plusmn;\u0026thinsp;0.58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e53.27\u0026thinsp;\u0026plusmn;\u0026thinsp;1.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e52.12\u0026thinsp;\u0026plusmn;\u0026thinsp;0.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e54.82\u0026thinsp;\u0026plusmn;\u0026thinsp;0.70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e57.31\u0026thinsp;\u0026plusmn;\u0026thinsp;0.70\u003csup\u003ex\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe total FA content (mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e DW) of sludge samples taken at different depths and different cages was not significantly different from each other (Welch\u0026rsquo;s t-test, p\u0026thinsp;\u0026ge;\u0026thinsp;0.05, Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Fish feed had a significantly higher FA content than sludge samples (one-way ANOVA, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). No differences were detected in relative content of ΣSAFAs, ΣMUFAs, and ΣPUFAs (% of total FAs) when comparing sludge samples from different depths and different cages (Welch\u0026rsquo;s t-test, p\u0026thinsp;\u0026ge;\u0026thinsp;0.05, Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). The proportion of SAFAs in fish feed was significantly lower compared to sludge samples, while the proportion of PUFAs was significantly higher (one-way ANOVA, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). The proportion of MUFAs contained in fish feed was not significantly different from that in sludge samples (one-way ANOVA, p\u0026thinsp;\u0026ge;\u0026thinsp;0.05). The FAs with the largest proportions in both sludge and fish feed were oleic acid (C18:1 n-9), linoleic acid (C18:2 n-6), palmitic acid (C16:0) and stearic acid (C18:0). There were no differences in percentages of arachidonic acid (ARA; C20:4 n-6), eicosapentaenoic acid (EPA, C20:5 n-3), and docosahexaenoic acid (DHA, C22:6 n-3) between the sludge samples from different depths and different cages. The percentage of EPA and DHA in fish feed was significantly higher than in sludge samples, while the proportion of ARA was not significantly different. PCA showed that relative FA composition (% of total FAs) of sludge samples was not affected by sampling depth. However, it was impacted by the position of the cages at the farm to some extent (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Differences in variance of FA composition were smaller between the different sludge samples than when comparing sludge samples to fish feed. PC1 and PC2 combined explained 79% of the variance in the FA data set.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eRelative fatty acid (FA) composition (% of total FAs) of sludge collected from sediment traps below Atlantic salmon sea cages, Cage 1 \u0026ndash; Top, Cage 1 \u0026ndash; Bottom, Cage 2 \u0026ndash; Top, and Cage 2 \u0026ndash; Bottom (n\u0026thinsp;=\u0026thinsp;3) and fish feed (n\u0026thinsp;=\u0026thinsp;2). SAFAs\u0026thinsp;=\u0026thinsp;saturated FAs, MUFAs\u0026thinsp;=\u0026thinsp;monounsaturated FAs, PUFAs\u0026thinsp;=\u0026thinsp;polyunsaturated FAs. \u003csup\u003ex\u003c/sup\u003e denotes a significant difference of fish feed from sludge samples.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCage 1\u003c/p\u003e \u003cp\u003eTop\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCage 1\u003c/p\u003e \u003cp\u003eBottom\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCage 2\u003c/p\u003e \u003cp\u003eTop\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCage 2\u003c/p\u003e \u003cp\u003eBottom\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eFish feed\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTotal FAs (mg g\u003c/b\u003e\u003csup\u003e\u003cb\u003e\u0026minus;\u0026thinsp;1\u003c/b\u003e\u003c/sup\u003e \u003cb\u003eDW)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e56.04\u0026thinsp;\u0026plusmn;\u0026thinsp;21.71\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e53.91\u0026thinsp;\u0026plusmn;\u0026thinsp;14.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e80.11\u0026thinsp;\u0026plusmn;\u0026thinsp;17.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e86.19\u0026thinsp;\u0026plusmn;\u0026thinsp;33.88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e225.64\u0026thinsp;\u0026plusmn;\u0026thinsp;13.44\u003csup\u003ex\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e% of total FAs\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC14:0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e2.96\u0026thinsp;\u0026plusmn;\u0026thinsp;0.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e2.86\u0026thinsp;\u0026plusmn;\u0026thinsp;0.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e2.72\u0026thinsp;\u0026plusmn;\u0026thinsp;0.15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e2.71\u0026thinsp;\u0026plusmn;\u0026thinsp;0.31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2.02\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC15:0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.33\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.32\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e0.26\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e0.27\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.18\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC16:0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e19.06\u0026thinsp;\u0026plusmn;\u0026thinsp;3.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e18.37\u0026thinsp;\u0026plusmn;\u0026thinsp;1.