Assessment of Sediment Quality and Vulnerability of Tropical Marine Species in the Society Islands, French Polynesia

Assessment of Sediment Quality and Vulnerability of Tropical Marine Species in the Society Islands, French Polynesia | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Assessment of Sediment Quality and Vulnerability of Tropical Marine Species in the Society Islands, French Polynesia Francois Galgani, Maelys Jouet, Maeva Goulais, Nono-lewis Tetaura, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6711214/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Aquatic sediments act as reservoirs of multiple sources of pollutants, and the increasing urbanization of coastal marine areas generally contributes to the accumulation of contaminants, endangering aquatic life and biodiversity. In the present study, we assessed the toxicity of sediment sampled at 150 sites around six islands in the Society Archipelago, French Polynesia. This evaluation is based on the use of standardized biological assays, during larval development of tropical benthic species systems in sediment elutriates. The results have shown a significant correlation in the responses of the four species studied: the oyster Saccostrea cucculata, the sea cucumber Holothuria fuscogilva, the sea urchin Tripneustes gratilla, and the shrimp Litopenaeus stylirostris. Larvae of Holothuria fuscogilva and Tripneustes gratilla were the most sensitive and suitable for assessing sediment quality. Data mapping revealed high toxicity, up to 100% mortality of larvae, in selected sites such as the Vaitepiha river mouth, Titaaviri, Atimaono in Tahiti Islans, as well as ‘Ōpūnohu Bay, Cook Bay, and Haapiti Bay in Moorea, and lake Maeva in Huahine. This toxicity is attributable to various sources of pollution, including agricultural, urban runoff and industrial effluents, as well as harbor and leisure activities. This study provides a significant contribution by identifying species that will provide essential predictive tools for adaptive management of tropical lagoons and identifying areas that showed high rates of developmental anomalies, requiring increased monitoring. Ecotoxicology Bioassays Sediments Indicators Reef ecosystems French Polynesia Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Highlights The first large-scale use of toxicity tests to map sediment quality in French Polynesia. The first use ever of the white sea cucumber species ( Holothuria fuscogilva ) for toxicity tests. The study highlights sediment toxicity in certain polluted sites of the Society Archipelago. The echinoderms Holothuria fuscogilva and Tripneustes gratilla were the most sensitive. Introduction Aquatic ecosystems worldwide are increasingly threatened by the accumulation of anthropogenic pollutants stemming from industrial, urban, and agricultural activities. These contaminants pose significant risks to environmental and human health due to their persistence and potentially harmful effects on aquatic organisms and ecosystems (review in Hadji & Lucas, 2024). Sediments, acting as natural sinks for pollutants in aquatic environments, play a crucial role in the accumulation and storage of contaminants over time, also acting as reservoirs for various toxic compounds like heavy metals, organic pollutants, and microplastics (Ruocco et al., 2020 ; Gambardella et al., 2021 ; Leistenschneider et al., 2023 ; Hama Aziz et al., 2023 ). Furthermore, resuspension of contaminated sediments by storms or dredging operations can increase the bioavailability of contaminated particles. This process contributes to the accumulation of toxic substances and can engender long-term effects on sediment-associated living communities (Schiwy et al., 2022). While the assessment of sediment quality has become imperative for many countries where human activities are intense (Boulanger et al., 2019 ), ecotoxicology is key for understanding the impacts of pollutants on aquatic environments, offering multidisciplinary approaches to assess ecological risks of contaminated sediments (Gambardella et al., 2022 ). Standardized toxicity tests and biological assays are commonly used to evaluate sediment quality and the potential toxic effects of pollutants on aquatic organisms (Bonaventura et al., 2021 ; Broccoli et al., 2021 ) with larvae of bivalves, echinoderms and decapods often used due to their sensitivity (Reguera et al., 2018 ; Gambardella et al., 2021 ). In recent years, significant advancements have been made in ecotoxicology, including the study of particle and plastic toxicity (Leistenschneider et al., 2023 ) and emergent contaminants (Hodge et al., 2025 ), and the integration of molecular biology techniques (metabolomics, mutagenesis, environmental DNA) (Mkuye et al., 2025 ). However, despite these advancements, there is a lack of specific investigations in certain regions, such as French Polynesia where the use of toxicity test has been limited to plastic pollution (Goulais et al., 2024 ; Cruzot et al., 2024). This tropical region is characterized by seasonal climatic conditions, temperature and precipitation variations, and geographical specificities like the dispersion of islands and extensive coral reefs (Andréfouët & Adjeroud, 2019), which can influence the distribution and impact of contaminants in sediments. This study aims to evaluate the potential toxicity of contaminated marine sediments in French Polynesia using bioassays, enumerating anomalies occurring during the larval development of benthic marine species exposed to sediment elutriates from the Society Islands. The results of four bioassays are compared to evaluate local environmental risks, providing early warning indicators to locate contamination risk areas. Among the selected toxicity tests, larval development tests of the oyster ( Saccostrea cucullata ), holothurian ( Holothuria whitmaei ), sea urchin ( Tripneustes gratilla ), and shrimp ( Litopenaeus stylirostris ) were chosen to study the quality of sediment elutriates. These analyses will help formulate testable hypotheses on the causes of sediment pollution in French Polynesia, develop monitoring methodologies, and guide further research to identify the nature of contamination. Materials et Methods Sampling The study covered 150 sites distributed across six islands of the Society archipelago in French Polynesia, South Pacific. Sampling sites included the islands of Tahiti (n = 80), Moorea (n = 15), Huahine (n = 13), Bora Bora (n = 16), Raiatea (n = 17), and Taha'a (n = 9) (Fig. 1 and Supplementary Material SM 1). Sites were selected to represent varying contamination levels, covering diverse areas impacted by various anthropogenic activities, including harbors, tourist areas, river mouths, aquacultutre zones, and reef structures. The maximum depth ranged from a few centimeters to 40 m (Faratea, Tahiti) (Supplementary Material SM 1). Sediment samples were collected between 0.5 cm and 40m depth, over a period of three weeks, from 10/01/2024 to 26/01/2024. Approximately 100g of the top 3 centimeters of sediment were collected using polypropylene tubes and Van veen grab depending on the depth, and preserved in 50ml Falcon tubes. Surface sediments were double-sampled at each site to account for potential loss and more representativeness. Once collected, sediment samples were stored in a refrigerated cooler with ice and transported to the laboratory where they were stored at 4°C for a maximum of three weeks before being used for elutriate preparation, as polluted sediments may maintain their toxicity for over four weeks (Beiras et al., 2009). Spatial coordinates of each sampled site were recorded using GPSMAP 78 for a precise mapping of the study results. Larval development test The seawater used for all experiments, pumped from the Vairao lagoon (Tahiti, French Polynesia), was filtered (25µm, 5µm, and 1µm), treated by UVs, autoclaved, and the stability of water salinity was checked. The sediment extraction step was adapted from the protocol used by Galgani & Baldi. (2010), derived from AFNOR T90 XP-283 (2009), updated in 2015 (ISO standard procedure 17244:2015, under review). Elutriation was performed using 20–25g of sediments in autoclaved seawater (1 W/ 1V) agitated overnight on a rotary table for 15 hours and centrifuged at 1500 RPM for 5 minutes at 22°C. Elutriates (supernatants) were collected using a micropipette and stored in Falcon tubes at 4°C for toxicity tests on larvae. Despite real technical potential and the ecological significance of the results, which could be relevant, the preliminary trials conducted with the mollusk Tridacna maxima (two trials), the pearl oyster Pinctada margaritifera (three trials), the fish Platax orbicularis , and wild coral larvae ( Porites rus ) were not satisfactory, due to poor results of spawning and difficulties in obtaining mature brood stock at the period of testing. Due to logistical constraints, not all 150 sites were tested with the four species. A rigorous selection was made based on initial assessments to focus on the most representative and impacted sites, including reference sites. Within Ifremer hatchery facilities, and for the oyster Saccostrea cucculata , the gametes were obtained by scarification, while exondation was applied to the sea urchin Tripneustes gratilla to induce gamete emission. Eggs of the sea cucumber Holothuria fuscogilva were obtained from the Tahiti Marine Products (TMP) hatchery via thermal shock. L. stylirostris shrimp larvae were provided at the 1–2 nauplii stage by the Technical Aquaculture Center of VAIA (Tahiti). Concentrations of eggs or larvae, depending on the species, were adjusted by successive filtration or dilution before immediate use (Supplementary Material SM2). For the biological test, freshly fertilized eggs of S. cucullata , T. gratilla , and H. fuscogilva species, and nauplii larvae of L. stylirostris species were immersed in different dilutions of sediment elutriate in untreated 25-well cell culture plates (Sterilin plastics, Thermo Fisher Scientific, UK). To balance statistical representativeness and visual comfort for counting, embryo/ larvae concentrations were adjusted to have 30 to 50 individuals/well depending on the species studied. Test plates containing elutriate solutions were kept at room temperature as the room, to ensure proper acclimatization and prevent larval disturbance. For testing, plates were incubated at 28°C in a Memmert climatic chamber. The culture setup was maintained over a predefined period for each species (Table 1 ), stopping larval development before the exogenous feeding stage to avoid bacterial contamination biases. Larval development was regularly monitored using an inverted optical microscope. The tests were all terminated by adding 20µl of 8% formaldehyde per well (# 0.15% final) for counting, when at least 80% of the larvae under control conditions reached the requested stage. Controls Copper sulfate (CuSO 4 ) was selected for positive control to monitor the larval batch quality following the AFNOR procedure (AFNOR 2009 ). A stock solution of CuSO 4 was prepared at 1 g/L, then diluted for tests concentrations ranging from 1 to 1000 µg/L. To ensure that there was no contamination of our solutions during the preparation phases of our sediment elutriates and test plate conditioning, a dilution range was maintained on four samples (from different sites. Toxicity was measured at five concentrations of elutriates as follows: 0-10-50-75-100% of undiluted elutriate). The tests were conducted on L. stylirostris and T. gratilla . For each species, the sites included a harbor (sites T53; T55), a reef area (sites T36; T77), a potentially toxic area (site T10), and a presumed healthy are (site T5). Observed significant variation in the percentage of anomalies in relation to sediment dilution, if any, confirmed the presence of a toxic compound in the sediments. To assess the quality of the seawater used during the experiments, a negative control made of filtered and autoclaved seawater was used. The test was considered valid when normal larval development reached 80% (Goulais et al., 2024 ). Test analysis Larval counting was performed using a Leica DMI3000B inverted microscope to determine the percentage of developmental anomalies. Anomalies included unfertilized eggs, those deceased at an early developmental stage, or malformations (Table 1 and Fig. 2 ). For Saccostrea Cucculata , and because of the size of the D shaped larvae, only unfertilized eggs, abnormal and deceased larvae were counted Data processing For the determination of the EC50 (Effective Concentration causing 50% undeveloped larvae), toxicity was measured at five to seven concentrations of copper sulfate with three replicates for each concentration. Predictive models were used to estimate EC50 across multiple species exposed to CuSO 4 . Dose-response curves were generated and the final EC50 was calculated. Data from larval counting were expressed as Net Percentage of Abnormal Larvae (NPAL) (Galgani et al., 2006 ) and normalized to 100%, based on control means. For field experiments, normalized data were mapped using Google Earth Pro 7.3.6 and QGIS 3.36.1 software. Toxicity thresholds were defined: low toxicity ( 75%, red). For dose-response modeling and EC50 estimations, concentration–response curves were fitted using three standard models commonly applied in ecotoxicology: The probit model (Finney, 1971 ), the Weibull model with fixed exponent 1.4 (W1.4) (Mount et al., 1997 ; US EPA, 2002 ), and the constrained logistic model (S2) derived from Duggleby (Duggleby, 1981 ; Norberg-King, 1993 ). For each model, the EC50 (the concentration causing 50% of the maximal effect) was determined by numerically solving the fitted equation f(x) = 0.5. Nonlinear regression was performed using the least squares method via the curve fit function from the SciPy library in Python (Harris et al., 2020 ; Virtanen et al., 2020 ) or using the "drc: Analysis of Dose-Response Curve" package in RStudio 4.3.3. Confidence intervals (95%) for EC50 estimates were computed using Monte Carlo simulation. For each simulated parameter set, EC50 was recalculated by solving f(x) = 0.5, and percentiles [2.5%, 97.5%] defined the interval. Statistical analyses were conducted using RStudio software (version 4.3.3). A statistical description of each site was performed with the following measurements: sample size (N), mean, and standard deviation (SD). All analyses were performed using non-parametric statistics due to non-Gaussian distributions of developmental anomalies. Comparisons were conducted using a Kruskal-Wallis test and Dunn's post-hoc test, with significance set at p < 0.05. Results Dose-response curves were established to assess the sensitivity of different species to increasing concentrations of copper sulfate ranging from 0 to 1000 µg/L (Supplementary Material SM3). All species responded to the presence of copper, although their response varied. The results showed characteristic sigmoidal curves for the 4 species, with the Weibull 1.4 model as the most precise in terms of confidence interval (Fig. 3 and SM4). The