Squat lobster latitudinal life habitat shifts and metabolic response to combined temperature and oxygen conditions in the Humboldt Current System

Squat lobster latitudinal life habitat shifts and metabolic response to combined temperature and oxygen conditions in the Humboldt Current System | 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 Article Squat lobster latitudinal life habitat shifts and metabolic response to combined temperature and oxygen conditions in the Humboldt Current System María de los Ángeles Gallardo, Kurt Paschke, Katherina Brokordt, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6198822/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 21 Nov, 2025 Read the published version in Scientific Reports → Version 1 posted 12 You are reading this latest preprint version Abstract We examined how a species inhabiting a latitudinal gradient from surface oxygenated warm waters to subsurface severely oxygen-limited cold waters along the continental shelf of the Eastern South Pacific (ESP) is responding to the latitudinal temperature changes of low oxygen isopleths. We combined temperature-oxygen latitudinal sections from World Ocean Database, historical recordings of pelagic/benthic Grimothea monodon occurrence through latitude and conducted laboratory experiments assessing juvenile’s routine and postprandial metabolism at realistic oxygen-temperature conditions. S quat lobsters main habits (pelagic to benthic) were related with temperature at the 2 ml O 2 L − 1 (~ 89 µM) oxygen isopleth. Warm (> 15°C) hypoxic upper oxygen minimum zone (OMZ) impairs G. monodon all time permanence on benthic habitat or restrict it to pelagic habits. The physiological performance of juveniles (main migratory stage) was negatively affected by high temperature-hypoxia interaction. Routine metabolic rates showed a 60% decrease with hypoxia at high temperatures (21°C). Postprandial metabolism (as SDA) was mostly affected at high temperatures and low oxygen. Grimothea monodon can adjust their life habits to a wide range of conditions along the ESP coast maintaining intergenerational capability to shift from one habit to the other, their expansion/restriction in vertical distribution, would allow for maintaining/expanding latitudinal ranges as benthic and pelagic food webs adjust to its availability as key prey item and humans to future fishing grounds. Biological sciences/Biophysics Biological sciences/Ecology Biological sciences/Physiology Earth and environmental sciences/Ecology Earth and environmental sciences/Environmental sciences Earth and environmental sciences/Ocean sciences Global Climate Change and phenotypic plasticity Pleuroncodes monodon “munida” squat lobster temperature-oxygen metabolic responses Humboldt Current System OMZ Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 INTRODUCTION Changes in oxygen availability and thermal conditions represent challenges that marine species must overcome in the face of global climate change scenarios 1 . Ocean oxygen depletion and temperature rise are expected to restrict the suitable habitat of marine invertebrates in the near future 2 due to their metabolic thresholds 1 . Responses at individual/ population level growth and reproduction as well as species biogeographical distributions are expected 3 . The effects of temperature and oxygen on the physiology of ectotherm organisms have been studied mainly in species inhabiting coastal environments 4 , but are scarce in organisms inhabiting oxygen minimum zones (OMZ) 5 that already display complex physiological adaptations to overcome oxygen-poor, but mainly cold conditions 6 . Few species are reported having a geographic distribution extending across hypoxic conditions (as prevailing in OMZs) and pronounced temperature gradients. A methodological approach to infer the future shifts of OMZs on population parameters and distribution is to evaluate the current distribution and life cycle characteristics of species that occupy contrasting temperature and oxygen conditions together with their ecophysiological and metabolic characteristics. This approach should allow to evaluate novel expected responses to future environmental physicochemical conditions for these type of organism. Hypoxia may affect routine metabolic rates and aerobic scope, of metazoan organisms (within species-specific tolerance thresholds), limiting the supply of cellular oxygen and ultimately affecting the production of energy (ATP) by aerobic metabolic pathways 7 . OMZ organisms usually keep oxygen provision independent from ambient concentrations down to very low levels (oxyregulation) 8 . Nevertheless, routine metabolic demands increase with temperature thus i) rising the oxygen tension below which oxyregulation no longer takes place (critical points Pcrit) and ii) reducing aerobic scope (organism capacity to uptake oxygen above routine metabolic rate RMR), an indicator of aerobic performance and individual fitness 4 . Therefore, temperature variability associated with the upper OMZ boundary (0.5-2.0 ml O 2 L − 1 ) is expected to have strong metabolic and biological effects on organisms 9 as shown for temperature/oxygen modulation of individual fish performance 10 . Grimothea monodon (H. Milne Edwards, 1837), a decapod crustacean (Munididae) widely quoted in the literature as Pleuroncodes monodon until the recent reconsideration of its taxonomic status 11 , is distributed along the Pacific coast of America, from ~ 15°N to ~ 40°S 12 . Its capacity to withstand low oxygen concentrations have been proven from field campaigns 13 , 14 and laboratory experiments, although severe hypoxia exerts metabolic, physiological and behavioural sublethal effects 15 , 16 . Thus, it can be considered an ideal model species to examine its response to latitudinal sections of temperature and oxygen concentration within its distribution range. Between Peru and Chile, the OMZ becomes narrower, thinner and deepens with latitude 17 while sea surface temperature diminishes (> 23°C to 12°C) 18 . At ~ 7°S for example, large pelagic populations of the species occupy surface waters above the oxycline during day and night hours 19 , 20 , south of 25°S adults sustain an important benthic trawling fishery on the poorly oxygenated continental shelf (e.g. ~34–37°S) 21 , and limited observations show adult vertical migration are plausible in Peruvian margins 16 . The high phenotypic plasticity of Grimothea monodon 22 have also an expression on the smaller adult and size at maturity in northern pelagic populations 23 , 24 compared to southern benthic ones. Life in benthic habitats is attained in southern populations after a juvenile stage that migrates daily from surface waters to the benthos 25 , and to the best of our knowledge there are no reports of pelagic ovigerous females in these southern latitudes. So far, a qualitative literature review points to both temperature and hypoxia among the potential drivers of shifting plastic habits of the species 26 , nevertheless neither the upper OMZ-temperature association with latitude over the continental shelf of the Humboldt Current System (HCS) has been described yet, nor its quantitative relationship with the species life habitats. The physiological and ecological restrictions that the juveniles would confront developing as vertical migrators from warm oxygenated waters to deep colder hypoxic waters. could be key determinants of the later habits and adult population parameters. We hypothesize that the prevalent adult life habit segregation (pelagic/benthic) within the 5°S to 35°S latitudinal range of our study (Fig. 1 A). is associated with the latitudinal variability of temperature-oxygen oceanographic conditions over the continental shelf that varies between 10 to 100 km width (Fig. 1 B). Also, naturally occurring combinations of temperature-oxygen levels within this distribution range impose metabolic constraints on juveniles. In order to evaluate our hypothesis, we first reconstructed the mean latitudinal distribution of water temperature and oxygen characteristics over the continental shelf. Second, we conducted an exhaustive review on the occurrence of pelagic/benthic G. monodon throughout the same latitudinal range. Third, we related the presence/absence of each life habit (pelagic or benthic) with the latitudinal oceanographic reconstruction. Finally, we experimentally determined metabolic responses of juveniles to combined temperature and dissolved oxygen (DO) conditions within natural ranges on routine and post-prandial metabolic rates (specific dynamic action, SDA) and metabolic enzyme activities. RESULTS Latitudinal oceanography Based on World Ocean Database (WOD) oceanographic profiles (1969–2008) for the Eastern South Pacific (ESP) continental shelf (Fig. 1 A, B), hypoxic waters are colder than more oxygenated surface waters. The mean temperature associated with the OMZ limits (as 2, 1, and 0.5 ml L − 1 oxygen isopleth) decreased with latitude (Fig. 1 C). At 14–16°S, the temperature were 16°C, 14.9°C and 14.1°C, respectively, while they descended to 12.3°C, 12.1°C and 11.8°C between 23–37°S, for each oxygen isopleth. Isopleths depth do not trend monotonically over the continental shelf (Fig. 1 D) and in general low oxygen waters (below 1 ml L − 1 ) also showed a decrease in temperature with latitude: 15°S 12–18°C, 22°S 12–14°C and 35°S 10-11.5°C (Fig. 1 E). Although less marked, the pattern can even be observed on sections from the gridded World Ocean Atlas (WOA), that include offshore conditions (Supplementary Fig. S1 online). Mean surface temperatures over the continental shelf range from ~ 11ºC in the subtropical region (35–37°S) to ~ 20ºC in the northern HCS (Fig. 1 E, 2 A) and the largest latitudinal surface temperature gradient was observed between 27°S and 20ºS. Vertical temperature profiles and temperature at isopleth display a wider range in northern latitudes. The 2 ml L − 1 oxygen isopleth deepened south of 18°S from 15m to 50m, while the 1 and 0.5 ml L − 1 also deepened north of 8°S (Fig. 1 D, 2 B). The depth of the 0.5 ml L − 1 oxygen isopleth followed neither a monotonic