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e15.43\u0026thinsp;\u0026plusmn;\u0026thinsp;1.28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e15.70\u0026thinsp;\u0026plusmn;\u0026thinsp;2.82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e10.10\u0026thinsp;\u0026plusmn;\u0026thinsp;0.03\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC17:0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.53\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.50\u0026thinsp;\u0026plusmn;\u0026thinsp;0.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e0.36\u0026thinsp;\u0026plusmn;\u0026thinsp;0.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e0.31\u0026thinsp;\u0026plusmn;\u0026thinsp;0.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.20\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC18:0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e24.31\u0026thinsp;\u0026plusmn;\u0026thinsp;2.66\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e20.88\u0026thinsp;\u0026plusmn;\u0026thinsp;2.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e16.76\u0026thinsp;\u0026plusmn;\u0026thinsp;0.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e16.17\u0026thinsp;\u0026plusmn;\u0026thinsp;2.21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4.09\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC20:0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e1.55\u0026thinsp;\u0026plusmn;\u0026thinsp;0.24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e1.45\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e1.31\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e1.37\u0026thinsp;\u0026plusmn;\u0026thinsp;0.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.46\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC22:0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.94\u0026thinsp;\u0026plusmn;\u0026thinsp;0.41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.95\u0026thinsp;\u0026plusmn;\u0026thinsp;0.36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e0.73\u0026thinsp;\u0026plusmn;\u0026thinsp;0.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e0.84\u0026thinsp;\u0026plusmn;\u0026thinsp;0.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.29\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eΣSAFAs\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e49.68\u0026thinsp;\u0026plusmn;\u0026thinsp;6.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e45.33\u0026thinsp;\u0026plusmn;\u0026thinsp;1.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e37.56\u0026thinsp;\u0026plusmn;\u0026thinsp;1.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e37.36\u0026thinsp;\u0026plusmn;\u0026thinsp;5.94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e17.35\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003csup\u003ex\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC14:1 n-5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.05\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.05\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e0.06\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e0.05\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.06\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC16:1 n-9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.14\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.14\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e0.12\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e0.13\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.11\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC16:1 n-7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e1.87\u0026thinsp;\u0026plusmn;\u0026thinsp;0.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e1.96\u0026thinsp;\u0026plusmn;\u0026thinsp;0.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e2.20\u0026thinsp;\u0026plusmn;\u0026thinsp;0.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e2.14\u0026thinsp;\u0026plusmn;\u0026thinsp;0.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2.46\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC16:1 n-5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.22\u0026thinsp;\u0026plusmn;\u0026thinsp;0.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.22\u0026thinsp;\u0026plusmn;\u0026thinsp;0.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e0.17\u0026thinsp;\u0026plusmn;\u0026thinsp;0.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e0.21\u0026thinsp;\u0026plusmn;\u0026thinsp;0.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.15\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC18:1 n-9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e24.61\u0026thinsp;\u0026plusmn;\u0026thinsp;4.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e26.72\u0026thinsp;\u0026plusmn;\u0026thinsp;1.45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e32.37\u0026thinsp;\u0026plusmn;\u0026thinsp;1.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e33.56\u0026thinsp;\u0026plusmn;\u0026thinsp;4.57\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e38.03\u0026thinsp;\u0026plusmn;\u0026thinsp;0.21\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC18:1 n-7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e2.38\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e2.52\u0026thinsp;\u0026plusmn;\u0026thinsp;0.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e2.94\u0026thinsp;\u0026plusmn;\u0026thinsp;0.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e2.96\u0026thinsp;\u0026plusmn;\u0026thinsp;0.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2.41\u0026thinsp;\u0026plusmn;\u0026thinsp;0.03\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC20:1 n-9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e3.22\u0026thinsp;\u0026plusmn;\u0026thinsp;0.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e3.32\u0026thinsp;\u0026plusmn;\u0026thinsp;0.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e4.26\u0026thinsp;\u0026plusmn;\u0026thinsp;0.41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e4.22\u0026thinsp;\u0026plusmn;\u0026thinsp;0.