species were ranked from most to least sensitive to copper as follows: T. gratilla , S. cucculata, H. fuscogilva , and L. stylirostris , with EC50 values of 57.2 to 60.1( S. cucculata ), 53.4 to 55.5 ( T. Gratilia ), 60.5 to 62.6 ( H. fuscogilva ), and 105.5 to 108.4 ( L. stylirostris ), depending on the model (SM4). Despite multiple attempts, obtaining fertilized eggs was challenging, due to non-ideal spawning periods, tests conducted on S. cucullata revealed a normal larval development rate of 66% (Table 6) which is low in comparison to thresholds typically established in the literature (Goulais et al., 2024 ). This was attributed to difficulties in obtaining high-quality fertilized gametes after scarification, a common issue in biological testing with mollusks. This performance led to the exclusion of this test from the final comparison, although the EC value and toxicity of sediments were measured. For the other species studied, the normal larval development rate larvae in negative controls was 85%, 77% and 92% for T. gracilla, H. fuscogilva and L. stylirostris , repectively, allowing for the calculation of the EC50, although this rate was only 77.04% for H. fuscogilva . Because of the poor results in negative controls, the species Saccostrea cucculata was not further considered in the analysis of results and results from field experiment were indicative only. To confirm that changes in the percentage of anomalies during larval development was a consequence of sediment pollution (positive control), tests were also performed in the two species L. stylirostris larvae compared to T. gratilla larvae, using sediments extracts from sites of various types and expected pollution levels (Supplementary Material SM5). The results of dose-response curves after exposure to sediment elutriate samples revealed variability in the percentage of anomalies, depending on the sites/ sediments; with a decreasing percentage after dilution of sediment elutriates. A greater tolerance of L. stylirostris larvae compared to T. gratilla larvae for the same sites was also confirmed Then, since a Shapiro test (p-value < 0.05) indicated a non-normal distribution of the percentage of anomalies, non-parametric tests were used for further analysis. The correlation matrix reveals significant associations between the three species, notably between H. fuscogilva and L. stylirostris (correlation coefficient = 0.4504), and in a lesser extent, between T. gratilla and H. fuscogilva (correlation coefficient = 0.3097) and T. gratilla and L. stylirostris (correlation coefficient = 0.2926) (Fig. 4 ). The comparison of mean percentages of developmental anomalies between species was conducted across all sites for which results are common to the three species. The mean percentage of developmental anomaly of L. stylirostris zoea larvae exposed to sediment elutriates was 6.04% (± 24.0%). In comparison, H. fuscogilva mid-auricularia larvae exposed to sediment elutriate exhibited 63.7% (± 43.5%) developmental anomalies, while T. gratilla pluteus larvae exposed to sediment elutriate showed 68.5% (± 33.1%) developmental anomalies (Fig. 5 ). The mean larval anomaly percentages are significantly different between species (p < 2.2 E-16, Fig. 5 ). Dunn's post-hoc test results confirm these significant differences between each pair of species: between H. fuscogilva and L. stylirostris (adjusted p-value = 1.991565e-23), between H. fuscogilva and T. gratilla (adjusted p-value = 1.336765e-03), and between L. stylirostris and T. gratilla (adjusted p-value = 1.727153e-42). Measuring and mapping differences sensitivity between sites and species revealed variations in sediment toxicity among the the 3 species (Figs. 6 and 7 , Supplementary material 6). In total, 90 sediment samples were tested for toxicity on H. fuscogilva . 122 sediment samples were tested on T. gratilla , and 63 sediment samples for toxicity on L. stylirostris (Supplementary materials SM6) among all the tested sites, 38 were common to all 3 species. T. gratilla revealed that 40% (49 on 122) of sites had toxic sediments effects, whereas 35% (32 on /90) and only 1.6% (1 on 63) of sites had toxic sediments for H. fuscogilva and L. stylirostris respectively. Details of the most critical zones in Tahiti island are given on Fig. 6 and supplementary Material SM6. The Faratea zone (sites TF1 to TF10) appears relatively free of toxicity, although T. gratilla larvae exhibited increased sensitivity with 3 highly toxic sediments. The Phaeton Bay in Tahiti (sites T8 to T17) shows moderate toxicity, mainly affecting the two echinoderm species, H fuscogilva and T. gratilla. Similarly, the harbor of Papeete (T 48 to 59 and T 38) exhibits moderate toxicity, with lower sensitivity of L. stylirostris In Tahiti, areas with high toxicity also include the golf river mouth area of Atimaono (site T2), the Teva i Uta harbor (site T3), Titaaviri in Papeari (site T8), the river mouth Aoma in Toahotu (site T 17), the Taina’s marina in Punauia (site T 32 & 33) and Vaitepiha in Tautira (site T85) (see Supplementary materials SM 6). Results for Moorea and the Leeward islands (Huahine, Raiatea, Tahaa, Bora Bora) (Fig. 6 ) shows that Moorea, is the most affected by toxicity of sediments among the Society Islands, with high levels of developmental anomalies detected in Opunohu and Cook bays (sites T79 and T81) and in the Haapiti area (site T74). Affected zones were also the Lake Maeva in Huahine (site H13), for all three tested species. In addition to some urban areas (Vaitape in Bora Bora and North Raiatea), certain tourist areas in Bora Bora (sites B12 and B17) or in Raiatea (Motu Nao Nao, R15), were found with high toxicity of sediments, especially for sea urchins. Finally, in some reef sites (e.g. Tahaa, T5) high toxicity was measured for H. fuscogilva . Comparison of larval anomaly rates between all 38 sites with tests performed using the three species, indicated significant differences among sites for the composite toxicity (cumulated percentages, p-value = 1.169e-11). Analysis of the cumulative results of larval development tests for the three species reveals that sediments from seven sites induced a high rate of anomalies, with adjusted p-values showing significant differences compared to the reference site. Lake Maeva in Huahine (site H13, p = 0.047), Atimaono (site T2, p = 0.047), Titaaviri in Papeari (T8, p = 0.044), Haapiti Bay in Moorea (T74, p = 0.041), Opunohu Bay in Moorea (T79, p = 0.044), Cook Bay in Moorea (T81, p = 0.044), and Vaitepiha in Tautira (site T85, p = 0.050). The species T. gratilla and H. fuscogilva particularly contributed to the observed anomalies at these sites. Discussion Through the utilization of early developmental stages, known to be highly sensitive to pollutants (Xi et al., 2014). Toxicity tests were performed on sediment elutriates from 150 sites sampled around the Society Archipelago, French Polynesia, enabling the characterization of inter-species and inter-site differences. Establishing dose-response curves after exposure to copper sulfate (CuSO4) provided a positive control, validating the methodology used and confirming the effect of a reference pollutant to quantify the dose-response relationship, thereby eliminating the risks of experimental biases that could skew the results. The variability in response to CuSO4 among the three tested species underscores the importance of considering the specific sensitivity of each species in risk assessment. While T. gratilla exhibited a higher sensitivity to copper compared to H. fuscogilva and L. stylirostris , relative sensitivity may vary depending on the pollutants and species considered. Ecotoxicological studies on tropical species are often limited, but comparisons with existing data provide useful information. Studies on Macrobrachium rosenbergii , a freshwater species, estimated the LC50 for copper at 0.46 mg/L (Osunde et al., 2004 ). Similarly, for L. stylirostris , Goulais et al. ( 2024 ) showed a Cu EC50 of 119.1 µg/L, in the same range as our study (EC50 = 92.33 µg/L), confirming interspecific variability. For sea cucumbers, previous studies (Rakaj et al., 2021 ; Morroni et al., 2020 ) evaluated the sensitivity of the temperate species Holothuria tubulosa and Holothuria polii , with respective EC50s at 100–110 µg/L and up to 260 µg/L, respectively. Conversely, Goulais et al. ( 2024 ) measured an EC50 of 30.2 µg/L in the tropical species Holothuria whitmaei , lower than the result found in our study for H. fuscogilva (EC50 of 77.04 µg/L), demonstrating intra-genus sensitivity variation and emphasizing the importance of species-specific studies. For sea urchins, Paracentrotus lividus , a species extensively studied in ecotoxicology, has estimated EC50 values for copper ranging between 24.7 and 28.8 µg/L (Morroni et al., 2023), while Arbacia lixula (46–53 µg/L) exhibits varying sensitivities (Carreras et al., 2021 ). Goulais et al. ( 2024 ) also reported an EC50 of 33.1 µg/L for the tropical species T. gratilla , below the value measured in our experiment with the same species (EC50 = 85.18µg/L), suggesting possible variability due to experimental or environmental conditions, notably biotic factors (Blewett et al., 2024 ) and, in our case, the maturity of the spawners. Interestingly, species belonging to the same taxonomic phylum may exhibit similar sensitivities. Exposure of larvae to increasing amounts of sediment elutriates from the four sites T10, T55, T77 and TF5, using Tripneustes gratilla , and the four sites T10, T53, T55, and TF5 using Litopenaeus stylirostris ( Supplementary material SM5) confirmed that toxicity must be attributed to a toxic factor present in sediment samples, enabling site comparison and identifying pollutants in sediments. Moreover, the significant correlations measured between species in field studies confirmed common response patterns to toxic compounds in the sampled sediments, especially for H. fuscogilva and L. stylirostris , although response values may differ. The results indicate, however, that T. gratilla and H. fuscogilva exhibited lower larval survival than L. stylirostris , highlighting the increased sensitivity of echinoderms to single contaminants and environmental matrices from an applied perspective (Pagano et al., 2017 ; Morroni et al., 2023). This vulnerability is compounded by their wide distribution, meroplanktonic development, rapid response, and the high sensitivity of their planktonic larvae to various contaminants (Sugni et al., 2007 ). Sea urchins, in particular, play a key role in hard-bottom habitats by regulating plant community dynamics (Grosso et al., 2022 ). They are widely recognized as ideal bioindicators in marine ecotoxicological tests due to the sensitivity of their embryos to the deleterious effects of many contaminants (Pagano et al., 2017 ; Gambardella et al., 2021 ). Similarly, sea cucumbers play a crucial role in regulating organic matter dynamics and decomposition processes in marine sediments (Pensa et al., 2022 ; Grosso et al., 2023 ). However, despite their ecological importance, our understanding of their sensitivity to pollutants remains limited compared to sea urchins. The high sensitivity of T. gratilla and H. fuscogilva in our study could provide a differentiated and ecologically valuable response to pollution, offering potential for regular monitoring of sediment quality in French Polynesia and more broadly in tropical waters. The interspecific variation underscores the importance of a multi-species approach for a more comprehensive and accurate assessment of ecotoxicological risks, avoiding generalizations that may underestimate or overestimate environmental impacts on a given ecosystem. The variability in sensitivity among species may stem from several factors, including differences in species physiology, larval developmental stages, and mechanisms of tolerance to environmental stressors. A unique aspect of our study is that, unlike all other tested species, we retrieved larvae of L. stylirostris at the nauplii stage rather than as fertilized eggs. This stage is considered relatively advanced in larval development, which could favor the selection of individuals already more resistant to environmental stressors. Additionally, it is worth noting that the tests were performed during a short perods, decreasing sensitivity. Finally, L. stylirostris is an introduced species in the Polynesian environment, not naturally occurring. It is typically observed in aquaculture sites, where conditions may be more stressful than in its natural habitat, favoring natural selection in which only individuals most resistant to contaminants reproduce (Li et al., 2016 ). Furthermore, criteria used for toxicity tests, such as exposure durations and larval volume-surface ratio, may also influence the observed results. Feeding may significantly affect larval development and interact with contaminants. Therefore, experiments were performed until larvae began feeding. T. gratilla and H. fuscogilva had respective incubation times of 72 hours and 48 hours, while L. stylirostris had a shorter incubation time of only 40 hours, reducing exposure time, which may partly explain its relatively lower sensitivity in our study.) Results from field experiments indicated that observed toxicity was highly variable, ranging from − 23–100% abnormal larvae across sampled sites. The relative absence of toxicity observed in the Faratea zone was attributed to the lack of significant pollution sources onshore. While this area has been planned for a regional development project, aimed at developing aquaculture farming for species such as H. fuscogilva and L. stylirostris, this work provides a scientific and technical basis for ongoing monitoring to assess potential changes in toxicity. Ultimately, the variability in sediment toxicity across different Polynesian sites, as a consequence of local pollution sources and specific environmental conditions, highlights the need for continuous and detailed monitoring of marine sediments, as well as the importance of considering local characteristics for effective management of marine ecosystems. In the absence of toxicity assessment standards for the South Pacific, particularly French Polynesia, we believe our results will contribute to the development of standardized tests for more rational risk management related to contaminants from harbor activities, agriculture, riverine inputs, tourism, coastal discharges, harbor dredging sludges, and accidental impact monitoring. Ranking the toxicity results showed priority sites to consider for further experiments and monitoring. These sites include the Vaitepiha estuary in Tautira (T85), Titaaviri in Papeari (T8), Atimaono (T2), Opunohu Bay (T79), Cook Bay (T81), and Haapiti Bay in Moorea (T74), as well as the area around Lake Maeva in Huahine (H13). In absence of chemical analysis, poorly developed in French Polynesia, the potential causes of this contamination remains undetermined but agricultural and urban runoff, as well as industrial effluents are suggested. A study underway on trace metals in algae sampled around Tahiti