trend with latitude nor shelf width latitudinal variability (Fig. 1 B, D, Fig. 2 B). Presence/absence of Grimothea monodon in pelagic and benthic zones : The latitudinal distribution of G. monodon adult habitat shows a break between 20°S and 23°S (Fig. 2 C). Out of 37 demersal/benthic studies between 1965 and 2015 between 5°S and 38°S (Table S1 ), 16 studies reported benthic G. monodon systematically north of 9°S and south of 20°S-23°S (Fig. 2 C). North of 9°S, benthic G. monodon appeared between 1996 and 2014 at low densities (Supplementary Table S1 online) as bycatch and food item of Peruvian hake 27 . South of 20°S-23°S, G. monodon sustains large benthic biomasses, (targeted by trawling fishery; bycatch and food item of Chilean hake 28 ). Benthic densities in Chile have been one to two orders of magnitude higher than those ever recorded in Peru. Important biomasses of pelagic (adult) G. monodon have been revealed during small pelagic fish assessments between 6°S and 18°S, overlapping with the Engraulis ringen s distribution over the Peruvian continental shelf from 1988 onwards 20 . North of 9°S, benthic and pelagic forms coexist. In Chile, G. monodon small pelagic assessments have revealed G. monodon pelagic forms only between 20°S and 18°S, as anchovy bycatch 29 , but never south of those latitudes even though such assessments extend to 40°S (Table S1 ). The Peruvian Institute of the Sea (IMARPE) undertook campaigns (1970–1972) from 12°S to 18°S dedicated to explore potential fisheries of benthic crustaceans. G. monodon was found at a single 40 m depth station, 16.5°S during 1972 (El Niño) at low densities (Table S1 ). Two records of benthic G. monodon were found at 12.2°S: i) Seven individuals caught at 160 m depth during 1965 (El Niño) 30 and ii) 11 individuals at 71 and 145 m depth in 2013, neutral conditions 16 , and hypoxic waters ~ 1 ml L − 1 . Temperatures associated with the limits of the OMZ as 0.5, 1 or 2 ml L − 1 oxygen isopleth as well as oxygen isopleth depths significantly explained the shift in G. monodon habitat use, accounting for 90% of the variance (Random Forest analysis, Supplementary Table S2 online). The first model fitted including all the predictor variables, explained 90.9% (Pseudo-R 2 ) of the variance. The exclusion of variables of lower “Mean Decrease Accuracy” (shelf width and depth of 0.5 ml L − 1 oxygen isopleth), improved variance explanation to 93.9%. The models break down the probability of predicting each scenario, both models had 100% accuracy in predicting benthic habitat as low temperatures associated to the limits of the OMZ ( 50 m). The prediction of pelagic habit had a success rate of 91.7%: when the limits of OMZ (2 and 1 ml L − 1 ) are associated with high temperatures (> 15°C) and shallow location (< 50 m). The prediction of co-occurrence of benthic and pelagic habits had an accuracy of 66.7%. The presence of co-occurrence is related to the deepening of the limits of 1 and 0.5 ml L − 1 under 90 m and a wide shelf (> 50 km) (Figs. 1 and 2 ). Ecophysiology of Grimothea monodon Metabolic rates of G. monodon juveniles were significantly affected by temperature, oxygen concentration and their interaction in both fasting and fed conditions. The routine metabolic rate (RMR) of G. monodon juveniles increased with temperature, almost tripling oxygen consumption from 11°C to 21°C in normoxia (Fig. 3 A). At 11°C, juveniles metabolic rate was low (mean = 0.13 ± 0.03 mg O 2 h − 1 g − 1 ) and independent of DO condition within the DO range evaluated (Pcrit at 11°C below our lowest condition, < 1.4 kPa; 0.6 mgO 2 L − 1 ). At 21°C oxyregulatory response was observed down to a Pcrit of 7 kPa (2.5 mg O 2 L − 1 ). Oxygen consumption decreased from a mean of 0.32 ± 0.07 mg O 2 h − 1 g − 1 (above the Pcrit) to 0.23 ± 0.05 mg O 2 h − 1 g − 1 at the lowest oxygen concentration analyzed (> 1.4 kPa), a 60.3% of the SMR (Fig. 3 A). The breaking point was significant. The apparent specific activity of LDH (Lactate dehydrogenase) in juveniles of G. monodon was higher with increasing temperature and hypoxia. LDH activity remained relatively stable in juveniles kept at 11°C (mean = 4.45 ± 1.06 UI LDH g − 1 ), throughout the range of DO analyzed. At 21°C the apparent specific activity of LDH increased from 5.22 (above the Pcrit) to 7.23 UI LDH g − 1 , at the lowest oxygen level considered (Fig. 3 B). Temperature significantly affected RMR in postprandial metabolic experiments depending on oxygen concentrations. RMR increased with temperature at normoxia and at 2.9 mg L − 1 , but at 1.4 and 0.7 mg L − 1 the maximum SMR occurred at 15°C (Fig. 4 A, Supplementary Table S3 online). Consistent with previous experiments, at 11°C juveniles maintained their SMR throughout the DO levels analyzed (Fig. 3 A and 4 A). At 21°C SMR decreased with decreasing DO; the reduction from normoxia to 2.9 mg L − 1 was similar to the previous experiments and was further reduced at 0.7 and 1.4 mg L − 1 , although consumption did not differ significantly between the latter (Fig. 4 A). At 15°C, SMR in normoxia was higher only in comparison with the lowest oxygen treatment (Fig. 4 A, Supplementary Table S3 online). The peak of the postprandial metabolic curve was modulated by temperature and DO (Fig. 4 B). Overall it decreased with decreasing oxygen concentrations at all temperatures but differing slopes/shapes. The decrease was steeper at 21ºC than at 15°C and 11°C; no peak was measured at 0.7 mgL − 1 for 21°C. At 11ºC, the difference was only significant between normoxia-2.9 and 1.4–0.7 mg L − 1 treatments. Only in normoxia postprandial peak increased with temperature. In general, the postprandial metabolic scope increased with oxygen concentration for all temperatures, and it was higher for low temperatures regardless of the DO treatment (Fig. 4 C, Supplementary Table S3 online). The postprandial metabolic duration decreased with decreasing oxygen concentrations and the decline was steeper at higher temperatures. At 11°C and 15ºC, it decreased from normoxia to 2.9 mg L − 1 remaining constant in the other oxygen treatments, while at 21ºC, it decreased through all hypoxia treatments. In normoxia, postprandial metabolic duration was marginally longer at 21°C, while in hypoxia (0.7 and 1.4 mg L − 1 ) the time decreased significantly with increasing temperature (Fig. 4 D). In normoxia, the accumulated energy expended during the postprandial metabolic response was related significantly with temperature and oxygen. The accumulated energy SDA decreased 85 to 90% from normoxia to 2.9 mg L − 1 for all temperatures. The decrease below 2.9 mg L − 1 was steepest at 21°C, reaching 0 al 0.7 mg L − 1 , and it was not significant for 15°C and 11ºC. Under hypoxia, there were no significant differences between temperatures (Fig. 4 E; Supplementary Table S3 online). For LDH activity a significant effect of both temperature ( p = 0.001) and DO concentration ( p = 0.007) was observed. At 21°C, LDH activity remained constant and low (~ 3 UI g − 1 ) throughout different DO concentrations. At 15°C, LDH activity only increased at 0.7 mg L − 1 (mean 9.3 UI g − 1 ), while at 11°C, high LDH activities were observed from 2.9 mg L − 1 to the lower DO concentrations evaluated. Overall, LDH activity decreased with temperature (Fig. 5 A). The concentration of HSP70 was significantly affect by DO ( P = 0.0143) but not by temperature ( p = 0.67). The highest concentration of HSP70 was found at 0.7 mg L − 1 (mean = 1.3 HSP70 mg protein − 1 ) (Fig. 5 B). DISCUSSION The shallow depth of the oxycline had previously been viewed as the main cause for the shift of adult Grimothea monodon 20 from benthic habitats in southern-central Chile to pelagic habits in southern Peru. Nevertheless, why low-oxygen levels were avoided at low latitudes while at higher latitudes they inhabited hypoxic bottom waters remained open. Our study shows that the most conspicuous adult habitat shift was related with the temperature of the upper OMZ as well as its depth, so warm hypoxic waters seem to restrict G. monodon above oxygen isopleth (2 ml O 2 L − 1). We also show that juvenile stages might be metabolically restricted by hypoxia at realistic warm temperatures, as evidenced by the significant decreases in SDA (accumulated energy) in those conditions. Juveniles are known to migrate daily between surface oxygenated and cold hypoxic demersal waters in northern-central and southern-central Chile 13 , 25 . Resting metabolic rates show no decrease with low oxygen concentrations at 11°C but they do at 15°C and especially at 21°C and postprandial metabolism is restricted under warm hypoxic conditions. Thus, the constraints that squat lobsters start experiencing during the juvenile phase might dictate their future life habit (benthic or pelagic) and the observed latitudinal shift in habitat use. Throughout the latitudinal range considered, oxygen concentrations below 1 ml L − 1 and 0.5 ml L − 1 were frequent in subsurface waters over the continental shelf. The upper limit of the OMZ has been described to deepen with latitude and is generally assumed to reach depths larger than 100 m towards 37ºS 31 , 32 . Nevertheless, when only oxygen profiles above the continental shelf (< 200 m) are evaluated, the presence of a shallower OMZ becomes evident throughout the Chilean continental shelf, as described for the Concepción area 33 . Low oxygen conditions are usually associated with "cold" waters 13 , but the latitudinal variability of "cold" conditions had not previously been analyzed, despite of the known interactive effect of temperature and oxygen concentration on the metabolism of ectothermic species 7 and its overall importance for all metabolic and geochemical processes. The latitudinal difference of temperature for the OMZ upper limit can vary between 4–7°C and the thermal gradient across the oxycline varies from 2°C in the south to 6°C at low latitudes (Supplementary Fig. S2 online). Our review revealed that thermal and oxygen latitudinal variations were significantly associated with changes in adult life habits. Several members of the family Munididae are characterized