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2.98\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC22:1 n-11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.52\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.52\u0026thinsp;\u0026plusmn;\u0026thinsp;0.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e0.63\u0026thinsp;\u0026plusmn;\u0026thinsp;0.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e0.63\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.31\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC22:1 n-9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e3.09\u0026thinsp;\u0026plusmn;\u0026thinsp;0.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e3.10\u0026thinsp;\u0026plusmn;\u0026thinsp;0.36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e3.78\u0026thinsp;\u0026plusmn;\u0026thinsp;0.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e3.73\u0026thinsp;\u0026plusmn;\u0026thinsp;0.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2.58\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC24:1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.88\u0026thinsp;\u0026plusmn;\u0026thinsp;0.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.83\u0026thinsp;\u0026plusmn;\u0026thinsp;0.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e0.77\u0026thinsp;\u0026plusmn;\u0026thinsp;0.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e0.75\u0026thinsp;\u0026plusmn;\u0026thinsp;0.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.29\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eΣMUFAs\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e36.97\u0026thinsp;\u0026plusmn;\u0026thinsp;5.35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e39.38\u0026thinsp;\u0026plusmn;\u0026thinsp;1.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e47.3\u0026thinsp;\u0026plusmn;\u0026thinsp;0.82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e48.37\u0026thinsp;\u0026plusmn;\u0026thinsp;5.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e49.39\u0026thinsp;\u0026plusmn;\u0026thinsp;0.25\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC16:2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.05\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.07\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e0.10\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e0.10\u0026thinsp;\u0026plusmn;\u0026thinsp;0.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.18\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC18:2 n-6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e7.65\u0026thinsp;\u0026plusmn;\u0026thinsp;0.85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e8.64\u0026thinsp;\u0026plusmn;\u0026thinsp;1.41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e8.73\u0026thinsp;\u0026plusmn;\u0026thinsp;0.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e8.19\u0026thinsp;\u0026plusmn;\u0026thinsp;0.60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e15.59\u0026thinsp;\u0026plusmn;\u0026thinsp;0.26\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC18:3 n-3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e1.87\u0026thinsp;\u0026plusmn;\u0026thinsp;0.52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e2.31\u0026thinsp;\u0026plusmn;\u0026thinsp;0.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e2.64\u0026thinsp;\u0026plusmn;\u0026thinsp;0.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e2.38\u0026thinsp;\u0026plusmn;\u0026thinsp;0.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e8.32\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC18:4 n-3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.27\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.33\u0026thinsp;\u0026plusmn;\u0026thinsp;0.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e0.29\u0026thinsp;\u0026plusmn;\u0026thinsp;0.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e0.29\u0026thinsp;\u0026plusmn;\u0026thinsp;0.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.83\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC20:2 n-6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.23\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.22\u0026thinsp;\u0026plusmn;\u0026thinsp;0.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e0.24\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e0.23\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.11\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC20:4 n-6 ARA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.25\u0026thinsp;\u0026plusmn;\u0026thinsp;0.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.34\u0026thinsp;\u0026plusmn;\u0026thinsp;0.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e0.12\u0026thinsp;\u0026plusmn;\u0026thinsp;0.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e0.18\u0026thinsp;\u0026plusmn;\u0026thinsp;0.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.28\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC20:3 n-3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.06\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.06\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e0.06\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e0.06\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.05\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC20:5 n-3 EPA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.57\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.81\u0026thinsp;\u0026plusmn;\u0026thinsp;0.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e0.66\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e0.58\u0026thinsp;\u0026plusmn;\u0026thinsp;0.