island, may provide soon insights about the role of urbanization, riverine inputs, winds and rainfalls around the island (Yantouri, 2019 , Zubia, in preparation), while leaching of contaminants after the weathering of volcanic rocks and soil erosion may contributes to a large amounts of these metals, as a common scheme in coastal waters (Amado Filho et al., 2013 ). Other data on environmental quality are not on chemical pollutants, but bacterial contamination. The link with the toxicity of sediments is not demonstrated, but evidence of bacterial contamination (CSE, 2024) indicates the absence of water treatment in the various towns around the island, and the importance of run offs, that may explain ouputs of contaminants such as in the case of the river mouths of Vaitepiha (T85) or Hitimahana (T43) located at the East coast of Tahiti) where toxicity was high. We understand this study has limitations affecting test execution, and interpretation, emphasizing the need to develop more robust handling protocols to ensure the reliability of results in future studies. Attempts to include Tridacna maxima, Pinctada margaritifera , and Saccostrea cucculata , both representative from the Polynesian ecosystems, were hindered by problems of seasonality, highlighting the importance of conducting tests during optimal maturity periods of the broodstock. Vial’s border effects and excessive thermal exchanges of water and lab during tests that may be lethal to larvae has been critical for some species that are strict in their thermal preference during larval development ( H.fuscogilva, T Gracilla ). Additionally, determining the optimal test duration, and the larval developmental stages for the first ever use of H fuscogilva in toxicity testing was challenging during preliminary experiments. Moreover, not only the tests performed focused on the acute toxicity of sediments, without consideration to chronic toxicity, but representativity could be discussed more. While sediment contamination is considered conservative, sediment structure can vary depending on hydrodynamic conditions, and resuspended contaminated sediments can spread over a much larger area than sampled. Thus, mapping of point toxicity remains indicative, and predictions require closer measurements. Nevertheless, the results show significant potential for chemical toxicity measurements, monitoring of a source or effluent (Merrot et al., 2022 ), and for assessing long-term changes (Kim et al., 2020 ). Conclusion and perspectives The objective of this study was to highlight the toxicity of coastal marine sediments from the Society Islands. Contaminated sediments may affect benthic organisms, which live directly in contact with sediments, as well as necto-benthic species due to the potential release of contaminants into the water column. The results have significant implications for the environmental management of marine ecosystems in French Polynesia. The identification of specific sites with sediment toxicity allows for prioritizing areas for future monitoring and management measures. The variability in sensitivity among the studied species also underscores the need for a multi-species approach to achieve a more comprehensive assessment of environmental impacts. Toxicity tests have demonstrated that sediments from certain sites are harmful to the early developmental stages of tropical organisms. Among the studied species, H. fuscogilva has never been used for measuring sediment toxicity in natural environments. In addition to its marked sensitivity, this species presents logistical and biological advantages, making it a valuable bio indicator for monitoring chemical contamination in tropical ecosystems. This study provides a relevant protocol that could serve as a reference for future ecotoxicological assessments, development of standardized toxicity tests and further monitoring. Understanding whole sediment elutriates were used for toxicity tests without identifying specific contaminants present, this study establishes the scientific and technical basis for prioritizing sites where contaminants should be identified through analytical chemistry. Future studies should also assess the in vitro toxicity of major known chemicals used in French Polynesia (e.g., pesticides for agriculture and mosquito control), ensuring a more targeted approach to pollution management and mitigation. Declarations Acknowledgements This study was conducted as part of an agreement between the Research Delegation of French Polynesia and IFREMER (agreement 6518 MPR-REC, 2023-2024). We would like to thank all contributors, particularly the teams at IFREMER for their assistance and for providing oyster and sea urchin larvae, as well as Tahiti Marine products (TMP), the VAIA hatchery, and Moerani Lehartel for supplying sea cucumbers, shrimp, and clam larvae, respectively. We also thank David Lecchini (Criobe/CNRS/EPHE) for his logistical support in Bora Bora, as well as Polynésienne des Eaux for providing the boat. Funding Declaration This study was funded by the Research Delegation of French Polynesia, under agreement 6518 MPR-REC, 2023-2024. References AFNOR (2009). Bio-essai d’écotoxicité aquatique sur le développement embryo-larvaire des bivalves. NF T90 XP-283. Amado Filho, G. M., Andrade, L. R., Karez, C. S., & Farina, M. (2013). Brown algae as biomonitors of coastal contamination by metals. Environmental Research , 132, 345–361. Andrefouët, S., M. Adjeroud.(2019) French Polynesia. In: SHEPPARD, Charles (ed.), World Seas: an Environmental Evaluation (Second Edition)., Chapter 38, Online. Academic Press, 2019. p. 827–854. https://doi.org/10.1016/B978-0-08-100853-9.00039-7 Beiras, R., E. His, M. Seaman (1998). Effects of storage temperature and duration on toxicity of sediments assessed by Crassostrea gigas oyster embryo bioassay. Environmental Toxicology and Chemistry. 1998. Vol. 17, no. 10, p. 2100– 2105. DOI 10.1002/etc.5620171028 . Blewett, T., K. Ackerly, L. Schlenker, S. Martin, K. Nielsen (2024) Implications of biotic factors for toxicity testing in laboratory studies, Science of The Total Environment, 908, 168220, https://doi.org/10.1016/j.scitotenv.2023.168220. Bonaventura, R., F. Zito, L. Morroni, D. Pellegrini, F. Regoli, A. Pinsino (2021) Development and validation of new analytical methods using sea urchin embryo bioassay to evaluate dredged marine sediments. Journal of Environmental Management, 281, 111862, DOI 10 .1016/j.jenvman.2020.111862 . Boulanger, E., Barst, B.D., Alloy, M., Blais, S., Houde, M., Head, A. (2019) Assessment of environmentally contaminated sediment using a contact assay with early life stage zebrafish (Danio rerio). Science of The Total Environment. 659, 950–962. DOI 10.1016/j.scitotenv.2018.12.265 . Broccoli, A., L. Morroni, A. Valentini, V. Vitiello, M. Renzi, C. Nuccio, D. Pellegrini (2021) Comparison of different ecotoxicological batteries with WOE approach for the environmental quality evaluation of harbour sediments. Aquatic Toxicology, 237, 105905. DOI 10.1016/j.aquatox.2021.105905 . Carreras, C., V. Ordonez, A. Garcia-Cisneros, O. Wangensteen, C. Palacin, M. Pascual, X. Turon ( 2021). The Two Sides of the Mediterranean: Population Genomics of the Black Sea Urchin Arbacia lixula (Linnaeus, 1758) in a Warming Sea. Frontiers in Marine Science. Online. 2021. Vol. 8. DOI 10.3389/fmars.2021.739008 . CSE (Centre de Santé Environnementale)(2024). Qualité bactériologique des eaux de baignade. Ïles de Tahiti, Moorea, Bora Bora, Raiatea, Nuku Hiva, Hiva Oa et Tubuai. Campagne 2022-2023. Rapport. Centre de santé environnementale, Direction de la santé de la Polynésie française. 27 pp. Chen, C., C Ju, Y. Lim, Y. Wang, M.-H., Albarico, F. Paolo Jay B., C. Chen, C. Dong (2022). Potential sources and toxicity risks of polycyclic aromatic hydrocarbons in surface sediments of commercial ports in Taiwan. Marine Pollution Bulletin, Vol. 181, 113924, DOI 10.1016/j.marpolbul.2022.113924 . Crusot, M., T. Gardon, T. Richmond, R. Jezequel, E. Barbier, N. Gaertner-Mazouni (2024) Chemical toxicity of leachates from synthetic and natural-based spat collectors on the embryo-larval development of the pearl oyster, Pinctada margaritifera, Journal of Hazardous Materials, 479, 135647, https://doi.org/10.1016/j.jhazmat.2024.135647 Dang, D., N. Layglon, N. Ferretto, D. Omanovic, J. Mullot, V. Lenoble, V., S. Mounier, C. Garnier (2020) Kinetic processes of copper and lead remobilization during sediment resuspension of marine polluted sediments. Science of The Total Environment. 2020. Vol. 698, p. 134120.DOI 10.1016/j.scitotenv.2019.134120 . Duggleby, R.G. (1981) A nonlinear regression program for small computers. Anal Biochem. 1981 Jan 1;110(1):9-18. doi: 10.1016/0003-2697(81)90104-4. Finney, D. J. (1971). Probit Analysis (3rd ed.). Cambridge University Press, 333p., https://doi.org/10.1002/jps.2600600940 Galgani, F., JF. Chiffoleau, V. Orsoni, L. Costantini, Y. Bpoissery, S. Calendini, B. Andral (2006) Chemical contamination and sediment toxicity along the coast of Corsica. Chemistry and Ecology. 2006. Vol. 22, no. 4, 299–312, DOI 10.1080/02757540600812156 . Galgani, F., Y. Baldi (2010) Evaluation de la toxicité globale des sédiments du littoral du Languedoc Roussillon, du Var et des Alpes Maritimes par un bio essai : Développement larvaire de l’huître creuse Crassostrea gigas en présence d’élutriats de sédiments. Rapport IFREMER/ LER PAC00028, https://archimer.ifremer.fr/doc/00028/13930/ Gambardella, C., O. Leggio, A. Montarsolo, A. Harriague, A.0 Covazzi, M. Delcore, M. Faimali, F. Garaventa (2022). An integrated approach to characterize deep sediment toxicity in Genoa submarine canyons (NW Mediterranean). Environmental Science and Pollution Research. 2022. Vol. 29, no. 2, 2883–2893. DOI 10.1007/s11356 - 021 - 15807 - 0 . Gambardella, C., F. Marcellini, C. Falugi, S. Varrella, C. Corinaldesi (2021). Early-stage anomalies in the sea urchin (Paracentrotus lividus) as bioindicators of multiple stressors in the marine environment: Overview and future perspectives. Environmental Pollution, 287, 117608. DOI 10.1016/j.envpol.2021.117608 . Goulais, M., D. Saulnier, J.Rouxel, F. Galgani (2024). Bioindicator Species of Plastic Toxicity in Tropical Environments. Science of the Total Environment, 954, 176185, https://doi.org/10.1016/j.scitotenv.2024.176185 , Grosso, L., A. Rakaj, A. Fiancini, L. Tancioni (2022) Trophic Requirements of the Sea Urchin Paracentrotus lividus Varies at Different Life Stages: Comprehension of Species Ecology and Implications for Effective Feeding Formulations. Frontiers in Marine Sciences, vol 9, DOI: 10.3389/fmars.2022.865450 Grosso, L., M. Rampacci, D. Pensa, A. Fianchini, E. Batir, I Aydain, L. Ciriminna, P. Felix, A. Pombo, A. Lovatelli, S. Vizzini, M. Scardi, A. Rakaj (2023) Evaluating sea cucumbers as extractive species for benthic bioremediation in mussel farms. Scientific Reports. 2023. Vol. 13. DOI 10.1038/s41598 - 023 - 28733 - 7 . Hajji, A., Lucas, K. (2024) Anthropogenic stressors and the marine environment: From sources and impacts to solutions and mitigation, Marine Pollution Bulletin, 205, 116557,https://doi.org/10.1016/j.marpolbul.2024.116557. Harris, C. R., Millman, K. J., van der Walt, S. J., et al. (2020). Array programming with NumPy. Nature, 585(7825), 357–362. https://doi.org/10.1038/s41586-020-2649-2 Hama Aziz, K., F.S. Mustafa, K.M. Omer, S. Hama, R. Fayaq Hamarawf, K. Othman Rahma (2023) Heavy metal pollution in the aquatic environment: efficient and low-cost removal approaches to eliminate their toxicity: a review. RSC Adv. , 2023, 13, 17595-17610, https://pubs.rsc.org/en/content/articlehtml/2023/ra/d3ra00723e Hodge, A., F. Hopkins, M. Saha, A. Jha-(2025) Ecotoxicological effects of sunscreen derived organic and inorganic UV filters on marine organisms: A critical review, Marine Pollution Bulletin, 213, 117627,https://doi.org/10.1016/j.marpolbul.2025.117627. Kim, S., S. Hong, J. Lee, T. Kim, T. Yoon, J. Lee, K. Choi, B Kwon, J. Giesy, J. Khim (2020) Long-term trends of persistent toxic substances and potential toxicities in sediments along the west coast of South Korea. Marine Pollution Bulletin. 2020. Vol. 151, 110821. DOI 10.1016/j.marpolbul.2019.110821 . Leistenschneider, D., Wolinski, A., Cheng, J., Ter Halle, A., Duflos, G., Huvet, A., Paul-Pont; I, Lartaud, F., Galgani, F., Lavergne, E., Meistertzheim, A., Ghiglione, J.F., (2023). A critical review on the evaluation of toxicity and ecological risk assessment of plastics in the marine environment . Science of the Total Environment, 896, 164955 (15p.), https://doi.org/10.1016/j.scitotenv.2023.164955 , Li, W., X.Lu, S.Luan, K. Luo, J. Sui ; J. Kong (2016) Heritability of body weight and resistance to ammonia in the Pacific white shrimp Litopenaeus vannamei juveniles | Journal of Oceanology and Limnology.34, 1025-1033, https://link.springer.com/article/10.1007/s00343 - 016 - 5034 - 0 Merrot, P., F. Juillot, L. Flipo, M. Tharaud, E. Viollier, V. Noel, P. Le pape, J.M. Fernandez, B. Torreton, G. Morin (2022). Bioavailability of chromium, nickel, iron and manganese in relation to their speciation in coastal sediments downstream of ultramafic catchments: A case study in New Caledonia. Chemosphere. 302, 134643. DOI 10.1016/j.chemosphere.2022.134643 . Mkuye, R., C. Yang, F. Masanja, S. Ibrahim, X. Yang, H.Mwemi, P.Mrope, M.Salman, A.Alfatat, Y.Deng (2025) Omics insights in responses of bivalves exposed to plastic pollution, Aquatic Toxicology, 279, 107224, https://doi.org/10.1016/j.aquatox.2024.107224. Morroni, L., A. Rakaj, L. Grosso, A FIanchini, D. Pellegrini, F. Regoli (2020) Sea cucumber Holothuria polii (Delle Chiaje, 1823) as new model for embryo bioassays in ecotoxicological studies. Chemosphere. 2020. Vol. 240, p. 124819. DOI 10.1016/j.chemosphere.2019.124819 . Morroni, L., A. Rakaj, L. Grosso, A FIanchini, D. Pellegrini, F. Regoli (202). Echinoderm larvae as bioindicators for the assessment of marine pollution: Sea urchin and sea cucumber responsiveness and future perspectives. Environmental Pollution, 335, 122285. DOI 10.10 16/j.envpol.2023.122285 . Mount, D. R., Gulley, D. D., Hockett, J. R., Garrison, T. D., & Evans, J. M. (1997). Use of a Weibull model to estimate EC50s and confidence intervals in toxicological bioassays. Environmental Toxicology and Chemistry, 16(7), 1291–1294. https://doi.org/10.1002/etc.5620160706 Muller-Karanassos, C., W. Arundel, P. Lindeque, T. Vance, A. Turner, M. Cole (2021) Environmental concentrations of antifouling paint particles are toxic to sediment-dwelling invertebrates. Environmental Pollution, 268, 115754. DOI 10.1016/j.envpol.2020.115754 . Norberg-King, T. J. (1993). A linear interpolation model for estimating EC50s and IC50s. EPA Report 600/3-91/055. U.S. Environmental Protection Agency, Duluth, MN. Osunde, I., S. Coyle, J. Tidwell (2004) Acute Toxicity of Copper to Juvenile Freshwater Prawns, Macrobrachium rosenbergii : Journal of Applied Aquaculture, 14:3-4, 71-79, https://www.tandfonline.com/doi/abs/10.1300/J028v14n03_06 Pensa, D., A. Fianchini, L. Grosso, D. Ventura, S. Cataudella, M. Scardi, A Rekaj (2022) Population status, distribution and trophic implications of Pinna nobilis along the South-eastern Italian coast. Biodiversity. 