by bentho-pelagic habits with ( Grimothea gregaria ) 34 , 35 or without ( G planipes 36 and G quadrispina 37 ) significant differences in morphology between pelagic and benthic adult morphologies, but significant larger sizes in benthic environments. In the case of G. monodon , the use of different habitats was explained by the variability of the structure of temperature/oxygen profiles with latitude (R = 90.9), whereas changes in life history (longevity, maximum size, and first sexual maturity) may respond to latitudinal variability of temperature (Figs. 1 and 2 ). In Peru adult pelagic squat lobsters are captured at temperatures between 16°C and 23°C 38 , while in Chile they are caught in the benthos at 11°C-12°C 14 ). The size (CL–Carapace Length) at sexual maturity differs by ~ 6–8 mm between pelagic (Peru, CL 10 mm) and benthic (Concepción, Chile, CL > 18 mm) individuals 39 , 40 . Our observations do not contradict the expected temperature-size relationship characteristic of ectotherm taxa 41 , 42 . Temperature also show a direct relationship between longevity and size at first sexual maturity, as well as maximum adult size since the dependence of development on temperature is steeper than that of growth. Meeting the oxygen requirements necessary to support the expected increase on metabolic rates (RMR, postprandial metabolism) from 11°C to 15–18ºC is restricted for juveniles at the oxygen concentration typical of the upper OMZ. In addition, the increase in temperature affects the solubility of oxygen, which is why under hypoxic conditions the availability of oxygen is expected to be reduced in warm conditions 43 . Together warm hypoxic conditions would restrict both habitat suitability and attainable size 41 . Further support for the temperature & oxygen isopleth habitat restriction explanation, is provided by the systematic observation of G. monodon benthic adults between 6°S and 7°S and their eventual presence at 11°S and 16°S 16 , 30 . Between 6°S and 7°S, the OMZ deepens due to intrusion of the Cromwell current (high in oxygen and nutrients) 44 , whereas the few benthic individuals recorded at 11°S, 12°S and 16°S were collected during ENSO warm years (2002, 1967, 1972 respectively), when the OMZ retreats offshore to deeper depths. In both scenarios the condition of a shallow-warm oxygen isopleth are broken. The results of RMR, Pcrit and postprandial experiments in the different realistic scenarios of temperature/DO evaluated were in agreement with the field observations on habitat use and plasticity with latitude. As expected, an interactive effect of temperature and oxygen concentration was observed on metabolic rates of G. monodon juveniles. First RMR increased with temperature between 11°S and 21°C, the temperature range inhabited by natural populations in normoxia. The Pcrit for RMR was detected at high temperatures (6.7 kPa), but not at 11°C (within the range of kPa evaluated) in G. monodon juveniles, regardless of feeding condition (starvation vs post-prandial measurements). RMR values for G. monodon juveniles are in agreement with those expected from the log (weight specific respiration rate) to log (individual weight) relationship through the species life cycle (Supplementary Fig. S1 online) also described for other crustaceans 45 , as well with those reported for the same species 16 . In G. planipes Pcrit was detected at 0.1 mg L − 1 (0.24 kPa at 10°C 47 , and 0.5 kPa at 13°C 16 ). This is coincident with expected results for ectotherms that within species-specific ranges show higher RMR as well as Pcrit at higher temperatures 46 , and also with observations of other squat lobster species, such as Galathea strigose 48 and adult Grimothea planipes (ex Pleuroncodes planipes 49 ) . At DO below the Pcrit the capacity of oxygen absorption and transport through the hemolymph is insufficient to meet basic metabolic demands, and the production of ATP must be supported via the anaerobic metabolism 43 . Nevertheless, the measured SMR might be reduced without compromising integrity, so the onset of anaerobic metabolism in response to decreasing DO could be delayed in comparison with decreases in oxygen consumption rates. Our results showed that at 21ºC the decrease in oxygen consumption below 6.7 kPa coincided with the onset of anaerobic metabolism since the apparent activity of LDH increased. LDH has been used repeatedly as an indicator of anaerobic potential specially in crustaceans where it is the only enzyme of the glycolytic pathway 50 , and it has been shown to respond to changes in DO levels within hours. However, this energy support can only be used over short periods of time, being unable to allow the permanence of an organism for prolonged periods in hypoxia 51 . Precisely, high temperature and low oxygen conditions would be avoided by most species throughout their life cycle. For juveniles kept at 11°C, no Pcrit was found in our experiments, since they showed an oxyregulatory behavior down to 1.4 kPa, also supported by the constant LDH apparent specific activity determined for starved organisms at 11°C across different oxygen concentrations. In this regard, these results are in agreement with observations of G. planipes in the northeastern Pacific 47 . Under natural conditions, many benthic juveniles of G. monodon can be found at concentrations below 0.7 mg O 2 L − 1 , and down to 0.2 mg O 2 L − 1 (~ 30–37°S) 13 , 14 in waters of about 11°C 52 . Postprandial metabolism in juveniles of G. monodon significantly depended on the temperature-DO interaction, that is, in general agreement with expected results 46 . Even though postprandial oxygen consumption results from several processes (mechanical digestion, absorption, assimilation), most of it is related to the latter 53 , in particular protein synthesis, and it can be interpreted as the cost of growth 54 . Therefore, the comparative analysis of postprandial metabolism (total energy expenditure) responses to different environmental conditions for organisms, in the same developmental stage and fed with the same type of food, can be related to the rates of protein synthesis 55 , 56 that will be used in all other metabolic activities 7 . In postprandial curve the total SDA depends both on the increment of oxygen consumption above the RMR as well as on its duration 46 . Invertebrates are expected to have a 2- to 3-fold increase in oxygen consumption over the routine metabolism 46 , that is congruent with results in normoxia at 11°C (SDA scope 2.63). But not at 21ºC, when the highest SDA peak observed, but only represented a 1.2 fold increase over RMR. In postprandial curve, increases of SDA peak with temperature are expected 46 , while the total oxygen consumption during the postprandial process might be conserved due to reductions in SDA duration at higher temperatures (within certain temperature range). In the present case, SDA time did not vary significantly between temperatures, so overall SDA energy was larger at higher temperature, but the overall SDA versus RMR expenditure was reduced in comparison with lower temperatures. The differences the SDA energy (in normoxia) between temperatures could be related to the early stage of development analyzed (juveniles), in fish it has been observed that the ability to compensate SDA expenditure with the increment of temperature is reached gradually during ontogeny 53 . Low DO conditions might impose a restriction in the peak of postprandial SDA (if the maximum oxygen uptake capacity was structurally limited) and therefore on SDA scope, as oxygen decreases, becoming a constraint to energy acquisition specially at high temperature 7 . In this case, the SDA scope increased with the decrease in temperature, and this trend continues with the decrease in DO. The decrease in the SDA scope at 11°C in the two low DO concentrations indicates that despite maintaining RMR stable at these oxygen conditions, juveniles do not sustain post-prandial normoxic oxygen uptake rates but maintained the overall SDA energy throughout hypoxic conditions. A key step for metabolic rules and evolution is the capacity of an organism to uptake and deliver of oxygen to tissues, cells and mitochondria 46 . The maximum delivery capacity of an organism via the routine rate could suggest limits to fitness in response to environmental conditions as usually evaluated for the scope for activity, growth but also SDA scope 58 . If that is the case, and the postprandial SDA peak would reflect such maximum uptake and delivery capacity to take advantage of external food sources, the length of time of postprandial activity, could compensate for the overall reduction of the upper limit of uptake, to meet a more stable level of energy SDA. Considering that the juvenile stage, when the organism is compelled to grow, the delivery hypothesis would not necessary be in agreement with the lack of compensation between high and low oxygen conditions for 11°C observed in this study. Because organisms do grow and are usually found in this conditions in the field at 30–37°S (< 0.7 mg O2 L − 1 and ~ 11°C, the adjustment of ATP demanding processes to varying temperatures and oxygen concentrations would provide a better argument to explain observed experimental results. Hypoxia at 21 C allowed for an increase over the SMR during postprandial metabolism, even below the Pcrit, except for the lowest level tested (Figs. 3 and 4 ). This is a common response in crustaceans within limited low-oxygen conditions below the Pcrit 48 . Within this environmental oxygen range, it should be the rate of internal (organ level) oxygen demand that sets the rate of whole organism oxygen uptake. Under severe hypoxia and higher temperature (0.7 mg DO and 21°C), G. monodon did not show a postprandial peak suggesting that at this high temperature, which enhances the basic demand for DO and low availability of DO (0.7 mg L − 1 ) the oxygen uptake rate is already at a maximum possible uptake rate, at the whole individual capacity. At 21°C and 0.7 mg L − 1 it would not be possible to digest and assimilate ingested food, and consequently the organisms must avoid