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e3.52\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003csup\u003ex\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC22:5 n-3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.71\u0026thinsp;\u0026plusmn;\u0026thinsp;0.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.72\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e0.65\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e0.75\u0026thinsp;\u0026plusmn;\u0026thinsp;0.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.77\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC22:6 n-3 DHA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e1.69\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e1.79\u0026thinsp;\u0026plusmn;\u0026thinsp;0.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e1.66\u0026thinsp;\u0026plusmn;\u0026thinsp;0.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e1.48\u0026thinsp;\u0026plusmn;\u0026thinsp;0.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e3.60\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04\u003csup\u003ex\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eΣPUFAs\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e13.35\u0026thinsp;\u0026plusmn;\u0026thinsp;1.41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e15.29\u0026thinsp;\u0026plusmn;\u0026thinsp;2.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e15.15\u0026thinsp;\u0026plusmn;\u0026thinsp;1.53\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e14.26\u0026thinsp;\u0026plusmn;\u0026thinsp;1.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e33.26\u0026thinsp;\u0026plusmn;\u0026thinsp;0.26\u003csup\u003ex\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eΣn-3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e5.17\u0026thinsp;\u0026plusmn;\u0026thinsp;0.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e6.02\u0026thinsp;\u0026plusmn;\u0026thinsp;0.83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e5.95\u0026thinsp;\u0026plusmn;\u0026thinsp;0.61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e5.55\u0026thinsp;\u0026plusmn;\u0026thinsp;0.55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e17.09\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eΣn-6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e8.13\u0026thinsp;\u0026plusmn;\u0026thinsp;0.82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e9.20\u0026thinsp;\u0026plusmn;\u0026thinsp;1.31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e9.09\u0026thinsp;\u0026plusmn;\u0026thinsp;0.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e8.61\u0026thinsp;\u0026plusmn;\u0026thinsp;0.58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e15.98\u0026thinsp;\u0026plusmn;\u0026thinsp;0.26\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDHA/EPA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e5.91\u0026thinsp;\u0026plusmn;\u0026thinsp;2.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e4.49\u0026thinsp;\u0026plusmn;\u0026thinsp;0.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e3.21\u0026thinsp;\u0026plusmn;\u0026thinsp;0.56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e3.39\u0026thinsp;\u0026plusmn;\u0026thinsp;1.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.45\u0026thinsp;\u0026plusmn;\u0026thinsp;0.03\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"4 Discussion","content":"\u003cp\u003eOur results show that varying feed input at different cages at the aquaculture site \u0026ldquo;Lam\u0026oslash;ya\u0026rdquo; lead to different quantities of sludge collected in the sediment traps, with a strong correlation between feed input and collected sludge and with no difference in the proportion of sludge that sedimented, when comparing the two different cages. Contrary to our hypothesis, we found no difference between sludge quantities collected at 39 m and 44 m water depth, suggesting a limited effect of ocean current on sludge sedimentation between these sampling points. This argumentation is supported by the site report of the studied site, in which average ocean current speeds of 8.0 cm s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 3.9 cm s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e were recorded at 5 m and 15 m depth, respectively (Havbrukstjenesten, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2013\u003c/span\u003e), showing a decrease in current speed with increasing depth.\u003c/p\u003e \u003cp\u003eThe quantification of sludge collected in this study confirms that, overall, only a small fraction of the sludge that is theoretically produced in salmon aquaculture sediments directly beneath the sea cages. The sedimented proportion that was calculated based on sludge collected by sediment traps was 10\u0026ndash;15% of the total theoretically produced sludge, implying that most of the sludge is spread in proximity of farms, with the dispersal being influenced by environmental conditions and ocean currents (Law and Hill, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2019\u003c/span\u003e, Carvajalino-Fernandez et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Simulations by Broch et al. (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2017\u003c/span\u003e) found that waste sludge from salmon cages sediments up to at least 500 m away from the farm and would hence not be registered in B-investigations which are carried out directly beneath the aquaculture site (Fiskeridirektoratet, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2023a\u003c/span\u003e). Our findings of only low sedimentation directly beneath the sea cages, are supported by the latest B- and C-investigation that were conducted at the studied site. The B-investigation classified the general condition under the farm as 1 \u0026ndash; very good, with no sludge being registered in any of the 13 