2022. Vol. 1. DOI 10.1038/s44185 - 022 - 00002 - 2 . Pagano, G., M. Guida, M. Trifuoggi, P. Thomas, A. Palumbo, G. Romanov, R. Oral (2017) Sea Urchin Bioassays in Toxicity Testing: I. Inorganics, Organics, Complex Mixtures and Natural Products. Expert Opinion on Environmental Biology. Online. 2017. Vol. 06, no. 01, DOI 10.4172/2325 - 9655.1000142 . Rakaj, A., L. Morroni, L. Grosso, A. Fianchini, D. Pensa, D. Pellegrini, F Regoli (2021) Towards sea cucumbers as a new model in embryo-larval bioassays: Holothuria tubulosa as test species for the assessment of marine pollution. Science of The Total Environment, Vol. 787, p. 147593. DOI 10.1016/j.scitotenv.2021.147593 . Reguera, P., L. Couceiro, N. Fernandez (2018) A review of the empirical literature on the use of limpets Patella spp. (Mollusca: Gastropoda) as bioindicators of environmental quality. Ecotoxicology and Environmental Safety. 2018. Vol. 148, p. 593– 600. DOI 10.1016/j.ecoenv.2017.11.004 . Ritz, C., Baty, F., Streibig, J. C., & Gerhard, D. (2015). Dose–Response Analysis Using R. PLOS ONE, 10(12), e0146021. https://doi.org/10.1371/journal.pone.0146021 Ruocco, N. I. Bertocci, M. Munari, L. Musco, D. Caramiello, R. Danovaro, V. Zupo, M. Costantini (2020) Morphological and molecular responses of the sea urchin Paracentrotus lividus to highly contaminated marine sediments: The case study of Bagnoli-Coroglio brownfield (Mediterranean Sea). Marine Environmental Research. 154, 104865, DOI 10.1016/j.marenvres.2019.104865 . Salvat, B., H. Roche, P. Berny, F. Ramade (2012) Recherches sur la contamination par les pesticides d’organismes marins des réseaux trophiques récifaux de Polynésie française. Revue d’Écologie. 2012. Vol. 67, no. 2, p. 129– 147. Schiwy, S., M. Velki, H. Hollert (2020). Whole-Sediment Toxicity Bioassay to Determine Bioavailability and Effects of Aquatic Contaminants Using Zebrafish Embryos. In: Seiler, T.B., Brinkmann, M. (eds) In Situ Bioavailability and Toxicity of Organic Chemicals in Aquatic Systems. Methods in Pharmacology and Toxicology. Humana, New York, NY. https://doi.org/10.1007/7653_2020_42 Sciarrillo, R., D. Zuzolo, D. Cichella, F. Lannone, G. Camino, C. Guarino (2020) Contamination and ecological risk assessment of the seaport of Naples (Italy): Insights from marine sediments. Journal of Geochemical Exploration. 2020. Vol. 210, 106449. DOI 10.1016/j.gexplo.2019.106449 . Sugni, M., D. Mozzi, A. Barbaglio, F. Bonasoro, MD. Candia Carnevall (2007) Endocrine disrupting compounds and echinoderms: new ecotoxicological sentinels for the marine ecosystem. Ecotoxicology (London, England). 2007. Vol. 16, no. 1, p. 95–108. DOI 10.1007/s10646 - 006 - 0119 - 8 . USEPA (1993) Methods for Measuring the Acute Toxicity of Effluents and Receiving Waters to Freshwater and Marine Organisms, 4th edition, 273 pages, EPA-821-R-02-012. www3.epa.gov/npdes/pubs/atx.pdf US EPA (2002)- Short-Term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Marine and Estuarine Organisms. Fourth edition, 350p., EPA-821-R-02-014 Virtanen, P., Gommers, R., Oliphant, T. E., et al. (2020). SciPy 1.0: Fundamental Algorithms for Scientific Computing in Python. Nature Methods, 17, 261–272. https://doi.org/10.1038/s41592-019-0686-2 YANTOURI, S. (2019) Les algues polynésiennes : Quelles potentialités de valorisation au regard de leur teneurs en métaux toxiques ? Mémoire de stage de Master 2, Année universitaire: 2018-2019, Université de Bretagne Occidentale, 36 pp Additional Declarations No competing interests reported. Supplementary Files TIARESupplementarymaterialsfinalversion.docx Cite Share Download PDF Status: Posted Version 1 posted 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. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-6711214","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":466453499,"identity":"5a5d9bdc-6b5d-4718-ac78-37bf62c8ff90","order_by":0,"name":"Francois Galgani","email":"data:image/png;base64,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","orcid":"","institution":"French Research Institute for the Exploitation of the Sea IFREMER","correspondingAuthor":true,"prefix":"","firstName":"Francois","middleName":"","lastName":"Galgani","suffix":""},{"id":466453500,"identity":"fdc6921f-f0c8-4d86-a76e-5cb350529196","order_by":1,"name":"Maelys Jouet","email":"","orcid":"","institution":"French Research Institute for the Exploitation of the Sea IFREMER","correspondingAuthor":false,"prefix":"","firstName":"Maelys","middleName":"","lastName":"Jouet","suffix":""},{"id":466453501,"identity":"59fa2c26-44f1-4c1a-9b98-b7e2e3db3114","order_by":2,"name":"Maeva Goulais","email":"","orcid":"","institution":"French Research Institute for the Exploitation of the Sea IFREMER","correspondingAuthor":false,"prefix":"","firstName":"Maeva","middleName":"","lastName":"Goulais","suffix":""},{"id":466453502,"identity":"99e775cb-d6d5-4111-9152-af996ca2a563","order_by":3,"name":"Nono-lewis Tetaura","email":"","orcid":"","institution":"French Research Institute for the Exploitation of the Sea IFREMER","correspondingAuthor":false,"prefix":"","firstName":"Nono-lewis","middleName":"","lastName":"Tetaura","suffix":""},{"id":466453503,"identity":"b4a4df98-3d8c-4911-be6b-01f23e7add86","order_by":4,"name":"Alain Lo-Yat","email":"","orcid":"","institution":"French Research Institute for the Exploitation of the Sea IFREMER","correspondingAuthor":false,"prefix":"","firstName":"Alain","middleName":"","lastName":"Lo-Yat","suffix":""}],"badges":[],"createdAt":"2025-05-20 23:53:08","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6711214/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6711214/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":84019338,"identity":"a0487729-5a5b-4efd-a0e9-67ee7673b5f0","added_by":"auto","created_at":"2025-06-05 19:28:09","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1861897,"visible":true,"origin":"","legend":"\u003cp\u003eSee image above for figure legend\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6711214/v1/fd1c56d879a897a5e542f6f0.png"},{"id":84019540,"identity":"f27093bf-bc03-4eb2-a19a-52992c97e6f2","added_by":"auto","created_at":"2025-06-05 19:36:09","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1199342,"visible":true,"origin":"","legend":"\u003cp\u003eMain development stages and targeted stages for sediment toxicity testing using the oyster\u003cem\u003e Saccostrea cucullata\u003c/em\u003e (a), the sea cucumber \u003cem\u003eHolothuria fuscogilva\u003c/em\u003e (b), the shrimp \u003cem\u003eLitopenaeus stylirostris\u003c/em\u003e (c), and the sea urchin \u003cem\u003eTripneustes gratilla\u003c/em\u003e (d). Photographs of main critical stages encountered: normal D larvae (a.2), D larvae with mantle anomaly (a.3), shell anomaly (a.4), oocytes (a.5), mid-auricularia larvae, (b.2), early auricularia (b.3), malformed larvae (b.4), oocytes (b.5), zoea larvae (c.2), nauplii 5/6 larvae (c.3), nauplii 2/3 larvae (c.4), oocytes (c.5), pluteus larvae (d.2), early pluteus larvae (d.3), prism larvae (d.4), oocytes (d.5).\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6711214/v1/8d86995dabf8d08f1a9a305b.png"},{"id":84019539,"identity":"9a4e4ed0-66cb-4a6e-90d7-dac627c33f6b","added_by":"auto","created_at":"2025-06-05 19:36:09","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":520192,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eDose-response curves (abnormal larvae vs CUSO4 concentrations) fitted using the Weibull 1.4 model for EC50 estimations for the species S. cucculata, T. gratilla, H. fuscogilva, and L. stylirostris. See also Material and methods and supplementary materials SM2, SM3, and SM4 for experimental details and EC50 calculations for the 4 species using three different models\u003c/em\u003e\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6711214/v1/d0e1dee273e2b544cd84f52c.png"},{"id":84019882,"identity":"7d128bae-cdaf-4eef-826d-fcc91aeace36","added_by":"auto","created_at":"2025-06-05 19:44:09","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":568936,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eCorrelation matrix between the species Holothuria fuscogilva, Litopenaeus stylirostris, and Tripneustes gratilla. The species Saccostrea cucculata was no further considered in the analysis because of poor controls.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-6711214/v1/39f6db9310a30ddb4a0eb46a.png"},{"id":84019341,"identity":"f0dfde73-395a-48e4-a79a-b785cf622e18","added_by":"auto","created_at":"2025-06-05 19:28:09","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":215526,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eComparison of mean percentages and 95% confidence intervals (bars) of developmental anomalies across species. (**) and (***) indicate the degree of significance (see associated text for details)\u003c/em\u003e\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-6711214/v1/0fc763d1a4970be53dda890c.png"},{"id":84019544,"identity":"11faf3e1-ca17-464c-abdd-7990761ce52b","added_by":"auto","created_at":"2025-06-05 19:36:09","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":1119518,"visible":true,"origin":"","legend":"\u003cp\u003eSee image above for figure legend\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-6711214/v1/91f73f2346afbda5849bba49.png"},{"id":84019352,"identity":"cf01b68a-660a-437e-81bd-3d8f1a88b617","added_by":"auto","created_at":"2025-06-05 19:28:09","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":1202359,"visible":true,"origin":"","legend":"\u003cp\u003eSee image above for figure legend\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-6711214/v1/3f8026fbf685f790b0ce83a7.png"},{"id":86164176,"identity":"1b03626e-82a8-4793-8a24-1c0934cc5b94","added_by":"auto","created_at":"2025-07-07 13:09:01","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":8809476,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6711214/v1/9f1bc722-c624-4180-8afe-555c36bda553.pdf"},{"id":84019538,"identity":"2bf51690-8f80-4ba2-9bf0-1331b6f60a7a","added_by":"auto","created_at":"2025-06-05 19:36:09","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":196964,"visible":true,"origin":"","legend":"","description":"","filename":"TIARESupplementarymaterialsfinalversion.docx","url":"https://assets-eu.researchsquare.com/files/rs-6711214/v1/d12e9424deb2e62b7413b914.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eAssessment of Sediment Quality and Vulnerability of Tropical Marine Species in the Society Islands, French Polynesia\u003c/p\u003e","fulltext":[{"header":"Highlights","content":"\u003cul\u003e\n \u003cli\u003eThe first large-scale use of toxicity tests to map sediment quality in French Polynesia. \u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/li\u003e\n \u003cli\u003eThe first use ever of the white sea cucumber species (\u003cem\u003eHolothuria fuscogilva\u003c/em\u003e) for toxicity tests.\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/li\u003e\n \u003cli\u003eThe study highlights sediment toxicity in certain polluted sites of the Society Archipelago. \u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/li\u003e\n \u003cli\u003eThe echinoderms \u003cem\u003eHolothuria fuscogilva\u0026nbsp;\u003c/em\u003eand \u003cem\u003eTripneustes gratilla\u0026nbsp;\u003c/em\u003ewere the most sensitive.\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/li\u003e\n\u003c/ul\u003e\n"},{"header":"Introduction","content":"\u003cp\u003eAquatic ecosystems worldwide are increasingly threatened by the accumulation of anthropogenic pollutants stemming from industrial, urban, and agricultural activities. These contaminants pose significant risks to environmental and human health due to their persistence and potentially harmful effects on aquatic organisms and ecosystems (review in Hadji \u0026amp; Lucas, 2024). Sediments, acting as natural sinks for pollutants in aquatic environments, play a crucial role in the accumulation and storage of contaminants over time, also acting as reservoirs for various toxic compounds like heavy metals, organic pollutants, and microplastics (Ruocco et al., \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2020\u003c/span\u003e ; Gambardella et al., \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2021\u003c/span\u003e ; Leistenschneider et al., \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2023\u003c/span\u003e ; Hama Aziz et al., \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Furthermore, resuspension of contaminated sediments by storms or dredging operations can increase the bioavailability of contaminated particles. This process contributes to the accumulation of toxic substances and can engender long-term effects on sediment-associated living communities (Schiwy et al., 2022).\u003c/p\u003e \u003cp\u003eWhile the assessment of sediment quality has become imperative for many countries where human activities are intense (Boulanger et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2019\u003c/span\u003e), ecotoxicology is key for understanding the impacts of pollutants on aquatic environments, offering multidisciplinary approaches to assess ecological risks of contaminated sediments (Gambardella et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Standardized toxicity tests and biological assays are commonly used to evaluate sediment quality and the potential toxic effects of pollutants on aquatic organisms (Bonaventura et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Broccoli et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) with larvae of bivalves, echinoderms and decapods often used due to their sensitivity (Reguera et al., \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Gambardella et al., \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn recent years, significant advancements have been made in ecotoxicology, including the study of particle and plastic toxicity (Leistenschneider et al., \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) and emergent contaminants (Hodge et al., \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2025\u003c/span\u003e), and the integration of molecular biology techniques (metabolomics, mutagenesis, environmental DNA) (Mkuye et al., \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). However, despite these advancements, there is a lack of specific investigations in certain regions, such as French Polynesia where the use of toxicity test has been limited to plastic pollution (Goulais et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Cruzot et al., 2024). This tropical region is characterized by seasonal climatic conditions, temperature and precipitation variations, and geographical specificities like the dispersion of islands and extensive coral reefs (Andr\u0026eacute;fou\u0026euml;t \u0026amp; Adjeroud, 2019), which can influence the distribution and impact of contaminants in sediments. This study aims to evaluate the potential toxicity of contaminated marine sediments in French Polynesia using bioassays, enumerating anomalies occurring during the larval development of benthic marine species exposed to sediment elutriates from the Society Islands. The results of four bioassays are compared to evaluate local environmental risks, providing early warning indicators to locate contamination risk areas. Among the selected toxicity tests, larval development tests of the oyster (\u003cem\u003eSaccostrea cucullata\u003c/em\u003e), holothurian (\u003cem\u003eHolothuria whitmaei\u003c/em\u003e), sea urchin (\u003cem\u003eTripneustes gratilla\u003c/em\u003e), and shrimp (\u003cem\u003eLitopenaeus stylirostris\u003c/em\u003e) were chosen to study the quality of sediment elutriates. These analyses will help formulate testable hypotheses on the causes of sediment pollution in French Polynesia, develop monitoring methodologies, and guide further research to identify the nature of contamination.