these conditions. We expect that a plastic species such as G. monodon will not necessary restric its latitudinal distribution range in climate change scenarios but their vertical distribution and life cycle parameters. In scenarios of Climatic Change, it has been projected that OMZs would intensify (increase vertical, latitudinal and longitudinal extent) 59 , 60 , 8 . The trend shows that the SE Pacific is one of the areas that will be least affected by increasing deoxygenation 59 . Nevertheless, changes in oxygen patterns are expected to affect the vertical distribution of coastal aerobic species as a result of the shallower oxycline 60 . At the same time, the water column of the SE Pacific has tended to cool (-0.2°C) over the last decades, a trend that is partly explained by the intensification of the southern wind and large-scale changes in coastal circulation 61 , 62 , and possibly due to multidecadal oceanic-atmospheric oscillatory modes 63 . Global climate models suggest that temperature rise over the SE Pacific would be lower than in other ocean basins mainly due to wind-driven circulation. Nevertheless, the shallower position of the oxygen isopleth would connect the upper limit of the OMZ with higher temperatures, especially north of 24°S 60 . If this trend continues, two scenarios could be expected: (i) a reduction of the oxygenated area contracting the benthic habitat of G. monodon and anchovy in Peru, or (ii) an extension of the pelagic habitat to G. monodon to the south of 20°S. Latitudinal changes in habitat use of this species would have an ecosystemic effect, as this species is key to the trophic networks of both (benthic and pelagic) environments, including vertebrate and invertebrate species, some of which are of commercial importance (horse mackerel and hake). Based on our results we predict that in a scenario of surface cooling and expansion of hypoxic conditions, in species with a similar life history plasticity as documented here for G. monodon , the proportion of populations with pelagic life habits will increase. In contrast, for species without this plasticity, it can be expected that their populations will contract to areas that maintain favourable oxygen-temperature conditions. METHODS Bio-physical metadata compilation and analysis The latitudinal variability (meridional section) of mean temperature and dissolved oxygen concentrations over the continental shelf of western South America was characterized after extracting available temperature/oxygen profiles from the World Ocean Database (WOD, www.nodc.noaa.gov ) from 5°S to 35ºS and from the coast to offshore distances corresponding to station depths of 200 m. After checking the quality of temperature and DO values, they were averaged over time every 1º of latitude at standard depths. Afterwards the depths and temperature of limits of the OMZ were identified for each averaged profile, considering three values of oxygen isopleth 0.5, 1 and 2 ml O 2 L − 1 (Fig. 1 ). Finally, continental shelf width in km (distance from the coast to the 200 m isobaths) was estimated from the database GEBCO 2014 Grid, and also averaged for each degree of latitude. A database for G. monodon presence/absence was constructed after reviewing surveys conducted over the continental shelf of western South America (5°S − 37ºS) between 1965 and 2015 (Supplementary Table S1 online); 56 published papers and unpublished reports were used. The matrix of presence/absence of G. monodon in pelagic and benthic habitats for every degree of latitude was constructed using direct fisheries assessment reports of free-living individuals of this species as well as its presence in the diet of pelagic/demersal predators. Three types of life habits were distinguished by latitudinal degree: 1-benthic adults, 2-pelagic adults, and 3-both benthic and pelagic adults combined. A Random Forest analysis was utilized to relate the occurrence of the life habits of G. monodon (benthic, pelagic, and both combined) to a function of shelf width, depth limits of the OMZ (0.5, 1 and 2 ml O 2 L − 1 ), and temperature at the same oxygen levels throughout its distribution in the SE Pacific. Analyses were carried out using the library Random Forest 64 in Rstudio software (R Core Team, 2024) 65 . Ecophysiological experiments Juveniles of G. monodon were obtained from plankton, near Concepción Bay, southern Chile (36°28.4´S, 73°00.8´W) on March 19, 2014. Specimens were captured during the night, between 0–30 m, with a bongo net (300 µm), and immediately placed at 11°C-12°C to be transported to the Laboratory of Crustacean Ecophysiology (LECOFIC) at the Universidad Austral de Chile, Chile (Puerto Montt), where all the ecophysiological experiments were conducted. Before the experiments were set up, the collected juveniles were maintained in large aquaria with recirculating micro-filtered seawater, normoxia temperatures between 10°C-12°C, and they were fed every other day with Artemia spp. nauplii. The critical point (Pcrit) of standard oxygen consumption rate was determined through closed respirometry at two different temperatures (11°C and 21°C). For each temperature, individuals were incubated at eight starting dissolved oxygen (DO) levels (0.7, 1.4, 2.9 3.5, 4.5, 5.5, 6.5 and ~ 8 mg O 2, within the 1.5 to 24.3 kPa). First, juveniles were individually transferred to 1 L Schott bottles, and kept without feeding for 24 h in normoxia previous to the experiment. Experimental bottles were prepared with water at the desired temperature-DO initial conditions, the previously separated juveniles were introduced individually in these bottles one hour before measurements started. Oxygen concentration was determined at the start and after 5 hours of incubation. Six replicates and six controls (without juveniles) for each treatment were run. The DO treatments were achieved by bubbling seawater with N 2 gas. The temperature was maintained with a thermoregulated bath, where bottles were completely submerged. Initial and final DO were measured with an optic sensor, connected to Microx TX3AOT oxygen meter (PreSens, GmbH, Germany) and used to calculate oxygen consumption. After each experiments individuals were immediately weighted, frozen and stored at − 80°C until biochemical analyses. Postprandial metabolism (peak, time, scope and SDA, details in Supplementary Material) was determined at four DO levels (0.7, 1.4, 2.9 and ~ 8 mg O 2 L − 1 , equivalent to 0.5, 1, 2 ml L − 1 and normoxia, respectively) for three temperatures (11°C, 15°C, and 21°C). Individually reared juveniles remained fasting for 24h. They were then fed for 30 min with freshly hatched Artemia nauplii (~ 1500 nauplii/100 ml). Non-consumed nauplii were removed after the 30 min feeding period. Juveniles were contained in Schott bottles (100 ml) connected to an open system, where the input is connected to peristaltic pumps (maintaining constant flow: ~0.19 L h − 1 ) and the output connected to a Sensor Dish Reader SDR (PreSens, GmbH, Germany) of 24 sensor spot (DO log every 15 sec). Postprandial metabolism was measured for 24 h. The DO treatments were achieved by bubbling seawater with nitrogen, while the temperature was maintained by completely covering the bottles within a thermoregulated bath. The measurements were run for two oxygen concentrations and one temperature per day. Thereafter each individual was weighed and immediately frozen and stored at − 80°C until biochemical analyses. To characterize the postprandial metabolism, oxygen consumption curves were constructed (mg O 2 per g WW − 1 ) as a function of time, for each combined treatment of Temperature-DO. As described by Secor (2009) 66 , five descriptors of postprandial metabolism were extracted from each curve: (i) Standard metabolic rate (SMR), (ii) SDA Peak, (iii) SDA scope, (iv) total SDA (energy), and (v) SDA duration (time). Abdominal muscle (20 mg) of deep-frozen replicates of juvenils G. monodon from both experimental set-ups were separated for the determination of Lactate dehydrogenase apparent specific activity (LDH activity). The cephalotorax of juveniles (30 mg) frozen after postprandial experiments were used to determine Heat Shock Protein 70 (HSP70) and total protein concentrations, following Brokordt et al. (2015) 67 . All analyses were carried out using EPOCH microplate spectrophotometer (BioTeck). Ecophysiological data analysis All the analyses described below were conducted in R software (R Core Team, 2024). In order to calculate Pcrit, experimental DO were expressed in kPa. The mean between the initial and final DO concentration in each bottle was used as the reference for each respiration value. A regression analysis of oxygen consumption (mg O 2 h − 1 g − 1 ) as a function of oxygen concentration (kPa) was adjusted for each temperature. The regression was fitted with library ggplot2 (version 3.5.1 68 ), function geom_smooth and method “loess” (Local polynomial regression fitting). This allowed us to determine the breakpoint (Pcrit), represented by a change of slope in the response variable as a function of the independent variable. The same procedure was followed to relate LDH apparent specific activity and DO. The postprandial results were represented as mean ± standard deviation (library Rmisc, version 1.5 69 ). postprandial parameters, LDH activity and HSP70 concentration were compared between treatments (DO/temperature) using factorial two-way ANOVA, followed by a Tukey post-hoc test (HSD Tukey, library agricolae, version 1.2–4 70 ). Previously, normal distribution (Normal Q-Q plot) and homogeneity of variances (Levene’s test) were checked (library Car version 2.1–4 71 ). The figures were made with the library ggplot2 (version 3.5.1 68 ). Declarations Author Contribution M.A.G. and B.Y. developed the concept for this study. M.A.G., B.Y., M.R. and M.P., K.B. K.P. performed analysis. K. P. K.B., M.R., M.T., verified the analysis and provided data. M.A.G. and B.Y. wrote the original manuscript. M.A.G., M.R., M.P. and B.Y. designed the figures M.T. K.P. K.B commented on the results. All authors discussed and commented on the manuscript. Acknowledgement This study was funded by FONDECYT 1140831 (BY, MR, MT, KB, KP), FONDECYT 1140845 (MR), ANID “Becas Chile” Grant 21110922 (MAG), CLAP Project R20F0008 (MAG, MR, KB) and Anillo BiodUCCT ATE220044 (MAG, MP and MR). The authors thank the professionals Miguel Herrera, Juan Pablo Cumillaf, Andrea Martínez, and Lucas Clavel (LECOFIC Team, Universidad de Valdivia), Katherine Jeno and William Farías (Team FIGEMA, UCN). Dr. Leonardo Castro (UdeC) for facilitating the juvenils. Finally, we thank Lisa Levin (SCRIPS) for a critical review of the manuscript. Data Availability The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request. Supplementary information accompanies this paper Competing Interests: The authors declare that they have no competing interests. References Deutsch, C., Ferrel, A., Seibel, B., Pörtner, H. O. & Huey, R. B. Constraint on Marine Habitats. Science 348 (6239), 1132–1136 (2015). Levin, L. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6198822","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":450570391,"identity":"4e0e2e3f-cfe3-49c5-ab40-2792d74be56d","order_by":0,"name":"María de los Ángeles Gallardo","email":"","orcid":"","institution":"Universidad Católica del Norte","correspondingAuthor":false,"prefix":"","firstName":"María","middleName":"de los Ángeles","lastName":"Gallardo","suffix":""},{"id":450570392,"identity":"3d373520-36da-4183-bb6b-0db5d7368666","order_by":1,"name":"Kurt Paschke","email":"","orcid":"","institution":"Universidad Austral","correspondingAuthor":false,"prefix":"","firstName":"Kurt","middleName":"","lastName":"Paschke","suffix":""},{"id":450570393,"identity":"6ae74e02-b6e1-4190-95fb-a665ac869507","order_by":2,"name":"Katherina Brokordt","email":"","orcid":"","institution":"Universidad Católica del Norte","correspondingAuthor":false,"prefix":"","firstName":"Katherina","middleName":"","lastName":"Brokordt","suffix":""},{"id":450570394,"identity":"75e3ee36-baba-4d67-a795-b1112c5079eb","order_by":3,"name":"Marcel Ramos","email":"","orcid":"","institution":"Universidad Católica del Norte","correspondingAuthor":false,"prefix":"","firstName":"Marcel","middleName":"","lastName":"Ramos","suffix":""},{"id":450570395,"identity":"beb8da30-e206-478f-9e63-83ea150dc1a8","order_by":4,"name":"Martin Thiel","email":"","orcid":"","institution":"Universidad Católica del Norte","correspondingAuthor":false,"prefix":"","firstName":"Martin","middleName":"","lastName":"Thiel","suffix":""},{"id":450570396,"identity":"2d66d152-2750-4dff-8cac-95f7ec0a21aa","order_by":5,"name":"Matias Pizarro-Koch","email":"","orcid":"","institution":"Universidad de Valparaiso","correspondingAuthor":false,"prefix":"","firstName":"Matias","middleName":"","lastName":"Pizarro-Koch","suffix":""},{"id":450570397,"identity":"f1211acb-9b1e-428e-ad78-aca666c8badd","order_by":6,"name":"Beatriz Yannicelli","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAxklEQVRIiWNgGAWjYBACAxjJD6ITCkjRItkA0mJAtBYQ4wAKFw8wl0h+9rigwE7O+PzqxA8PDBjk+cUO4NdiOSPN3HiGQbKx2Y23myWADjOcOTuBgMNuJJhJ8xgcSNx24+wGkJYEg9sEtaR/A2mp3zzj7OYfRGrJAduSYMDfu404Wyx73pQBtSQbzrjBu80iwUCCsF/M2dO3SfP8sZPn7z+7+eaPCht5fmkCWhgEYAokwAwJAspBgP8AOmMUjIJRMApGARoAAJFZQW7CdPmuAAAAAElFTkSuQmCC","orcid":"","institution":"Universidad de la República","correspondingAuthor":true,"prefix":"","firstName":"Beatriz","middleName":"","lastName":"Yannicelli","suffix":""}],"badges":[],"createdAt":"2025-03-10 23:08:10","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6198822/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6198822/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41598-025-25984-4","type":"published","date":"2025-11-21T15:58:57+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":82001315,"identity":"1c556da0-e875-4f78-baa3-0cfc97eeb6e5","added_by":"auto","created_at":"2025-05-05 19:51:21","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":996908,"visible":true,"origin":"","legend":"\u003cp\u003eArea of study and latitudinal variation of the variables used in the prediction of change habitat use of \u003cem\u003eGrimothea monodon\u003c/em\u003e. A) Area of study (5°S to 38°S). The figures B, C and D represent the mean for each variable generated at intervals of 1º of latitude. B) Shelf width (km). C) Latitudinal variation of the temperatures associated with the OMZ limits (2, 1 and 0.5 ml L\u003csup\u003e-1\u003c/sup\u003e). D) Latitudinal variation of vertical position (depth m) of the limits of the OMZ (2, 1 and 0.5 ml L\u003csup\u003e-1\u003c/sup\u003e). E) Temperature/oxygen observed to the 15°S (blue), 22°S (black) and 37°S (red).\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6198822/v1/78f7747d895d3c6b60fd550d.jpeg"},{"id":82001318,"identity":"09025bd9-4706-4431-932e-511959587de8","added_by":"auto","created_at":"2025-05-05 19:51:21","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":773238,"visible":true,"origin":"","legend":"\u003cp\u003eRelationship between presence and absence of pelagic and benthic morphs of adults of \u003cem\u003eGrimothea monodon,\u003c/em\u003e with respect to the latitudinal oceanographic characterization between the 5°S and 35°S. a) Latitudinal climatology of the temperature (°C). b) Latitudinal climatology of the oxygen concentration (ml L\u003csup\u003e-1\u003c/sup\u003e). c) Presence / absence of pelagic and benthic habitat in its southern latitudinal distribution. Circles completely filled in grey indicate presence of adults and open circles indicate absence of adults of \u003cem\u003eG. monodon\u003c/em\u003e. Size of the circles represents the difference of abundance or biomass reported (small circles: individuals m\u003csup\u003e-2\u003c/sup\u003e, large circles: tons). Source a) and, b): WOD, source c): published papers, unpublished thesis and fisheries direct and indirect surveys (Supplementary Table SI online).\u003c/p\u003e","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6198822/v1/f551df9ab5595db125c566a9.jpeg"},{"id":82000648,"identity":"ce7135eb-8c9d-413b-a76f-b302984d31de","added_by":"auto","created_at":"2025-05-05 19:35:21","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":103852,"visible":true,"origin":"","legend":"\u003cp\u003ePhysiological response of \u003cem\u003eGrimothea monodon\u003c/em\u003e juveniles exposed to different oxygen partial pressure and two temperatures (11°C in grey and 21°C in black). A) Oxygen consumption expressed as mg O2 h\u003csup\u003e-1\u003c/sup\u003e g\u003csup\u003e-1\u003c/sup\u003e and vertical dashed line indicates the Pcrit for the 21°C curve. B) Lactate dehydrogenase activity expressed as LDH UI g\u003csup\u003e-1\u003c/sup\u003e. The black lines represent adjusting a regression analysis to oxygen consumption (mg O2 h\u003csup\u003e-1\u003c/sup\u003e g\u003csup\u003e-1\u003c/sup\u003e) as a function of oxygen concentration. The regression was fitted with the method “loess” (Local polynomial regression fitting). This allowed us to determine the breakpoint (Pcrit), represented by a change of slope in the response variable as a function of the independent variable.\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-6198822/v1/f45257c5feb25c10e8a8643b.png"},{"id":82000649,"identity":"4b6e394d-7c16-4ce7-8d83-0905b7f9894e","added_by":"auto","created_at":"2025-05-05 19:35:21","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":517315,"visible":true,"origin":"","legend":"\u003cp\u003eVariables of feeding response in juveniles of \u003cem\u003eGrimothea monodon\u003c/em\u003e characteristics of postprandial metabolism. A) SMR standard metabolic rate, mean metabolic rate at postabsortive and rest. B) Peak SDA, mean postprandial peak in metabolism. Produced by the increase of oxygen consumption in response to feeding. C) SDA scope, Index corresponding to Peak SDA divides by SMR. D) SDA duration, time from feeding to SMR. E) SDA (specific dynamic action), accumulated energy expended above SMR for duration SDA response. Different letters denote treatment significantly different from each other (Tukey HSD, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.05; Supplementary Table S3 online).\u003c/p\u003e","description":"","filename":"floatimage5.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6198822/v1/1e85751718e6cbbe6b445988.jpeg"},{"id":82000668,"identity":"5fa8588e-572c-4095-99f1-698b0dd5f714","added_by":"auto","created_at":"2025-05-05 19:35:23","extension":"jpeg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":283693,"visible":true,"origin":"","legend":"\u003cp\u003eEnzyme activity at the end postprandial metabolism in juveniles of \u003cem\u003eGrimothea monodon \u003c/em\u003eA) Mean lactate dehydrogenase (LDH) activity and B) mean HSP70 finalized the postprandial metabolism for the different treatments of temperature and oxygen. Different letters denote treatment significantly different from each other (Tukey HSD, \u003cem\u003ep\u003c/em\u003e\u0026lt; 0.05; Supplementary Table S3 online).\u003c/p\u003e","description":"","filename":"floatimage7.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6198822/v1/ab1d670a5005827eb88d19eb.jpeg"},{"id":96650226,"identity":"e195af33-ef25-42a9-ae15-f0266e79193a","added_by":"auto","created_at":"2025-11-24 16:10:04","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3474154,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6198822/v1/7aef7350-e411-41a7-8962-26aaab4d9212.pdf"},{"id":82001928,"identity":"a4d94859-361f-408f-9c8a-ef3b178d2db5","added_by":"auto","created_at":"2025-05-05 20:07:21","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":852448,"visible":true,"origin":"","legend":"","description":"","filename":"GallardoetalSI.25425R.docx","url":"https://assets-eu.researchsquare.com/files/rs-6198822/v1/bd9c89b18ec85f369df6299b.