grab samples and the benthic ecosystem being evaluated as healthy, with a turnover rate sufficient enough for the seafloor not to be negatively impacted by sludge dispersed from the salmon cages (\u0026Aring;kerbl\u0026aring;, \u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Results from the most recent C-investigation gave a \u0026ldquo;moderate\u0026rdquo; score with the highest organic matter load found southeast of the farm and the dispersal following the main current direction (Havbrukstjenesten, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2013\u003c/span\u003e, \u0026Aring;kerbl\u0026aring;, \u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe quantity of sedimented sludge in this study may however have been affected by the presence of wild fish. Floating structures such as salmon farms have been described as fish aggregation devices (FADs), meaning wild fish aggregate around them to feed on uneaten feed (Dempster et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2009\u003c/span\u003e, Sanchez-Jerez et al., \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). Biomass estimates of wild fish underneath sea cages range from 10\u0026ndash;100 tonnes which would have a significant impact on quantity of sludge that sediments to the sea floor as they a large proportion of feed pellets would be consumed before they can sediment sink down (S\u0026aelig;ther et al., \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2013\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFinally, some uncertainties in our quantification results due to the used method cannot be excluded. When calculating the theoretical mass of produced sludge, a proportion of 13% feed spill was used, following Aas and \u0026Aring;sg\u0026aring;rd (\u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). However, other studies have reported considerably lower numbers of 3\u0026ndash;5% (Reid, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2007\u003c/span\u003e, Wang et al., \u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e2012\u003c/span\u003e, Wang et al., \u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e2013\u003c/span\u003e), suggesting a potential overestimation in the calculation of theoretically produced sludge in our study. Moreover, numbers of digestibility and defecation ratios vary. Wang and Olsen (\u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) reported a defecation ratio of 18% as opposed to 30% which were used in this study based on numbers from Aas and \u0026Aring;sg\u0026aring;rd (\u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). Additionally, the trap area was small compared to the total cage area which implicates that only small deviations in the mass of collected sludge would have a large effect on the calculated mass of sedimented sludge.\u003c/p\u003e \u003cp\u003eWhen comparing the composition of sludge from sea-based salmon cages with that of land-based production, some differences were found. The ash content of sludge samples collected under the salmon farm was similar to that of sludge from land-based smolt production reported by Wang et al. (\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2019a\u003c/span\u003e), while Anglade et al. (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2023b\u003c/span\u003e) reported a lower ash content for post-smolt sludge from brackish water production and a substantially lower ash content of smolt sludge collected from freshwater. Samples from a saline environment often exhibit a higher ash content due to a higher concentration of dissolved minerals and salts compared to freshwater. Since our study was conducted at open sea, the ash content of our samples could have further been elevated by shell, silt, and sand particles\u0026thinsp;\u0026lt;\u0026thinsp;200 \u0026micro;m which were not removed during sample filtration (Nagao et al., \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2001\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eValues of C and P content of sludge samples were substantially lower than those reported by Anglade et al. (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2023a\u003c/span\u003e), however when considering the differences in ash content and regarding the numbers as proportion of total organic matter (TOM), they fell within a comparable range. Further, the P content of sludge was similar to that of salmon feces (Wang et al., \u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). N, protein, and AA content was lower than that of sludge from land-based salmon production (Wang et al., \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2019a\u003c/span\u003e, Anglade et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2023b\u003c/span\u003e, \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2023a\u003c/span\u003e) which can be explained by the changes in feed requirements for salmon and the correlated change in feces composition. In early life stages, salmon depend on a higher proportion of protein to support rapid growth and development (Nordgarden et al., \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2002\u003c/span\u003e). As the fish age and go through transition to seawater environments, lipid requirements increase as lipid storage is crucial for maintaining buoyancy and thermal regulation (Sargent et al., \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2002\u003c/span\u003e). Accordingly, the feed composition is adapted in farmed salmon (EWOS, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2022b\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2022a\u003c/span\u003e) and therefore, sludge from earlier life stages may have a higher protein, AA, and N content but a lower lipid and FA content. Lipid content of sludge collected in our study was similar or higher to that reported in previous studies (Wang 2013, Wang 2019, Anglade 2019a), while the FA content was slightly lower. However, the lipid content of fish feed analyzed in this study was significantly lower than indicated by the producer (EWOS, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2022a\u003c/span\u003e), suggesting that lipid and FA content of both fish feed and sludge may have been undervalued in our analyses.