\u003c/p\u003e"},{"header":"Materials et Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eSampling\u003c/h2\u003e \u003cp\u003eThe study covered 150 sites distributed across six islands of the Society archipelago in French Polynesia, South Pacific. Sampling sites included the islands of Tahiti (n\u0026thinsp;=\u0026thinsp;80), Moorea (n\u0026thinsp;=\u0026thinsp;15), Huahine (n\u0026thinsp;=\u0026thinsp;13), Bora Bora (n\u0026thinsp;=\u0026thinsp;16), Raiatea (n\u0026thinsp;=\u0026thinsp;17), and Taha'a (n\u0026thinsp;=\u0026thinsp;9) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and Supplementary Material SM 1). Sites were selected to represent varying contamination levels, covering diverse areas impacted by various anthropogenic activities, including harbors, tourist areas, river mouths, aquacultutre zones, and reef structures. The maximum depth ranged from a few centimeters to 40 m (Faratea, Tahiti) (Supplementary Material SM 1).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSediment samples were collected between 0.5 cm and 40m depth, over a period of three weeks, from 10/01/2024 to 26/01/2024. Approximately 100g of the top 3 centimeters of sediment were collected using polypropylene tubes and Van veen grab depending on the depth, and preserved in 50ml Falcon tubes. Surface sediments were double-sampled at each site to account for potential loss and more representativeness. Once collected, sediment samples were stored in a refrigerated cooler with ice and transported to the laboratory where they were stored at 4\u0026deg;C for a maximum of three weeks before being used for elutriate preparation, as polluted sediments may maintain their toxicity for over four weeks (Beiras et al., 2009). Spatial coordinates of each sampled site were recorded using GPSMAP 78 for a precise mapping of the study results.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eLarval development test\u003c/h3\u003e\n\u003cp\u003eThe seawater used for all experiments, pumped from the Vairao lagoon (Tahiti, French Polynesia), was filtered (25\u0026micro;m, 5\u0026micro;m, and 1\u0026micro;m), treated by UVs, autoclaved, and the stability of water salinity was checked. The sediment extraction step was adapted from the protocol used by Galgani \u0026amp; Baldi. (2010), derived from AFNOR T90 XP-283 (2009), updated in 2015 (ISO standard procedure 17244:2015, under review). Elutriation was performed using 20\u0026ndash;25g of sediments in autoclaved seawater (1 W/ 1V) agitated overnight on a rotary table for 15 hours and centrifuged at 1500 RPM for 5 minutes at 22\u0026deg;C. Elutriates (supernatants) were collected using a micropipette and stored in Falcon tubes at 4\u0026deg;C for toxicity tests on larvae.\u003c/p\u003e \u003cp\u003eDespite real technical potential and the ecological significance of the results, which could be relevant, the preliminary trials conducted with the mollusk \u003cem\u003eTridacna maxima\u003c/em\u003e (two trials), the pearl oyster \u003cem\u003ePinctada margaritifera\u003c/em\u003e (three trials), the fish \u003cem\u003ePlatax orbicularis\u003c/em\u003e, and wild coral larvae (\u003cem\u003ePorites rus\u003c/em\u003e) were not satisfactory, due to poor results of spawning and difficulties in obtaining mature brood stock at the period of testing.\u003c/p\u003e \u003cp\u003eDue to logistical constraints, not all 150 sites were tested with the four species. A rigorous selection was made based on initial assessments to focus on the most representative and impacted sites, including reference sites.\u003c/p\u003e \u003cp\u003eWithin Ifremer hatchery facilities, and for the oyster \u003cem\u003eSaccostrea cucculata\u003c/em\u003e, the gametes were obtained by scarification, while exondation was applied to the sea urchin \u003cem\u003eTripneustes gratilla\u003c/em\u003e to induce gamete emission. Eggs of the sea cucumber \u003cem\u003eHolothuria fuscogilva\u003c/em\u003e were obtained from the Tahiti Marine Products (TMP) hatchery via thermal shock. \u003cem\u003eL. stylirostris\u003c/em\u003e shrimp larvae were provided at the 1\u0026ndash;2 nauplii stage by the Technical Aquaculture Center of VAIA (Tahiti). Concentrations of eggs or larvae, depending on the species, were adjusted by successive filtration or dilution before immediate use (Supplementary Material SM2).\u003c/p\u003e \u003cp\u003eFor the biological test, freshly fertilized eggs of \u003cem\u003eS. cucullata\u003c/em\u003e, \u003cem\u003eT. gratilla\u003c/em\u003e, and \u003cem\u003eH. fuscogilva\u003c/em\u003e species, and nauplii larvae of \u003cem\u003eL. stylirostris\u003c/em\u003e species were immersed in different dilutions of sediment elutriate in untreated 25-well cell culture plates (Sterilin plastics, Thermo Fisher Scientific, UK). To balance statistical representativeness and visual comfort for counting, embryo/ larvae concentrations were adjusted to have 30 to 50 individuals/well depending on the species studied. Test plates containing elutriate solutions were kept at room temperature as the room, to ensure proper acclimatization and prevent larval disturbance. For testing, plates were incubated at 28\u0026deg;C in a Memmert climatic chamber. The culture setup was maintained over a predefined period for each species (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), stopping larval development before the exogenous feeding stage to avoid bacterial contamination biases. Larval development was regularly monitored using an inverted optical microscope. The tests were all terminated by adding 20\u0026micro;l of 8% formaldehyde per well (# 0.15% final) for counting, when at least 80% of the larvae under control conditions reached the requested stage.\u003c/p\u003e\u003cp\u003e\u003cimg src=\"https://myfiles.space/user_files/122228_c8a1650c59388082/122228_custom_files/img1749145668.png\"\u003e\u003cbr\u003e\u003c/p\u003e\n\u003ch3\u003eControls\u003c/h3\u003e\n\u003cp\u003eCopper sulfate (CuSO\u003csub\u003e4\u003c/sub\u003e) was selected for positive control to monitor the larval batch quality following the AFNOR procedure (AFNOR \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). A stock solution of CuSO\u003csub\u003e4\u003c/sub\u003e was prepared at 1 g/L, then diluted for tests concentrations ranging from 1 to 1000 \u0026micro;g/L. To ensure that there was no contamination of our solutions during the preparation phases of our sediment elutriates and test plate conditioning, a dilution range was maintained on four samples (from different sites. Toxicity was measured at five concentrations of elutriates as follows: 0-10-50-75-100% of undiluted elutriate). The tests were conducted on \u003cem\u003eL. stylirostris\u003c/em\u003e and \u003cem\u003eT. gratilla\u003c/em\u003e. For each species, the sites included a harbor (sites T53; T55), a reef area (sites T36; T77), a potentially toxic area (site T10), and a presumed healthy are (site T5). Observed significant variation in the percentage of anomalies in relation to sediment dilution, if any, confirmed the presence of a toxic compound in the sediments. To assess the quality of the seawater used during the experiments, a negative control made of filtered and autoclaved seawater was used. The test was considered valid when normal larval development reached 80% (Goulais et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2024\u003c/span\u003e).\u003c/p\u003e\n\u003ch3\u003eTest analysis\u003c/h3\u003e\n\u003cp\u003eLarval counting was performed using a Leica DMI3000B inverted microscope to determine the percentage of developmental anomalies. Anomalies included unfertilized eggs, those deceased at an early developmental stage, or malformations (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). For \u003cem\u003eSaccostrea Cucculata\u003c/em\u003e, and because of the size of the D shaped larvae, only unfertilized eggs, abnormal and deceased larvae were counted\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eData processing\u003c/h3\u003e\n\u003cp\u003eFor the determination of the EC50 (Effective Concentration causing 50% undeveloped larvae), toxicity was measured at five to seven concentrations of copper sulfate with three replicates for each concentration. Predictive models were used to estimate EC50 across multiple species exposed to CuSO\u003csub\u003e4\u003c/sub\u003e. Dose-response curves were generated and the final EC50 was calculated. Data from larval counting were expressed as Net Percentage of Abnormal Larvae (NPAL) (Galgani et al., \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2006\u003c/span\u003e) and normalized to 100%, based on control means. For field experiments, normalized data were mapped using Google Earth Pro 7.3.6 and QGIS 3.36.1 software. Toxicity thresholds were defined: low toxicity (\u0026lt;\u0026thinsp;50% anomalies, green), moderate toxicity (50% -75%, yellow), and high toxicity (\u0026gt;\u0026thinsp;75%, red).\u003c/p\u003e \u003cp\u003eFor dose-response modeling and EC50 estimations, concentration\u0026ndash;response curves were fitted using three standard models commonly applied in ecotoxicology: The probit model (Finney, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e1971\u003c/span\u003e), the Weibull model with fixed exponent 1.4 (W1.4) (Mount et al., \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e1997\u003c/span\u003e ; US EPA, \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2002\u003c/span\u003e), and the constrained logistic model (S2) derived from Duggleby (Duggleby, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e1981\u003c/span\u003e; Norberg-King, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e1993\u003c/span\u003e). For each model, the EC50 (the concentration causing 50% of the maximal effect) was determined by numerically solving the fitted equation f(x)\u0026thinsp;=\u0026thinsp;0.5. Nonlinear regression was performed using the least squares method via the curve fit function from the SciPy library in Python (Harris et al., \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2020\u003c/span\u003e ; Virtanen et al., \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) or using the \"drc: Analysis of Dose-Response Curve\" package in RStudio 4.3.3. Confidence intervals (95%) for EC50 estimates were computed using Monte Carlo simulation. For each simulated parameter set, EC50 was recalculated by solving f(x)\u0026thinsp;=\u0026thinsp;0.5, and percentiles [2.5%, 97.5%] defined the interval.\u003c/p\u003e \u003cp\u003eStatistical analyses were conducted using RStudio software (version 4.3.3). A statistical description of each site was performed with the following measurements: sample size (N), mean, and standard deviation (SD). All analyses were performed using non-parametric statistics due to non-Gaussian distributions of developmental anomalies. Comparisons were conducted using a Kruskal-Wallis test and Dunn's post-hoc test, with significance set at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eDose-response curves were established to assess the sensitivity of different species to increasing concentrations of copper sulfate ranging from 0 to 1000 \u0026micro;g/L (Supplementary Material SM3). All species responded to the presence of copper, although their response varied. The results showed characteristic sigmoidal curves for the 4 species, with the Weibull 1.4 model as the most precise in terms of confidence interval (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e and SM4). The species were ranked from most to least sensitive to copper as follows: \u003cem\u003eT. gratilla\u003c/em\u003e, S. \u003cem\u003ecucculata, H. fuscogilva\u003c/em\u003e, and \u003cem\u003eL. stylirostris\u003c/em\u003e, with EC50 values of 57.2 to 60.1(\u003cem\u003eS. cucculata\u003c/em\u003e), 53.4 to 55.5 (\u003cem\u003eT. Gratilia\u003c/em\u003e), 60.5 to 62.6 (\u003cem\u003eH. fuscogilva\u003c/em\u003e), and 105.5 to 108.4 (\u003cem\u003eL. stylirostris\u003c/em\u003e), depending on the model (SM4).\u003c/p\u003e \u003cp\u003eDespite multiple attempts, obtaining fertilized eggs was challenging, due to non-ideal spawning periods, tests conducted on \u003cem\u003eS. cucullata\u003c/em\u003e revealed a normal larval development rate of 66% (Table\u0026nbsp;6) which is low in comparison to thresholds typically established in the literature (Goulais et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). This was attributed to difficulties in obtaining high-quality fertilized gametes after scarification, a common issue in biological testing with mollusks. This performance led to the exclusion of this test from the final comparison, although the EC value and toxicity of sediments were measured. For the other species studied, the normal larval development rate larvae in negative controls was 85%, 77% and 92% for \u003cem\u003eT. gracilla, H. fuscogilva\u003c/em\u003e and \u003cem\u003eL. stylirostris\u003c/em\u003e, repectively, allowing for the calculation of the EC50, although this rate was only 77.04% for \u003cem\u003eH. fuscogilva\u003c/em\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eBecause of the poor results in negative controls, the species \u003cem\u003eSaccostrea cucculata\u003c/em\u003e was not further considered in the analysis of results and results from field experiment were indicative only.\u003c/p\u003e \u003cp\u003eTo confirm that changes in the percentage of anomalies during larval development was a consequence of sediment pollution (positive control), tests were also performed in the two species \u003cem\u003eL. stylirostris\u003c/em\u003e larvae compared to \u003cem\u003eT. gratilla\u003c/em\u003e larvae, using sediments extracts from sites of various types and expected pollution levels (Supplementary Material SM5).