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Squat lobster latitudinal life habitat shifts and metabolic response to combined temperature and oxygen conditions in the Humboldt Current System","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eChanges in oxygen availability and thermal conditions represent challenges that marine species must overcome in the face of global climate change scenarios\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e. Ocean oxygen depletion and temperature rise are expected to restrict the suitable habitat of marine invertebrates in the near future\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e due to their metabolic thresholds\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e. Responses at individual/ population level growth and reproduction as well as species biogeographical distributions are expected\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e. The effects of temperature and oxygen on the physiology of ectotherm organisms have been studied mainly in species inhabiting coastal environments\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e, but are scarce in organisms inhabiting oxygen minimum zones (OMZ)\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e that already display complex physiological adaptations to overcome oxygen-poor, but mainly cold conditions\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e. Few species are reported having a geographic distribution extending across hypoxic conditions (as prevailing in OMZs) and pronounced temperature gradients. A methodological approach to infer the future shifts of OMZs on population parameters and distribution is to evaluate the current distribution and life cycle characteristics of species that occupy contrasting temperature and oxygen conditions together with their ecophysiological and metabolic characteristics. This approach should allow to evaluate novel expected responses to future environmental physicochemical conditions for these type of organism.\u003c/p\u003e \u003cp\u003eHypoxia may affect routine metabolic rates and aerobic scope, of metazoan organisms (within species-specific tolerance thresholds), limiting the supply of cellular oxygen and ultimately affecting the production of energy (ATP) by aerobic metabolic pathways\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e. OMZ organisms usually keep oxygen provision independent from ambient concentrations down to very low levels (oxyregulation)\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e. Nevertheless, routine metabolic demands increase with temperature thus i) rising the oxygen tension below which oxyregulation no longer takes place (critical points Pcrit) and ii) reducing aerobic scope (organism capacity to uptake oxygen above routine metabolic rate RMR), an indicator of aerobic performance and individual fitness\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e. Therefore, temperature variability associated with the upper OMZ boundary (0.5-2.0 ml O\u003csub\u003e2\u003c/sub\u003e L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) is expected to have strong metabolic and biological effects on organisms\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e as shown for temperature/oxygen modulation of individual fish performance\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003e \u003cem\u003eGrimothea monodon\u003c/em\u003e (H. Milne Edwards, 1837), a decapod crustacean (Munididae) widely quoted in the literature as \u003cem\u003ePleuroncodes monodon\u003c/em\u003e until the recent reconsideration of its taxonomic status\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e, is distributed along the Pacific coast of America, from ~\u0026thinsp;15\u0026deg;N to ~\u0026thinsp;40\u0026deg;S\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e. Its capacity to withstand low oxygen concentrations have been proven from field campaigns\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e,\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e and laboratory experiments, although severe hypoxia exerts metabolic, physiological and behavioural sublethal effects\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e,\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e. Thus, it can be considered an ideal model species to examine its response to latitudinal sections of temperature and oxygen concentration within its distribution range. Between Peru and Chile, the OMZ becomes narrower, thinner and deepens with latitude\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e while sea surface temperature diminishes (\u0026gt;\u0026thinsp;23\u0026deg;C to 12\u0026deg;C)\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e. At ~\u0026thinsp;7\u0026deg;S for example, large pelagic populations of the species occupy surface waters above the oxycline during day and night hours\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e,\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e, south of 25\u0026deg;S adults sustain an important benthic trawling fishery on the poorly oxygenated continental shelf (e.g. ~34\u0026ndash;37\u0026deg;S)\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e, and limited observations show adult vertical migration are plausible in Peruvian margins\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe high phenotypic plasticity of \u003cem\u003eGrimothea monodon\u003c/em\u003e\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e have also an expression on the smaller adult and size at maturity in northern pelagic populations\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e,\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e compared to southern benthic ones. Life in benthic habitats is attained in southern populations after a juvenile stage that migrates daily from surface waters to the benthos\u003csup\u003e\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e, and to the best of our knowledge there are no reports of pelagic ovigerous females in these southern latitudes. So far, a qualitative literature review points to both temperature and hypoxia among the potential drivers of shifting plastic habits of the species\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e, nevertheless neither the upper OMZ-temperature association with latitude over the continental shelf of the Humboldt Current System (HCS) has been described yet, nor its quantitative relationship with the species life habitats. The physiological and ecological restrictions that the juveniles would confront developing as vertical migrators from warm oxygenated waters to deep colder hypoxic waters. could be key determinants of the later habits and adult population parameters.\u003c/p\u003e \u003cp\u003eWe hypothesize that the prevalent adult life habit segregation (pelagic/benthic) within the 5\u0026deg;S to 35\u0026deg;S latitudinal range of our study (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eA). is associated with the latitudinal variability of temperature-oxygen oceanographic conditions over the continental shelf that varies between 10 to 100 km width (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eB). Also, naturally occurring combinations of temperature-oxygen levels within this distribution range impose metabolic constraints on juveniles. In order to evaluate our hypothesis, we first reconstructed the mean latitudinal distribution of water temperature and oxygen characteristics over the continental shelf. Second, we conducted an exhaustive review on the occurrence of pelagic/benthic \u003cem\u003eG. monodon\u003c/em\u003e throughout the same latitudinal range. Third, we related the presence/absence of each life habit (pelagic or benthic) with the latitudinal oceanographic reconstruction. Finally, we experimentally determined metabolic responses of juveniles to combined temperature and dissolved oxygen (DO) conditions within natural ranges on routine and post-prandial metabolic rates (specific dynamic action, SDA) and metabolic enzyme activities.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"RESULTS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eLatitudinal oceanography\u003c/h2\u003e \u003cp\u003eBased on World Ocean Database (WOD) oceanographic profiles (1969\u0026ndash;2008) for the Eastern South Pacific (ESP) continental shelf (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eA, B), hypoxic waters are colder than more oxygenated surface waters. The mean temperature associated with the OMZ limits (as 2, 1, and 0.5 ml L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e oxygen isopleth) decreased with latitude (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eC). At 14\u0026ndash;16\u0026deg;S, the temperature were 16\u0026deg;C, 14.9\u0026deg;C and 14.1\u0026deg;C, respectively, while they descended to 12.3\u0026deg;C, 12.1\u0026deg;C and 11.8\u0026deg;C between 23\u0026ndash;37\u0026deg;S, for each oxygen isopleth. Isopleths depth do not trend monotonically over the continental shelf (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eD) and in general low oxygen waters (below 1 ml L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) also showed a decrease in temperature with latitude: 15\u0026deg;S 12\u0026ndash;18\u0026deg;C, 22\u0026deg;S 12\u0026ndash;14\u0026deg;C and 35\u0026deg;S 10-11.5\u0026deg;C (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eE). Although less marked, the pattern can even be observed on sections from the gridded World Ocean Atlas (WOA), that include offshore conditions (Supplementary Fig. \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e online). Mean surface temperatures over the continental shelf range from ~\u0026thinsp;11\u0026ordm;C in the subtropical region (35\u0026ndash;37\u0026deg;S) to ~\u0026thinsp;20\u0026ordm;C in the northern HCS (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eE, \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eA) and the largest latitudinal surface temperature gradient was observed between 27\u0026deg;S and 20\u0026ordm;S. Vertical temperature profiles and temperature at isopleth display a wider range in northern latitudes. The 2 ml L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e oxygen isopleth deepened south of 18\u0026deg;S from 15m to 50m, while the 1 and 0.5 ml L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e also deepened north of 8\u0026deg;S (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eD, \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eB). The depth of the 0.5 ml L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e oxygen isopleth followed neither a monotonic trend with latitude nor shelf width latitudinal variability (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eB, D, Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eB).