\u003c/p\u003e \u003cp\u003eLipid and protein content of sludge are moreover likely to have been affected by fish health. Prior to our study, salmon at the farm were diagnosed with pancreatic disease (PD) (BarentsWatch, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Among other symptoms, PD caused by SAV2 leads to reduced appetite in salmon and can decrease both protein and lipid digestibility of feed (R\u0026oslash;s\u0026aelig;g et al., \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2019\u003c/span\u003e), and, as a result, change the composition of feces and sludge. PCA revealed no effect of sampling location or depth on AA composition, however, a grouping of cages in the PCA plot was observed for FA composition. This may have either been influenced by the health status of the fish and the associated feed digestibility or a different proportion of feed spill in the cages.\u003c/p\u003e \u003cp\u003eAs described previously, a potentially large proportion of feed pellets from salmon farms may be consumed by wild fish that aggregate around the cages (Dempster et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2009\u003c/span\u003e, Uglem et al., \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). This does not only impact the quantity of sedimented sludge but also the composition. As reported by Wang et al. (\u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e2013\u003c/span\u003e), feed pellets have a higher nutritional value than salmon feces as they have a higher C, N, P, and lipid content. A smaller proportion of feed in sludge would explain the lower nutrient density of sludge collected in this trial compared to sludge from land-based aquaculture (Wang et al., \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2019a\u003c/span\u003e, Anglade et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2023b\u003c/span\u003e, Anglade et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2023a\u003c/span\u003e). Additionally, feed spill in land-based aquaculture has been reported to be higher compared to sea-based aquaculture (Aas and \u0026Aring;sg\u0026aring;rd, \u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e2017\u003c/span\u003e) which would also lead to a higher proportion of feed to feces in sludge and hence a higher nutritional value of sludge from land-based aquaculture.\u003c/p\u003e \u003cp\u003eOverall, there was no significant difference in ash, C, N, P, lipid, FA, protein, or AA content of sludge samples from different depths and different cages, suggesting that the composition of sludge that sedimented from salmon cages was independent of location at the farm or sampling depth within the scope of this study. However, more research is necessary to assess how seasonal variation (Wang and Olsen, \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) and factors such as salmon size and health status affect quality of sludge that sediments from salmon cages.\u003c/p\u003e \u003cp\u003eAlthough the majority of surveyed aquaculture sites scored highly in B- and C-investigations in the past (Fiskeridirektoratet, 2016, BarentsWatch, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2023\u003c/span\u003e), an increasing emphasis is placed on the environmental effects of high organic matter loading, especially with a continuously growing industry. Alongside other challenges such as diseases and escapees (Lekang et al., \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2016\u003c/span\u003e, Olaussen, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), a future scenario where salmon are cultivated in sea-based closed-containment systems becomes increasingly relevant. Closed-containment systems provide a more controlled environment, reducing the risk of disease transmission between farmed and wild fish. Further, they provide a physical barrier that reduces the risk of fish escapes and can help mitigate the environmental impact of salmon farming by preventing the direct release of nutrients, chemicals, and waste into surrounding waters as all intake and effluent water is filtrated (Rosten et al., \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2011\u003c/span\u003e, Nilsen, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Though sludge from sea-based aquaculture may have a lower nutritional value than sludge from land-based production, cultivation in closed-containment systems would result in immense quantities of collected sludge that adequate applications are required for. Sludge from land-based aquaculture is currently used for biogas production, however, the salt content of saline sludge from sea-based production can change the bacterial community during biogas production and thus decrease biogas yield (Gebauer, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2004\u003c/span\u003e, Mirzoyan et al., \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). Additionally dewatering such large volumes of sludge would result in high energy consumption (Del Campo et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2010\u003c/span\u003e, Aas and \u0026Aring;sg\u0026aring;rd, \u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e2017\u003c/span\u003e) which makes it apparent that there is a need for alternative solutions.