\u003c/p\u003e \u003cp\u003eThe results of dose-response curves after exposure to sediment elutriate samples revealed variability in the percentage of anomalies, depending on the sites/ sediments; with a decreasing percentage after dilution of sediment elutriates. A greater tolerance of \u003cem\u003eL. stylirostris\u003c/em\u003e larvae compared to \u003cem\u003eT. gratilla\u003c/em\u003e larvae for the same sites was also confirmed Then, since a Shapiro test (p-value\u0026thinsp;\u0026lt;\u0026thinsp;0.05) indicated a non-normal distribution of the percentage of anomalies, non-parametric tests were used for further analysis. The correlation matrix reveals significant associations between the three species, notably between \u003cem\u003eH. fuscogilva\u003c/em\u003e and \u003cem\u003eL. stylirostris\u003c/em\u003e (correlation coefficient\u0026thinsp;=\u0026thinsp;0.4504), and in a lesser extent, between \u003cem\u003eT. gratilla\u003c/em\u003e and \u003cem\u003eH. fuscogilva\u003c/em\u003e (correlation coefficient\u0026thinsp;=\u0026thinsp;0.3097) and \u003cem\u003eT. gratilla\u003c/em\u003e and \u003cem\u003eL. stylirostris\u003c/em\u003e (correlation coefficient\u0026thinsp;=\u0026thinsp;0.2926) (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe comparison of mean percentages of developmental anomalies between species was conducted across all sites for which results are common to the three species. The mean percentage of developmental anomaly of \u003cem\u003eL. stylirostris\u003c/em\u003e zoea larvae exposed to sediment elutriates was 6.04% (\u0026plusmn;\u0026thinsp;24.0%). In comparison, \u003cem\u003eH. fuscogilva\u003c/em\u003e mid-auricularia larvae exposed to sediment elutriate exhibited 63.7% (\u0026plusmn;\u0026thinsp;43.5%) developmental anomalies, while \u003cem\u003eT. gratilla\u003c/em\u003e pluteus larvae exposed to sediment elutriate showed 68.5% (\u0026plusmn;\u0026thinsp;33.1%) developmental anomalies (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe mean larval anomaly percentages are significantly different between species (p\u0026thinsp;\u0026lt;\u0026thinsp;2.2 E-16, Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). Dunn's post-hoc test results confirm these significant differences between each pair of species: between \u003cem\u003eH. fuscogilva\u003c/em\u003e and \u003cem\u003eL. stylirostris\u003c/em\u003e (adjusted p-value\u0026thinsp;=\u0026thinsp;1.991565e-23), between \u003cem\u003eH. fuscogilva\u003c/em\u003e and \u003cem\u003eT. gratilla\u003c/em\u003e (adjusted p-value\u0026thinsp;=\u0026thinsp;1.336765e-03), and between \u003cem\u003eL. stylirostris\u003c/em\u003e and \u003cem\u003eT. gratilla\u003c/em\u003e (adjusted p-value\u0026thinsp;=\u0026thinsp;1.727153e-42).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eMeasuring and mapping differences sensitivity between sites and species revealed variations in sediment toxicity among the the 3 species (Figs.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e and \u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e, Supplementary material 6). In total, 90 sediment samples were tested for toxicity on \u003cem\u003eH. fuscogilva\u003c/em\u003e. 122 sediment samples were tested on \u003cem\u003eT. gratilla\u003c/em\u003e, and 63 sediment samples for toxicity \u003cem\u003eon L. stylirostris (Supplementary materials SM6)\u003c/em\u003e among all the tested sites, 38 were common to all 3 species. \u003cem\u003eT. gratilla\u003c/em\u003e revealed that 40% (49 on 122) of sites had toxic sediments effects, whereas 35% (32 on /90) and only 1.6% (1 on 63) of sites had toxic sediments for \u003cem\u003eH. fuscogilva\u003c/em\u003e and \u003cem\u003eL. stylirostris\u003c/em\u003e respectively.\u003c/p\u003e \u003cp\u003eDetails of the most critical zones in Tahiti island are given on Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e and supplementary Material SM6. The Faratea zone (sites TF1 to TF10) appears relatively free of toxicity, although \u003cem\u003eT. gratilla\u003c/em\u003e larvae exhibited increased sensitivity with 3 highly toxic sediments. The Phaeton Bay in Tahiti (sites T8 to T17) shows moderate toxicity, mainly affecting the two echinoderm species, H \u003cem\u003efuscogilva\u003c/em\u003e and \u003cem\u003eT. gratilla.\u003c/em\u003e Similarly, the harbor of Papeete (T 48 to 59 and T 38) exhibits moderate toxicity, with lower sensitivity of \u003cem\u003eL. stylirostris\u003c/em\u003e\u003cp\u003eIn Tahiti, areas with high toxicity also include the golf river mouth area of Atimaono (site T2), the Teva i Uta harbor (site T3), Titaaviri in Papeari (site T8), the river mouth Aoma in Toahotu (site T 17), the Taina\u0026rsquo;s marina in Punauia (site T 32 \u0026amp; 33) and Vaitepiha in Tautira (site T85) (see Supplementary materials SM 6).\u003c/p\u003e\n\n \u003cp\u003eResults for Moorea and the Leeward islands (Huahine, Raiatea, Tahaa, Bora Bora) (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e) shows that Moorea, is the most affected by toxicity of sediments among the Society Islands, with high levels of developmental anomalies detected in Opunohu and Cook bays (sites T79 and T81) and in the Haapiti area (site T74). Affected zones were also the Lake Maeva in Huahine (site H13), for all three tested species. In addition to some urban areas (Vaitape in Bora Bora and North Raiatea), certain tourist areas in Bora Bora (sites B12 and B17) or in Raiatea (Motu Nao Nao, R15), were found with high toxicity of sediments, especially for sea urchins. Finally, in some reef sites (e.g. Tahaa, T5) high toxicity was measured for \u003cem\u003eH. fuscogilva\u003c/em\u003e.\u003c/p\u003e \u003cp\u003eComparison of larval anomaly rates between all 38 sites with tests performed using the three species, indicated significant differences among sites for the composite toxicity (cumulated percentages, p-value\u0026thinsp;=\u0026thinsp;1.169e-11). Analysis of the cumulative results of larval development tests for the three species reveals that sediments from seven sites induced a high rate of anomalies, with adjusted p-values showing significant differences compared to the reference site. Lake Maeva in Huahine (site H13, p\u0026thinsp;=\u0026thinsp;0.047), Atimaono (site T2, p\u0026thinsp;=\u0026thinsp;0.047), Titaaviri in Papeari (T8, p\u0026thinsp;=\u0026thinsp;0.044), Haapiti Bay in Moorea (T74, p\u0026thinsp;=\u0026thinsp;0.041), Opunohu Bay in Moorea (T79, p\u0026thinsp;=\u0026thinsp;0.044), Cook Bay in Moorea (T81, p\u0026thinsp;=\u0026thinsp;0.044), and Vaitepiha in Tautira (site T85, p\u0026thinsp;=\u0026thinsp;0.050). The species \u003cem\u003eT. gratilla\u003c/em\u003e and \u003cem\u003eH. fuscogilva\u003c/em\u003e particularly contributed to the observed anomalies at these sites.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThrough the utilization of early developmental stages, known to be highly sensitive to pollutants (Xi et al., 2014). Toxicity tests were performed on sediment elutriates from 150 sites sampled around the Society Archipelago, French Polynesia, enabling the characterization of inter-species and inter-site differences.\u003c/p\u003e \u003cp\u003eEstablishing dose-response curves after exposure to copper sulfate (CuSO4) provided a positive control, validating the methodology used and confirming the effect of a reference pollutant to quantify the dose-response relationship, thereby eliminating the risks of experimental biases that could skew the results. The variability in response to CuSO4 among the three tested species underscores the importance of considering the specific sensitivity of each species in risk assessment.\u003c/p\u003e \u003cp\u003eWhile \u003cem\u003eT. gratilla\u003c/em\u003e exhibited a higher sensitivity to copper compared to \u003cem\u003eH. fuscogilva\u003c/em\u003e and \u003cem\u003eL. stylirostris\u003c/em\u003e, relative sensitivity may vary depending on the pollutants and species considered. Ecotoxicological studies on tropical species are often limited, but comparisons with existing data provide useful information. Studies on \u003cem\u003eMacrobrachium rosenbergii\u003c/em\u003e, a freshwater species, estimated the LC50 for copper at 0.46 mg/L (Osunde et al., \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2004\u003c/span\u003e). Similarly, for \u003cem\u003eL. stylirostris\u003c/em\u003e, Goulais et al. (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) showed a Cu EC50 of 119.1 µg/L, in the same range as our study (EC50 = 92.33 µg/L), confirming interspecific variability. For sea cucumbers, previous studies (Rakaj et al., \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Morroni et al., \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) evaluated the sensitivity of the temperate species \u003cem\u003eHolothuria tubulosa\u003c/em\u003e and \u003cem\u003eHolothuria polii\u003c/em\u003e, with respective EC50s at 100–110 µg/L and up to 260 µg/L, respectively. Conversely, Goulais et al. (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) measured an EC50 of 30.2 µg/L in the tropical species \u003cem\u003eHolothuria whitmaei\u003c/em\u003e, lower than the result found in our study for \u003cem\u003eH. fuscogilva\u003c/em\u003e (EC50 of 77.04 µg/L), demonstrating intra-genus sensitivity variation and emphasizing the importance of species-specific studies.\u003c/p\u003e \u003cp\u003eFor sea urchins, \u003cem\u003eParacentrotus lividus\u003c/em\u003e, a species extensively studied in ecotoxicology, has estimated EC50 values for copper ranging between 24.7 and 28.8 µg/L (Morroni et al., 2023), while \u003cem\u003eArbacia lixula\u003c/em\u003e (46–53 µg/L) exhibits varying sensitivities (Carreras et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Goulais et al. (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) also reported an EC50 of 33.1 µg/L for the tropical species \u003cem\u003eT. gratilla\u003c/em\u003e, below the value measured in our experiment with the same species (EC50 = 85.18µg/L), suggesting possible variability due to experimental or environmental conditions, notably biotic factors (Blewett et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) and, in our case, the maturity of the spawners. Interestingly, species belonging to the same taxonomic phylum may exhibit similar sensitivities.\u003c/p\u003e \u003cp\u003eExposure of larvae to increasing amounts of sediment elutriates from the four sites T10, T55, T77 and TF5, using \u003cem\u003eTripneustes gratilla\u003c/em\u003e, and the four sites T10, T53, T55, and TF5 using \u003cem\u003eLitopenaeus stylirostris\u003c/em\u003e ( Supplementary material SM5) confirmed that toxicity must be attributed to a toxic factor present in sediment samples, enabling site comparison and identifying pollutants in sediments. Moreover, the significant correlations measured between species in field studies confirmed common response patterns to toxic compounds in the sampled sediments, especially for \u003cem\u003eH. fuscogilva\u003c/em\u003e and \u003cem\u003eL. stylirostris\u003c/em\u003e, although response values may differ. The results indicate, however, that \u003cem\u003eT. gratilla\u003c/em\u003e and \u003cem\u003eH. fuscogilva\u003c/em\u003e exhibited lower larval survival than \u003cem\u003eL. stylirostris\u003c/em\u003e, highlighting the increased sensitivity of echinoderms to single contaminants and environmental matrices from an applied perspective (Pagano et al., \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Morroni et al., 2023). This vulnerability is compounded by their wide distribution, meroplanktonic development, rapid response, and the high sensitivity of their planktonic larvae to various contaminants (Sugni et al., \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2007\u003c/span\u003e). Sea urchins, in particular, play a key role in hard-bottom habitats by regulating plant community dynamics (Grosso et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). They are widely recognized as ideal bioindicators in marine ecotoxicological tests due to the sensitivity of their embryos to the deleterious effects of many contaminants (Pagano et al., \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Gambardella et al., \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Similarly, sea cucumbers play a crucial role in regulating organic matter dynamics and decomposition processes in marine sediments (Pensa et al., \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Grosso et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). However, despite their ecological importance, our understanding of their sensitivity to pollutants remains limited compared to sea urchins. The high sensitivity of \u003cem\u003eT. gratilla\u003c/em\u003e and \u003cem\u003eH. fuscogilva\u003c/em\u003e in our study could provide a differentiated and ecologically valuable response to pollution, offering potential for regular monitoring of sediment quality in French Polynesia and more broadly in tropical waters.\u003c/p\u003e \u003cp\u003eThe interspecific variation underscores the importance of a multi-species approach for a more comprehensive and accurate assessment of ecotoxicological risks, avoiding generalizations that may underestimate or overestimate environmental impacts on a given ecosystem. The variability in sensitivity among species may stem from several factors, including differences in species physiology, larval developmental stages, and mechanisms of tolerance to environmental stressors. A unique aspect of our study is that, unlike all other tested species, we retrieved larvae of \u003cem\u003eL. stylirostris\u003c/em\u003e at the nauplii stage rather than as fertilized eggs. This stage is considered relatively advanced in larval development, which could favor the selection of individuals already more resistant to environmental stressors. Additionally, it is worth noting that the tests were performed during a short perods, decreasing sensitivity. Finally, \u003cem\u003eL. stylirostris\u003c/em\u003e is an introduced species in the Polynesian environment, not naturally occurring. It is typically observed in aquaculture sites, where conditions may be more stressful than in its natural habitat, favoring natural selection in which only individuals most resistant to contaminants reproduce (Li et al., \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2016\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFurthermore, criteria used for toxicity tests, such as exposure durations and larval volume-surface ratio, may also influence the observed results. Feeding may significantly affect larval development and interact with contaminants. Therefore, experiments were performed until larvae began feeding. \u003cem\u003eT. gratilla\u003c/em\u003e and \u003cem\u003eH. fuscogilva\u003c/em\u003e had respective incubation times of 72 hours and 48 hours, while \u003cem\u003eL. stylirostris\u003c/em\u003e had a shorter incubation time of only 40 hours, reducing exposure time, which may partly explain its relatively lower sensitivity in our study.)\u003c/p\u003e \u003cp\u003eResults from field experiments indicated that observed toxicity was highly variable, ranging from − 23–100% abnormal larvae across sampled sites. The relative absence of toxicity observed in the Faratea zone was attributed to the lack of significant pollution sources onshore. While this area has been planned for a regional development project, aimed at developing aquaculture farming for species such as H. fuscogilva and L. stylirostris, this work provides a scientific and technical basis for ongoing monitoring to assess potential changes in toxicity.