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003ePresence/absence of\u003c/b\u003e \u003cb\u003eGrimothea monodon\u003c/b\u003e \u003cb\u003ein pelagic and benthic zones\u003c/b\u003e:\u003c/p\u003e \u003cp\u003eThe latitudinal distribution of \u003cem\u003eG. monodon\u003c/em\u003e adult habitat shows a break between 20\u0026deg;S and 23\u0026deg;S (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eC). Out of 37 demersal/benthic studies between 1965 and 2015 between 5\u0026deg;S and 38\u0026deg;S (Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e), 16 studies reported benthic \u003cem\u003eG. monodon\u003c/em\u003e systematically north of 9\u0026deg;S and south of 20\u0026deg;S-23\u0026deg;S (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eC). North of 9\u0026deg;S, benthic \u003cem\u003eG. monodon\u003c/em\u003e appeared between 1996 and 2014 at low densities (Supplementary Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e online) as bycatch and food item of Peruvian hake\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e. South of 20\u0026deg;S-23\u0026deg;S, \u003cem\u003eG. monodon\u003c/em\u003e sustains large benthic biomasses, (targeted by trawling fishery; bycatch and food item of Chilean hake\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e). Benthic densities in Chile have been one to two orders of magnitude higher than those ever recorded in Peru.\u003c/p\u003e \u003cp\u003eImportant biomasses of pelagic (adult) \u003cem\u003eG. monodon\u003c/em\u003e have been revealed during small pelagic fish assessments between 6\u0026deg;S and 18\u0026deg;S, overlapping with the \u003cem\u003eEngraulis ringen\u003c/em\u003es distribution over the Peruvian continental shelf from 1988 onwards\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e. North of 9\u0026deg;S, benthic and pelagic forms coexist. In Chile, \u003cem\u003eG. monodon\u003c/em\u003e small pelagic assessments have revealed \u003cem\u003eG. monodon\u003c/em\u003e pelagic forms only between 20\u0026deg;S and 18\u0026deg;S, as anchovy bycatch\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e, but never south of those latitudes even though such assessments extend to 40\u0026deg;S (Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe Peruvian Institute of the Sea (IMARPE) undertook campaigns (1970\u0026ndash;1972) from 12\u0026deg;S to 18\u0026deg;S dedicated to explore potential fisheries of benthic crustaceans. \u003cem\u003eG. monodon\u003c/em\u003e was found at a single 40 m depth station, 16.5\u0026deg;S during 1972 (El Ni\u0026ntilde;o) at low densities (Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e). Two records of benthic \u003cem\u003eG. monodon\u003c/em\u003e were found at 12.2\u0026deg;S: i) Seven individuals caught at 160 m depth during 1965 (El Ni\u0026ntilde;o)\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e and ii) 11 individuals at 71 and 145 m depth in 2013, neutral conditions\u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/span\u003e\u003c/sup\u003e, and hypoxic waters\u0026thinsp;~\u0026thinsp;1 ml L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eTemperatures associated with the limits of the OMZ as 0.5, 1 or 2 ml L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e oxygen isopleth as well as oxygen isopleth depths significantly explained the shift in \u003cem\u003eG. monodon\u003c/em\u003e habitat use, accounting for 90% of the variance (Random Forest analysis, Supplementary Table S2 online). The first model fitted including all the predictor variables, explained 90.9% (Pseudo-R\u003csup\u003e2\u003c/sup\u003e) of the variance. The exclusion of variables of lower \u0026ldquo;Mean Decrease Accuracy\u0026rdquo; (shelf width and depth of 0.5 ml L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e oxygen isopleth), improved variance explanation to 93.9%. The models break down the probability of predicting each scenario, both models had 100% accuracy in predicting benthic habitat as low temperatures associated to the limits of the OMZ (\u0026lt;\u0026thinsp;12.3\u0026deg;C) and deeper location of the OMZ limit (\u0026gt;\u0026thinsp;50 m). The prediction of pelagic habit had a success rate of 91.7%: when the limits of OMZ (2 and 1 ml L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) are associated with high temperatures (\u0026gt;\u0026thinsp;15\u0026deg;C) and shallow location (\u0026lt;\u0026thinsp;50 m). The prediction of co-occurrence of benthic and pelagic habits had an accuracy of 66.7%. The presence of co-occurrence is related to the deepening of the limits of 1 and 0.5 ml L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e under 90 m and a wide shelf (\u0026gt;\u0026thinsp;50 km) (Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cb\u003eEcophysiology of\u003c/b\u003e \u003cb\u003eGrimothea monodon\u003c/b\u003e\u003c/p\u003e \u003cp\u003eMetabolic rates of \u003cem\u003eG. monodon\u003c/em\u003e juveniles were significantly affected by temperature, oxygen concentration and their interaction in both fasting and fed conditions. The routine metabolic rate (RMR) of \u003cem\u003eG. monodon\u003c/em\u003e juveniles increased with temperature, almost tripling oxygen consumption from 11\u0026deg;C to 21\u0026deg;C in normoxia (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eA). At 11\u0026deg;C, juveniles metabolic rate was low (mean\u0026thinsp;=\u0026thinsp;0.13\u0026thinsp;\u0026plusmn;\u0026thinsp;0.03 mg O\u003csub\u003e2\u003c/sub\u003e h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) and independent of DO condition within the DO range evaluated (Pcrit at 11\u0026deg;C below our lowest condition, \u0026lt;\u0026thinsp;1.4 kPa; 0.6 mgO\u003csub\u003e2\u003c/sub\u003e L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e). At 21\u0026deg;C oxyregulatory response was observed down to a Pcrit of 7 kPa (2.5 mg O\u003csub\u003e2\u003c/sub\u003e L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e). Oxygen consumption decreased from a mean of 0.32\u0026thinsp;\u0026plusmn;\u0026thinsp;0.07 mg O\u003csub\u003e2\u003c/sub\u003e h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (above the Pcrit) to 0.23\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05 mg O\u003csub\u003e2\u003c/sub\u003e h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at the lowest oxygen concentration analyzed (\u0026gt;\u0026thinsp;1.4 kPa), a 60.3% of the SMR (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eA). The breaking point was significant.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe apparent specific activity of LDH (Lactate dehydrogenase) in juveniles of \u003cem\u003eG. monodon\u003c/em\u003e was higher with increasing temperature and hypoxia. LDH activity remained relatively stable in juveniles kept at 11\u0026deg;C (mean\u0026thinsp;=\u0026thinsp;4.45\u0026thinsp;\u0026plusmn;\u0026thinsp;1.06 UI LDH g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), throughout the range of DO analyzed. At 21\u0026deg;C the apparent specific activity of LDH increased from 5.22 (above the Pcrit) to 7.23 UI LDH g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, at the lowest oxygen level considered (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eB).\u003c/p\u003e \u003cp\u003eTemperature significantly affected RMR in postprandial metabolic experiments depending on oxygen concentrations. RMR increased with temperature at normoxia and at 2.9 mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, but at 1.4 and 0.7 mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e the maximum SMR occurred at 15\u0026deg;C (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eA, Supplementary Table S3 online). Consistent with previous experiments, at 11\u0026deg;C juveniles maintained their SMR throughout the DO levels analyzed (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eA and \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eA). At 21\u0026deg;C SMR decreased with decreasing DO; the reduction from normoxia to 2.9 mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e was similar to the previous experiments and was further reduced at 0.7 and 1.4 mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, although consumption did not differ significantly between the latter (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eA). At 15\u0026deg;C, SMR in normoxia was higher only in comparison with the lowest oxygen treatment (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eA, Supplementary Table S3 online). The peak of the postprandial metabolic curve was modulated by temperature and DO (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eB). Overall it decreased with decreasing oxygen concentrations at all temperatures but differing slopes/shapes. The decrease was steeper at 21\u0026ordm;C than at 15\u0026deg;C and 11\u0026deg;C; no peak was measured at 0.7 mgL\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for 21\u0026deg;C. At 11\u0026ordm;C, the difference was only significant between normoxia-2.9 and 1.4\u0026ndash;0.7 mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e treatments. Only in normoxia postprandial peak increased with temperature. In general, the postprandial metabolic scope increased with oxygen concentration for all temperatures, and it was higher for low temperatures regardless of the DO treatment (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eC, Supplementary Table S3 online).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe postprandial metabolic duration decreased with decreasing oxygen concentrations and the decline was steeper at higher temperatures. At 11\u0026deg;C and 15\u0026ordm;C, it decreased from normoxia to 2.9 mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e remaining constant in the other oxygen treatments, while at 21\u0026ordm;C, it decreased through all hypoxia treatments. In normoxia, postprandial metabolic duration was marginally longer at 21\u0026deg;C, while in hypoxia (0.7 and 1.4 mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) the time decreased significantly with increasing temperature (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eD).