\u003c/p\u003e \u003cp\u003eFollowing an IMTA approach, nutrient-rich waste sludge from salmon aquaculture can be utilized by lower trophic organisms such as polychaetes, as demonstrated by several studies (Nederlof et al., \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2019\u003c/span\u003e, Wang et al., \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2019a\u003c/span\u003e, Anglade et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2023b\u003c/span\u003e). Whether the composition of the sludge collected in this study could be suited for it to be used as a diet for polychaetes \u003cem\u003eH. diversicolor\u003c/em\u003e depends upon different factors. In general, the nutrient composition and elemental ratios of organisms like \u003cem\u003eH. diversicolor\u003c/em\u003e serve as a reliable indicator of their dietary nutrient needs (Sterner and Schulz, \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e1998\u003c/span\u003e, Wagner et al., \u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). Due to a low N content of sludge collected in this study, the C:N ratio was substantially higher than that of sludge used for cultivation of polychaetes in other studies (Wang et al., \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2019a\u003c/span\u003e, Anglade et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2023a\u003c/span\u003e). Further, the N:P ratio of sludge was half that of sludge from land-based salmon production, which may affect efficient utilization of P. As N, AA and protein content were identified to promote polychaete growth (Santos et al., \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2016\u003c/span\u003e, Wang et al., \u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e2019b\u003c/span\u003e), \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003ea\u003c/span\u003e low content in sludge collected in our study, when comparing to previous trials, may pose a challenge and lead to reduced growth in \u003cem\u003eH. diversicolor\u003c/em\u003e when fed with sludge from sea-based aquaculture as a sole feed source. In previous studies, the lipid content of \u003cem\u003eH. diversicolor\u003c/em\u003e was strongly positively correlated with the lipid content of their diet. Since the lipid content of sludge collected in this study was similar or higher than that of sludge used by Wang et al. (\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2019a\u003c/span\u003e) and Anglade et al. (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2023b\u003c/span\u003e), it can be considered appropriate for cultivation of the species. Although Anglade et al. (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2023b\u003c/span\u003e) reported no significant effect of a different ash content between smolt and post-smolt sludge on composition and growth on polychaetes, it should be considered whether the higher ash and associated salt content in sludge from sea-based aquaculture compared to sludge from land-based smolt and post-smolt production could affect digestibility in \u003cem\u003eH. diversicolor\u003c/em\u003e.\u003c/p\u003e \u003cp\u003eIn summary, sludge from sea-based production collected in this study is probable to be an appropriate diet and the application should be investigated further in laboratory trials. An alternative to cultivation of \u003cem\u003eH. diversicolor\u003c/em\u003e with sludge collected from sea-based salmon aquaculture would be a direct integration of naturally under salmon farm occurring polychaetes species such as \u003cem\u003eCapitella\u003c/em\u003e sp. and \u003cem\u003eOphryotrocha craigsmithi\u003c/em\u003e, building on research by Kinoshita et al. (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2008\u003c/span\u003e), Nederlof et al. (\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2019\u003c/span\u003e), and Nederlof et al. (\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). These species could be produced at high densities with a large biomass output (Tsutsumi et al., \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e2005\u003c/span\u003e) but, although initial efforts for a sea-based cultivation have been made, technical restraints persist and methods for cultivating and harvesting marine polychaetes beneath salmon farms have not been established (Jansen et al., \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2019\u003c/span\u003e, Nederlof et al., \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e"},{"header":"5 Conclusion","content":"\u003cp\u003eOur findings confirmed the hypothesis that the quantity of sedimented sludge will be different at different salmon cages at the same aquaculture site, with a strong positive correlation of feed input and sludge collection. The sedimented percentage of sludge as a proportion of theoretically produced sludge was similar for both cages and depths. Sampling depth did not affect the collected sludge quantity, suggesting a limited impact of ocean current underneath the sea cages at this specific location. With the exemption of FA composition, which seemed slightly affected by cage location, the composition of sedimented sludge was comparable across the salmon farm, with no significant difference of ash, C, N, P, lipid, FA, protein, or AA content between the different cages and sampling depths. The suitability of sludge collected in this study for cultivation of \u003cem\u003eH. diversicolor\u003c/em\u003e using an IMTA approach was assessed theoretically, and although sludge collected from sea-based salmon production was found to have a lower nutritional value than that from land-based aquaculture, it could likely serve as a feed resource for production of polychaete biomass. Further confirmation in applied studies is, however, necessary.