\u003c/p\u003e \u003cp\u003eUltimately, the variability in sediment toxicity across different Polynesian sites, as a consequence of local pollution sources and specific environmental conditions, highlights the need for continuous and detailed monitoring of marine sediments, as well as the importance of considering local characteristics for effective management of marine ecosystems. In the absence of toxicity assessment standards for the South Pacific, particularly French Polynesia, we believe our results will contribute to the development of standardized tests for more rational risk management related to contaminants from harbor activities, agriculture, riverine inputs, tourism, coastal discharges, harbor dredging sludges, and accidental impact monitoring.\u003c/p\u003e \u003cp\u003eRanking the toxicity results showed priority sites to consider for further experiments and monitoring. These sites include the Vaitepiha estuary in Tautira (T85), Titaaviri in Papeari (T8), Atimaono (T2), Opunohu Bay (T79), Cook Bay (T81), and Haapiti Bay in Moorea (T74), as well as the area around Lake Maeva in Huahine (H13). In absence of chemical analysis, poorly developed in French Polynesia, the potential causes of this contamination remains undetermined but agricultural and urban runoff, as well as industrial effluents are suggested. A study underway on trace metals in algae sampled around Tahiti island, may provide soon insights about the role of urbanization, riverine inputs, winds and rainfalls around the island (Yantouri, \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2019\u003c/span\u003e, Zubia, in preparation), while leaching of contaminants after the weathering of volcanic rocks and soil erosion may contributes to a large amounts of these metals, as a common scheme in coastal waters (Amado Filho et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). Other data on environmental quality are not on chemical pollutants, but bacterial contamination. The link with the toxicity of sediments is not demonstrated, but evidence of bacterial contamination (CSE, 2024) indicates the absence of water treatment in the various towns around the island, and the importance of run offs, that may explain ouputs of contaminants such as in the case of the river mouths of Vaitepiha (T85) or Hitimahana (T43) located at the East coast of Tahiti) where toxicity was high.\u003c/p\u003e \u003cp\u003eWe understand this study has limitations affecting test execution, and interpretation, emphasizing the need to develop more robust handling protocols to ensure the reliability of results in future studies. Attempts to include \u003cem\u003eTridacna maxima, Pinctada margaritifera\u003c/em\u003e, and \u003cem\u003eSaccostrea cucculata\u003c/em\u003e, both representative from the Polynesian ecosystems, were hindered by problems of seasonality, highlighting the importance of conducting tests during optimal maturity periods of the broodstock. Vial’s border effects and excessive thermal exchanges of water and lab during tests that may be lethal to larvae has been critical for some species that are strict in their thermal preference during larval development (\u003cem\u003eH.fuscogilva, T Gracilla\u003c/em\u003e). Additionally, determining the optimal test duration, and the larval developmental stages for the first ever use of \u003cem\u003eH fuscogilva\u003c/em\u003e in toxicity testing was challenging during preliminary experiments. Moreover, not only the tests performed focused on the acute toxicity of sediments, without consideration to chronic toxicity, but representativity could be discussed more. While sediment contamination is considered conservative, sediment structure can vary depending on hydrodynamic conditions, and resuspended contaminated sediments can spread over a much larger area than sampled. Thus, mapping of point toxicity remains indicative, and predictions require closer measurements. Nevertheless, the results show significant potential for chemical toxicity measurements, monitoring of a source or effluent (Merrot et al., \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2022\u003c/span\u003e), and for assessing long-term changes (Kim et al., \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e "},{"header":"Conclusion and perspectives","content":"\u003cp\u003eThe objective of this study was to highlight the toxicity of coastal marine sediments from the Society Islands. Contaminated sediments may affect benthic organisms, which live directly in contact with sediments, as well as necto-benthic species due to the potential release of contaminants into the water column. The results have significant implications for the environmental management of marine ecosystems in French Polynesia. The identification of specific sites with sediment toxicity allows for prioritizing areas for future monitoring and management measures. The variability in sensitivity among the studied species also underscores the need for a multi-species approach to achieve a more comprehensive assessment of environmental impacts.\u003c/p\u003e\u003cp\u003eToxicity tests have demonstrated that sediments from certain sites are harmful to the early developmental stages of tropical organisms. Among the studied species, \u003cem\u003eH. fuscogilva\u003c/em\u003e has never been used for measuring sediment toxicity in natural environments. In addition to its marked sensitivity, this species presents logistical and biological advantages, making it a valuable bio indicator for monitoring chemical contamination in tropical ecosystems. This study provides a relevant protocol that could serve as a reference for future ecotoxicological assessments, development of standardized toxicity tests and further monitoring.\u003c/p\u003e\u003cp\u003eUnderstanding whole sediment elutriates were used for toxicity tests without identifying specific contaminants present, this study establishes the scientific and technical basis for prioritizing sites where contaminants should be identified through analytical chemistry. Future studies should also assess the \u003cem\u003ein vitro\u003c/em\u003e toxicity of major known chemicals used in French Polynesia (e.g., pesticides for agriculture and mosquito control), ensuring a more targeted approach to pollution management and mitigation.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003e\u0026nbsp;Acknowledgements\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was conducted as part of an agreement between the Research Delegation of French Polynesia and IFREMER (agreement 6518 MPR-REC, 2023-2024). We would like to thank all contributors, particularly the teams at IFREMER for their assistance and for providing oyster and sea urchin larvae, as well as Tahiti Marine products (TMP), the VAIA hatchery, and Moerani Lehartel for supplying sea cucumbers, shrimp, and clam larvae, respectively. We also thank David Lecchini (Criobe/CNRS/EPHE) for his logistical support in Bora Bora, as well as Polyn\u0026eacute;sienne des Eaux for providing the boat.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp; \u003cstrong\u003eFunding Declaration\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was funded by the Research Delegation of French Polynesia, under agreement 6518 MPR-REC, 2023-2024.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003e\u003cem\u003eAFNOR (2009). Bio-essai d\u0026rsquo;\u0026eacute;cotoxicit\u0026eacute; aquatique sur le d\u0026eacute;veloppement embryo-larvaire des bivalves. \u003c/em\u003e\u003cem\u003eNF T90 XP-283. \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eAmado Filho, G. M., Andrade, L. R., Karez, C. S., \u0026amp; Farina, M. (2013). Brown algae as biomonitors of coastal contamination by metals. \u003c/em\u003eEnvironmental Research\u003cem\u003e, 132, 345\u0026ndash;361.\u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eAndrefou\u0026euml;t, S., M. Adjeroud.(2019) French Polynesia. In: SHEPPARD, Charles (ed.), World Seas: an Environmental Evaluation (Second Edition)., Chapter 38, Online. Academic Press, 2019. p. 827\u0026ndash;854. \u003c/em\u003e\u003cem\u003ehttps://doi.org/10.1016/B978-0-08-100853-9.00039-7\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eBeiras, R., E. His, M. Seaman (1998). Effects of storage temperature and duration on toxicity of sediments assessed by Crassostrea gigas oyster embryo bioassay. Environmental Toxicology and Chemistry. 1998. Vol. 17, no. 10, p. 2100\u0026ndash; 2105. DOI\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003cem\u003e10.1002/etc.5620171028\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eBlewett, T., K. Ackerly, L. Schlenker, S. Martin, K. Nielsen (2024) Implications of biotic factors for toxicity testing in laboratory studies, Science of The Total Environment, 908, 168220, https://doi.org/10.1016/j.scitotenv.2023.168220.\u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eBonaventura, R., F. Zito, L. Morroni, D. Pellegrini, F. Regoli, A. Pinsino (2021) Development and validation of new analytical methods using sea urchin embryo bioassay to evaluate dredged marine sediments. Journal of Environmental Management, 281, 111862, DOI\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003cem\u003e10\u003c/em\u003e\u003cem\u003e.1016/j.jenvman.2020.111862\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eBoulanger, E., Barst, B.D., Alloy, M., Blais, S., Houde, M., Head, A. (2019) Assessment of environmentally contaminated sediment using a contact assay with early life stage zebrafish (Danio rerio). Science of The Total Environment. 659, 950\u0026ndash;962. DOI\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003cem\u003e10.1016/j.scitotenv.2018.12.265\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eBroccoli, A., L. Morroni, A. Valentini, V. Vitiello, M. Renzi, C. Nuccio, D. Pellegrini (2021) Comparison of different ecotoxicological batteries with WOE approach for the environmental quality evaluation of harbour sediments. Aquatic Toxicology, 237, 105905. DOI\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003cem\u003e10.1016/j.aquatox.2021.105905\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eCarreras, C., V. Ordonez, A. Garcia-Cisneros, O. Wangensteen, C. Palacin, M. Pascual, X. Turon ( 2021). The Two Sides of the Mediterranean: Population Genomics of the Black Sea Urchin Arbacia lixula (Linnaeus, 1758) in a Warming Sea. \u003c/em\u003e\u003cem\u003eFrontiers in Marine Science. Online. 2021. Vol. 8. DOI\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003cem\u003e10.3389/fmars.2021.739008\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eCSE (Centre de Sant\u0026eacute; Environnementale)(2024). Qualit\u0026eacute; bact\u0026eacute;riologique des eaux de baignade. \u0026Iuml;les de Tahiti, Moorea, Bora Bora, Raiatea, Nuku Hiva, Hiva Oa et Tubuai. Campagne 2022-2023. Rapport. Centre de sant\u0026eacute; environnementale, Direction de la sant\u0026eacute; de la Polyn\u0026eacute;sie fran\u0026ccedil;aise. \u003c/em\u003e\u003cem\u003e27 pp.\u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eChen, C., C Ju, Y. Lim, Y. Wang, M.-H., Albarico, F. Paolo Jay B., C. Chen, C. Dong (2022). Potential sources and toxicity risks of polycyclic aromatic hydrocarbons in surface sediments of commercial ports in Taiwan. Marine Pollution Bulletin, Vol. 181, 113924, DOI\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003cem\u003e10.1016/j.marpolbul.2022.113924\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eCrusot, M., T. Gardon, T. Richmond, R. Jezequel, E. Barbier, N. Gaertner-Mazouni (2024) Chemical toxicity of leachates from synthetic and natural-based spat collectors on the embryo-larval development of the pearl oyster, Pinctada margaritifera, Journal of Hazardous Materials, 479, 135647, \u003c/em\u003e\u003cem\u003ehttps://doi.org/10.1016/j.jhazmat.2024.135647\u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eDang, D., N. Layglon, N. Ferretto, D. Omanovic, J. Mullot, V. Lenoble, V., S. Mounier, C. Garnier (2020) Kinetic processes of copper and lead remobilization during sediment resuspension of marine polluted sediments. Science of The Total Environment. 2020. Vol. 698, p. 134120.DOI\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003cem\u003e10.1016/j.scitotenv.2019.134120\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eDuggleby, R.G. (1981) A nonlinear regression program for small computers. Anal Biochem. 1981 Jan 1;110(1):9-18. doi: 10.1016/0003-2697(81)90104-4.\u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003e \u003cem\u003eFinney, D. J. (1971). Probit Analysis (3rd ed.). Cambridge University Press, 333p., \u003cem\u003ehttps://doi.org/10.1002/jps.2600600940\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/em\u003e\u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eGalgani, F., JF. Chiffoleau, V. Orsoni, L. Costantini, Y. Bpoissery, S. Calendini, B. Andral (2006) Chemical contamination and sediment toxicity along the coast of Corsica. \u003c/em\u003e\u003cem\u003eChemistry and Ecology. 2006. Vol. 22, no. 4, 299\u0026ndash;312, DOI\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003cem\u003e10.1080/02757540600812156\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eGalgani, F., Y. Baldi (2010) Evaluation de la toxicit\u0026eacute; globale des s\u0026eacute;diments du littoral du Languedoc Roussillon, du Var et des Alpes Maritimes par un bio essai : D\u0026eacute;veloppement larvaire de l\u0026rsquo;hu\u0026icirc;tre creuse Crassostrea gigas en pr\u0026eacute;sence d\u0026rsquo;\u0026eacute;lutriats de s\u0026eacute;diments. Rapport IFREMER/ LER PAC00028, \u003c/em\u003e\u003cem\u003ehttps://archimer.ifremer.fr/doc/00028/13930/\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eGambardella, C., O. Leggio, A. Montarsolo, A. Harriague, A.0 Covazzi, M. Delcore, M. Faimali, F. Garaventa (2022). \u003c/em\u003e\u003cem\u003eAn integrated approach to characterize deep sediment toxicity in Genoa submarine canyons (NW Mediterranean). Environmental Science and Pollution Research. 2022. Vol. 29, no. 2, 2883\u0026ndash;2893. DOI\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003cem\u003e10.1007/s11356\u003c/em\u003e\u003cem\u003e-\u003c/em\u003e\u003cem\u003e021\u003c/em\u003e\u003cem\u003e-\u003c/em\u003e\u003cem\u003e15807\u003c/em\u003e\u003cem\u003e-\u003c/em\u003e\u003cem\u003e0\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eGambardella, C., F. Marcellini, C. Falugi, S. Varrella, C. Corinaldesi (2021). Early-stage anomalies in the sea urchin (Paracentrotus lividus) as bioindicators of multiple stressors in the marine environment: Overview and future perspectives. \u003c/em\u003e\u003cem\u003eEnvironmental Pollution, 287, 117608. DOI\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003cem\u003e10.1016/j.envpol.2021.117608\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eGoulais, M., D. \u003c/em\u003e\u003cem\u003eSaulnier, J.Rouxel, F. \u003c/em\u003e\u003cem\u003eGalgani (2024). \u003c/em\u003e\u003cem\u003eBioindicator Species of Plastic Toxicity in Tropical Environments. Science of the Total Environment, 954, 176185, \u003c/em\u003e\u003cem\u003ehttps://doi.org/10.1016/j.scitotenv.2024.176185\u003c/em\u003e\u003cem\u003e ,\u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eGrosso, L., A. Rakaj, A. Fiancini, L. Tancioni (2022) Trophic Requirements of the Sea Urchin Paracentrotus lividus Varies at Different Life Stages: Comprehension of Species Ecology and Implications for Effective Feeding Formulations. Frontiers in Marine Sciences, vol 9, \u003c/em\u003e\u003cem\u003eDOI:\u003c/em\u003e\u003cem\u003e10.3389/fmars.2022.865450\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003e \u003c/em\u003e\u003cem\u003eGrosso, L., M. Rampacci, D. Pensa, A. Fianchini, E. Batir, I Aydain, L. Ciriminna, P. Felix, A. Pombo, A. Lovatelli, S. Vizzini, M. Scardi, A. Rakaj (2023) Evaluating sea cucumbers as extractive species for benthic bioremediation in mussel farms. Scientific Reports. 