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eFunding\u003c/p\u003e\n\u003cp\u003eWe acknowledge funding by the RCN projects POLYCHAETE (#280836) and MIND-P (#268338) and would like to thank M\u0026aring;s\u0026oslash;val AS for their assistance and enabling this study.\u003c/p\u003e\n\u003cp\u003eCompeting Interests\u003c/p\u003e\n\u003cp\u003eThe authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.\u003c/p\u003e\n\u003cp\u003eAuthor Contributions\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eIA:\u0026nbsp;\u003c/strong\u003eConceptualization, Data curation, Formal analysis, Investigation, Visualization, Writing \u0026ndash; original draft, Writing \u0026ndash; review \u0026amp; editing. \u003cstrong\u003eTMK:\u003c/strong\u003e Formal analysis, Investigation, Writing \u0026ndash; review. \u003cstrong\u003eKIR:\u0026nbsp;\u003c/strong\u003eConceptualization, Investigation,\u0026nbsp;Project administration, Funding acquisition, Supervision, Writing \u0026ndash; review \u0026amp; editing.\u003c/p\u003e\n\u003cp\u003eData Availability Statement\u003c/p\u003e\n\u003cp\u003eThe raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAnglade I, Kristensen BSB, Dahl TH, Hagemann A, Malzahn AM, Reitan KI (2023a) Upcycling of carbon, nitrogen, and phosphorus from aquaculture sludge using the polychaete \u003cem\u003eHediste diversicolor\u003c/em\u003e (OF M\u0026uuml;ller, 1776) (Annelida: Nereididae). 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Nofima rapportserie 19 (2017), 1\u0026ndash;8\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"","identity":"aquaculture-international","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"10499","submissionUrl":"https://submission.nature.com/new-submission/10499/3","title":"Aquaculture International","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"","reportingPortfolio":"VoR Journals","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Atlantic salmon, salmon aquaculture, aquaculture sludge, nutrient dispersal, lipids, fatty acids, amino acids","lastPublishedDoi":"10.21203/rs.3.rs-3969754/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3969754/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eFuture growth of Atlantic salmon (\u003cem\u003eSalmo salar\u003c/em\u003e L.) in Norway is tied to finding solutions for major ecological challenges connected to salmon lice, escapees, and nutrient emissions from sea cages. At the same time, nutrient-rich sludge from salmon production comprises a valuable resource for the cultivation of lower trophic species using an integrated multi-trophic aquaculture (IMTA) approach. This study aimed to quantify the sedimentation of waste sludge under sea cages of an Atlantic salmon aquaculture site and to qualify the composition of this sludge. Additionally, the study evaluated the potential use of sludge from sea-based aquaculture as a feed source for polychaetes \u003cem\u003eHediste diversicolor\u003c/em\u003e.\u003c/p\u003e \u003cp\u003eUsing sediment traps, sludge samples were collected from two different sea cages, at two different depths, and three different sampling dates. Subsequently, they were quantified, and their composition was assessed with regards to carbon, nitrogen, phosphorus, lipid, fatty acid, protein, amino acid, and ash content as well as elemental ratios and composition of fatty acids and amino acids.\u003c/p\u003e \u003cp\u003eThe quantity of collected sludge was significantly different between sea cages, with a strong positive correlation between feed input and collected sludge. Sampling depth did not affect the quantity of collected sludge. No significant difference in the proportion of sedimented sludge as a proportion of theoretically produced sludge was found when comparing the different cages and sampling depths. Further, the composition of collected sludge was similar at all sampling points. The overall nutritional value was lower compared to sludge from land-based aquaculture, regardless, sludge from sea-based salmon production can in theory be considered as a potential feed resource to be used for the production of polychaetes \u003cem\u003eH. diversicolor\u003c/em\u003e.\u003c/p\u003e","manuscriptTitle":"Sludge from sea-based Atlantic salmon (Salmo salar L.) production: quantification, composition, and potential application in IMTA","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-02-21 11:24:39","doi":"10.21203/rs.3.rs-3969754/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-03-18T19:16:33+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-03-02T10:28:09+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"80c0f73b-43c7-42de-bdc0-005f0ca5977d","date":"2024-02-29T19:48:36+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-02-21T09:57:21+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-02-21T09:55:16+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-02-20T04:13:31+00:00","index":"","fulltext":""},{"type":"submitted","content":"Aquaculture International","date":"2024-02-19T10:37:03+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"","identity":"aquaculture-international","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"10499","submissionUrl":"https://submission.nature.com/new-submission/10499/3","title":"Aquaculture International","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"","reportingPortfolio":"VoR Journals","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"e9a392b8-8acf-4ba8-875b-66cc7713d418","owner":[],"postedDate":"February 21st, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2024-03-25T10:48:20+00:00","versionOfRecord":[],"versionCreatedAt":"2024-02-21 11:24:39","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3969754","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3969754","identity":"rs-3969754","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}