2023. Vol. 13. DOI\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003cem\u003e10.1038/s41598\u003c/em\u003e\u003cem\u003e-\u003c/em\u003e\u003cem\u003e023\u003c/em\u003e\u003cem\u003e-\u003c/em\u003e\u003cem\u003e28733\u003c/em\u003e\u003cem\u003e-\u003c/em\u003e\u003cem\u003e7\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eHajji, A., Lucas, K. (2024) Anthropogenic stressors and the marine environment: From sources and impacts to solutions and mitigation, Marine Pollution Bulletin, 205, 116557,https://doi.org/10.1016/j.marpolbul.2024.116557.\u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eHarris, C. R., Millman, K. J., van der Walt, S. J., et al. (2020). Array programming with NumPy. Nature, 585(7825), 357\u0026ndash;362. https://doi.org/10.1038/s41586-020-2649-2\u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eHama Aziz, K., F.S. Mustafa, K.M. Omer, S. Hama, R. Fayaq Hamarawf, K. Othman Rahma (2023) Heavy metal pollution in the aquatic environment: efficient and low-cost removal approaches to eliminate their toxicity: a review. \u003c/em\u003e\u003cem\u003eRSC Adv.\u003c/em\u003e\u003cem\u003e, 2023, 13, 17595-17610, \u003c/em\u003e\u003cem\u003ehttps://pubs.rsc.org/en/content/articlehtml/2023/ra/d3ra00723e\u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eHodge, A., F. Hopkins, M. Saha, A. Jha-(2025) Ecotoxicological effects of sunscreen derived organic and inorganic UV filters on marine organisms: A critical review, Marine Pollution Bulletin, 213, 117627,https://doi.org/10.1016/j.marpolbul.2025.117627.\u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eKim, S., S. Hong, J. Lee, T. Kim, T. Yoon, J. Lee, K. Choi, B Kwon, J. Giesy, J. Khim (2020) Long-term trends of persistent toxic substances and potential toxicities in sediments along the west coast of South Korea. Marine Pollution Bulletin. 2020. Vol. 151, 110821. DOI\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003cem\u003e10.1016/j.marpolbul.2019.110821\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eLeistenschneider, D., Wolinski, A., Cheng, J., Ter Halle, A., Duflos, G., Huvet, A., Paul-Pont; I, Lartaud, F., Galgani, F., Lavergne, E., Meistertzheim, A., Ghiglione, J.F., (2023). A critical review on the evaluation of toxicity and ecological risk assessment of plastics in the marine environment . Science of the Total Environment, 896, 164955 (15p.), \u003c/em\u003e\u003cem\u003ehttps://doi.org/10.1016/j.scitotenv.2023.164955\u003c/em\u003e\u003cem\u003e , \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eLi, W., X.Lu, S.Luan, K. Luo, J. Sui ; J. Kong (2016) Heritability of body weight and resistance to ammonia in the Pacific white shrimp Litopenaeus vannamei juveniles | Journal of Oceanology and Limnology.34, 1025-1033, \u003c/em\u003e\u003cem\u003ehttps://link.springer.com/article/10.1007/s00343\u003c/em\u003e\u003cem\u003e-\u003c/em\u003e\u003cem\u003e016\u003c/em\u003e\u003cem\u003e-\u003c/em\u003e\u003cem\u003e5034\u003c/em\u003e\u003cem\u003e-\u003c/em\u003e\u003cem\u003e0\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eMerrot, P., F. Juillot, L. Flipo, M. Tharaud, E. Viollier, V. Noel, P. Le pape, J.M. Fernandez, B. Torreton, G. Morin (2022). Bioavailability of chromium, nickel, iron and manganese in relation to their speciation in coastal sediments downstream of ultramafic catchments: A case study in New Caledonia. Chemosphere. 302, 134643. DOI\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003cem\u003e10.1016/j.chemosphere.2022.134643\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eMkuye, R., C. Yang, F. Masanja, S. Ibrahim, X. Yang, H.Mwemi, P.Mrope, M.Salman, A.Alfatat, Y.Deng (2025) Omics insights in responses of bivalves exposed to plastic pollution, Aquatic Toxicology, 279, 107224, https://doi.org/10.1016/j.aquatox.2024.107224.\u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eMorroni, L., A. Rakaj, L. Grosso, A FIanchini, D. Pellegrini, F. Regoli (2020) Sea cucumber Holothuria polii (Delle Chiaje, 1823) as new model for embryo bioassays in ecotoxicological studies. Chemosphere. 2020. Vol. 240, p. 124819. DOI\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003cem\u003e10.1016/j.chemosphere.2019.124819\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eMorroni, L., A. Rakaj, L. Grosso, A FIanchini, D. Pellegrini, F. Regoli (202). Echinoderm larvae as bioindicators for the assessment of marine pollution: Sea urchin and sea cucumber responsiveness and future perspectives. Environmental Pollution, 335, 122285. DOI\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003cem\u003e10.10\u003c/em\u003e\u003cem\u003e16/j.envpol.2023.122285\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eMount, D. R., Gulley, D. D., Hockett, J. R., Garrison, T. D., \u0026amp; Evans, J. M. (1997). Use of a Weibull model to estimate EC50s and confidence intervals in toxicological bioassays. Environmental Toxicology and Chemistry, 16(7), 1291\u0026ndash;1294. https://doi.org/10.1002/etc.5620160706\u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eMuller-Karanassos, C., W. Arundel, P. Lindeque, T. Vance, A. Turner, M. Cole (2021) Environmental concentrations of antifouling paint particles are toxic to sediment-dwelling invertebrates. Environmental Pollution, 268, 115754. DOI\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003cem\u003e10.1016/j.envpol.2020.115754\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eNorberg-King, T. J. (1993). A linear interpolation model for estimating EC50s and IC50s. EPA Report 600/3-91/055. U.S. Environmental Protection Agency, Duluth, MN.\u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eOsunde, I., S. Coyle, J. Tidwell (2004) Acute Toxicity of Copper to Juvenile Freshwater Prawns, Macrobrachium rosenbergii : Journal of Applied Aquaculture, 14:3-4, 71-79, \u003c/em\u003e\u003cem\u003ehttps://www.tandfonline.com/doi/abs/10.1300/J028v14n03_06\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003ePensa, D., A. Fianchini, L. Grosso, D. Ventura, S. Cataudella, M. Scardi, A Rekaj (2022) Population status, distribution and trophic implications of Pinna nobilis along the South-eastern Italian coast. Biodiversity. 2022. Vol. 1. DOI\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003cem\u003e10.1038/s44185\u003c/em\u003e\u003cem\u003e-\u003c/em\u003e\u003cem\u003e022\u003c/em\u003e\u003cem\u003e-\u003c/em\u003e\u003cem\u003e00002\u003c/em\u003e\u003cem\u003e-\u003c/em\u003e\u003cem\u003e2\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003ePagano, G., M. Guida, M. Trifuoggi, P. Thomas, A. Palumbo, G. Romanov, R. Oral (2017) Sea Urchin Bioassays in Toxicity Testing: I. Inorganics, Organics, Complex Mixtures and Natural Products. Expert Opinion on Environmental Biology. Online. 2017. Vol. 06, no. 01, DOI\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003cem\u003e10.4172/2325\u003c/em\u003e\u003cem\u003e-\u003c/em\u003e\u003cem\u003e9655.1000142\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eRakaj, A., L. Morroni, L. Grosso, A. Fianchini, D. Pensa, D. Pellegrini, F Regoli (2021) Towards sea cucumbers as a new model in embryo-larval bioassays: Holothuria tubulosa as test species for the assessment of marine pollution. Science of The Total Environment, Vol. 787, p. 147593. DOI\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003cem\u003e10.1016/j.scitotenv.2021.147593\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eReguera, P., L. Couceiro, N. Fernandez (2018) A review of the empirical literature on the use of limpets Patella spp. (Mollusca: Gastropoda) as bioindicators of environmental quality. Ecotoxicology and Environmental Safety. 2018. Vol. 148, p. 593\u0026ndash; 600. DOI\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003cem\u003e10.1016/j.ecoenv.2017.11.004\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eRitz, C., Baty, F., Streibig, J. C., \u0026amp; Gerhard, D. (2015). Dose\u0026ndash;Response Analysis Using R. PLOS ONE, 10(12), e0146021.\u003cbr\u003e \u003c/em\u003e\u003cem\u003ehttps://doi.org/10.1371/journal.pone.0146021\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eRuocco, N. I. Bertocci, M. Munari, L. Musco, D. Caramiello, R. Danovaro, V. Zupo, M. Costantini (2020) Morphological and molecular responses of the sea urchin Paracentrotus lividus to highly contaminated marine sediments: The case study of Bagnoli-Coroglio brownfield (Mediterranean Sea). \u003c/em\u003e\u003cem\u003eMarine Environmental Research. 154, 104865, DOI\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003cem\u003e10.1016/j.marenvres.2019.104865\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eSalvat, B., H. Roche, P. Berny, F. Ramade (2012) Recherches sur la contamination par les pesticides d\u0026rsquo;organismes marins des r\u0026eacute;seaux trophiques r\u0026eacute;cifaux de Polyn\u0026eacute;sie fran\u0026ccedil;aise. \u003c/em\u003e\u003cem\u003eRevue d\u0026rsquo;\u0026Eacute;cologie. 2012. Vol. 67, no. 2, p. 129\u0026ndash; 147.\u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eSchiwy, S., M. Velki, H. Hollert (2020). Whole-Sediment Toxicity Bioassay to Determine Bioavailability and Effects of Aquatic Contaminants Using Zebrafish Embryos. In: Seiler, T.B., Brinkmann, M. (eds) In Situ Bioavailability and Toxicity of Organic Chemicals in Aquatic Systems. Methods in Pharmacology and Toxicology. Humana, New York, NY. \u003c/em\u003e\u003cem\u003ehttps://doi.org/10.1007/7653_2020_42\u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eSciarrillo, R., D. Zuzolo, D. Cichella, F. Lannone, G. Camino, C. Guarino (2020) Contamination and ecological risk assessment of the seaport of Naples (Italy): Insights from marine sediments. Journal of Geochemical Exploration. 2020. Vol. 210, 106449. DOI\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003cem\u003e10.1016/j.gexplo.2019.106449\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eSugni, M., D. Mozzi, A. Barbaglio, F. Bonasoro, MD. Candia Carnevall (2007) Endocrine disrupting compounds and echinoderms: new ecotoxicological sentinels for the marine ecosystem. Ecotoxicology (London, England). 2007. Vol. 16, no. 1, p. 95\u0026ndash;108. DOI\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003cem\u003e10.1007/s10646\u003c/em\u003e\u003cem\u003e-\u003c/em\u003e\u003cem\u003e006\u003c/em\u003e\u003cem\u003e-\u003c/em\u003e\u003cem\u003e0119\u003c/em\u003e\u003cem\u003e-\u003c/em\u003e\u003cem\u003e8\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eUSEPA (1993) Methods for Measuring the Acute Toxicity of Effluents and Receiving Waters to Freshwater and Marine Organisms, 4th edition, 273 pages, EPA-821-R-02-012. \u003c/em\u003e\u003cem\u003ewww3.epa.gov/npdes/pubs/atx.pdf\u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eUS EPA (2002)- Short-Term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Marine and Estuarine Organisms. Fourth edition, 350p., EPA-821-R-02-014\u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eVirtanen, P., Gommers, R., Oliphant, T. E., et al. (2020). SciPy 1.0: Fundamental Algorithms for Scientific Computing in Python. \u003c/em\u003e\u003cem\u003eNature Methods, 17, 261\u0026ndash;272. https://doi.org/10.1038/s41592-019-0686-2\u003c/em\u003e\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eYANTOURI, S. (2019) Les algues polyn\u0026eacute;siennes : Quelles potentialit\u0026eacute;s de valorisation au regard de leur teneurs en m\u0026eacute;taux toxiques ? M\u0026eacute;moire de stage de Master 2, Ann\u0026eacute;e universitaire: 2018-2019, Universit\u0026eacute; de Bretagne Occidentale, 36 pp\u003cem\u003e\u003cem\u003e \u003c/em\u003e\u003c/em\u003e\u003c/em\u003e\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Ecotoxicology, Bioassays, Sediments, Indicators, Reef ecosystems, French Polynesia","lastPublishedDoi":"10.21203/rs.3.rs-6711214/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6711214/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eAquatic sediments act as reservoirs of multiple sources of pollutants, and the increasing urbanization of coastal marine areas generally contributes to the accumulation of contaminants, endangering aquatic life and biodiversity. In the present study, we assessed the toxicity of sediment sampled at 150 sites around six islands in the Society Archipelago, French Polynesia. This evaluation is based on the use of standardized biological assays, during larval development of tropical benthic species systems in sediment elutriates. The results have shown a significant correlation in the responses of the four species studied: the oyster Saccostrea cucculata, the sea cucumber Holothuria fuscogilva, the sea urchin Tripneustes gratilla, and the shrimp Litopenaeus stylirostris. Larvae of Holothuria fuscogilva and Tripneustes gratilla were the most sensitive and suitable for assessing sediment quality.\u003c/p\u003e\n\u003cp\u003eData mapping revealed high toxicity, up to 100% mortality of larvae, in selected sites such as the Vaitepiha river mouth, Titaaviri, Atimaono in Tahiti Islans, as well as ‘Ōpūnohu Bay, Cook Bay, and Haapiti Bay in Moorea, and lake Maeva in Huahine. This toxicity is attributable to various sources of pollution, including agricultural, urban runoff and industrial effluents, as well as harbor and leisure activities. This study provides a significant contribution by identifying species that will provide essential predictive tools for adaptive management of tropical lagoons and identifying areas that showed high rates of developmental anomalies, requiring increased monitoring.\u003c/p\u003e","manuscriptTitle":"Assessment of Sediment Quality and Vulnerability of Tropical Marine Species in the Society Islands, French Polynesia","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-06-05 19:28:04","doi":"10.21203/rs.3.rs-6711214/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"af4ec0f7-acb0-476d-ab10-70ce4de89538","owner":[],"postedDate":"June 5th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-07-07T13:08:26+00:00","versionOfRecord":[],"versionCreatedAt":"2025-06-05 19:28:04","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6711214","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6711214","identity":"rs-6711214","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}