\u003c/p\u003e \u003cp\u003eIn normoxia, the accumulated energy expended during the postprandial metabolic response was related significantly with temperature and oxygen. The accumulated energy SDA decreased 85 to 90% from normoxia to 2.9 mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for all temperatures. The decrease below 2.9 mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e was steepest at 21\u0026deg;C, reaching 0 al 0.7 mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, and it was not significant for 15\u0026deg;C and 11\u0026ordm;C. Under hypoxia, there were no significant differences between temperatures (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eE; Supplementary Table S3 online).\u003c/p\u003e \u003cp\u003eFor LDH activity a significant effect of both temperature (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001) and DO concentration (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.007) was observed. At 21\u0026deg;C, LDH activity remained constant and low (~\u0026thinsp;3 UI g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) throughout different DO concentrations. At 15\u0026deg;C, LDH activity only increased at 0.7 mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (mean 9.3 UI g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), while at 11\u0026deg;C, high LDH activities were observed from 2.9 mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e to the lower DO concentrations evaluated. Overall, LDH activity decreased with temperature (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eA). The concentration of HSP70 was significantly affect by DO (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.0143) but not by temperature (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.67). The highest concentration of HSP70 was found at 0.7 mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (mean\u0026thinsp;=\u0026thinsp;1.3 HSP70 mg protein\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eB).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eThe shallow depth of the oxycline had previously been viewed as the main cause for the shift of adult \u003cem\u003eGrimothea monodon\u003c/em\u003e\u003csup\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e from benthic habitats in southern-central Chile to pelagic habits in southern Peru. Nevertheless, why low-oxygen levels were avoided at low latitudes while at higher latitudes they inhabited hypoxic bottom waters remained open. Our study shows that the most conspicuous adult habitat shift was related with the temperature of the upper OMZ as well as its depth, so warm hypoxic waters seem to restrict \u003cem\u003eG. monodon\u003c/em\u003e above oxygen isopleth (2 ml O\u003csub\u003e2\u003c/sub\u003e L\u003csup\u003e\u0026minus;\u003c/sup\u003e1). We also show that juvenile stages might be metabolically restricted by hypoxia at realistic warm temperatures, as evidenced by the significant decreases in SDA (accumulated energy) in those conditions. Juveniles are known to migrate daily between surface oxygenated and cold hypoxic demersal waters in northern-central and southern-central Chile\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e,\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e. Resting metabolic rates show no decrease with low oxygen concentrations at 11\u0026deg;C but they do at 15\u0026deg;C and especially at 21\u0026deg;C and postprandial metabolism is restricted under warm hypoxic conditions. Thus, the constraints that squat lobsters start experiencing during the juvenile phase might dictate their future life habit (benthic or pelagic) and the observed latitudinal shift in habitat use.\u003c/p\u003e \u003cp\u003eThroughout the latitudinal range considered, oxygen concentrations below 1 ml L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 0.5 ml L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e were frequent in subsurface waters over the continental shelf. The upper limit of the OMZ has been described to deepen with latitude and is generally assumed to reach depths larger than 100 m towards 37\u0026ordm;S \u003csup\u003e\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e,\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e\u003c/sup\u003e. Nevertheless, when only oxygen profiles above the continental shelf (\u0026lt;\u0026thinsp;200 m) are evaluated, the presence of a shallower OMZ becomes evident throughout the Chilean continental shelf, as described for the Concepci\u0026oacute;n area\u003csup\u003e\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u003c/sup\u003e. Low oxygen conditions are usually associated with \"cold\" waters \u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e, but the latitudinal variability of \"cold\" conditions had not previously been analyzed, despite of the known interactive effect of temperature and oxygen concentration on the metabolism of ectothermic species\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e and its overall importance for all metabolic and geochemical processes. The latitudinal difference of temperature for the OMZ upper limit can vary between 4\u0026ndash;7\u0026deg;C and the thermal gradient across the oxycline varies from 2\u0026deg;C in the south to 6\u0026deg;C at low latitudes (Supplementary Fig. S2 online).\u003c/p\u003e \u003cp\u003eOur review revealed that thermal and oxygen latitudinal variations were significantly associated with changes in adult life habits. Several members of the family Munididae are characterized by bentho-pelagic habits with (\u003cem\u003eGrimothea gregaria\u003c/em\u003e)\u003csup\u003e\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e,\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e\u003c/sup\u003e or without (\u003cem\u003eG planipes\u003c/em\u003e\u003csup\u003e\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e\u003c/sup\u003e and \u003cem\u003eG quadrispina\u003c/em\u003e\u003csup\u003e\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e\u003c/sup\u003e) significant differences in morphology between pelagic and benthic adult morphologies, but significant larger sizes in benthic environments. In the case of \u003cem\u003eG. monodon\u003c/em\u003e, the use of different habitats was explained by the variability of the structure of temperature/oxygen profiles with latitude (R\u0026thinsp;=\u0026thinsp;90.9), whereas changes in life history (longevity, maximum size, and first sexual maturity) may respond to latitudinal variability of temperature (Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). In Peru adult pelagic squat lobsters are captured at temperatures between 16\u0026deg;C and 23\u0026deg;C\u003csup\u003e\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e\u003c/sup\u003e, while in Chile they are caught in the benthos at 11\u0026deg;C-12\u0026deg;C\u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e ). The size (CL\u0026ndash;Carapace Length) at sexual maturity differs by ~\u0026thinsp;6\u0026ndash;8 mm between pelagic (Peru, CL 10 mm) and benthic (Concepci\u0026oacute;n, Chile, CL\u0026thinsp;\u0026gt;\u0026thinsp;18 mm) individuals\u003csup\u003e\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e,\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e\u003c/sup\u003e. Our observations do not contradict the expected temperature-size relationship characteristic of ectotherm taxa\u003csup\u003e\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e,\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e\u003c/sup\u003e. Temperature also show a direct relationship between longevity and size at first sexual maturity, as well as maximum adult size since the dependence of development on temperature is steeper than that of growth.\u003c/p\u003e \u003cp\u003eMeeting the oxygen requirements necessary to support the expected increase on metabolic rates (RMR, postprandial metabolism) from 11\u0026deg;C to 15\u0026ndash;18\u0026ordm;C is restricted for juveniles at the oxygen concentration typical of the upper OMZ. In addition, the increase in temperature affects the solubility of oxygen, which is why under hypoxic conditions the availability of oxygen is expected to be reduced in warm conditions \u003csup\u003e\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e\u003c/sup\u003e. Together warm hypoxic conditions would restrict both habitat suitability and attainable size\u003csup\u003e\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eFurther support for the temperature \u0026amp; oxygen isopleth habitat restriction explanation, is provided by the systematic observation of \u003cem\u003eG. monodon\u003c/em\u003e benthic adults between 6\u0026deg;S and 7\u0026deg;S and their eventual presence at 11\u0026deg;S and 16\u0026deg;S\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e,\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e. Between 6\u0026deg;S and 7\u0026deg;S, the OMZ deepens due to intrusion of the Cromwell current (high in oxygen and nutrients)\u003csup\u003e\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e\u003c/sup\u003e, whereas the few benthic individuals recorded at 11\u0026deg;S, 12\u0026deg;S and 16\u0026deg;S were collected during ENSO warm years (2002, 1967, 1972 respectively), when the OMZ retreats offshore to deeper depths. In both scenarios the condition of a shallow-warm oxygen isopleth are broken.\u003c/p\u003e \u003cp\u003eThe results of RMR, Pcrit and postprandial experiments in the different realistic scenarios of temperature/DO evaluated were in agreement with the field observations on habitat use and plasticity with latitude. As expected, an interactive effect of temperature and oxygen concentration was observed on metabolic rates of \u003cem\u003eG. monodon\u003c/em\u003e juveniles. First RMR increased with temperature between 11\u0026deg;S and 21\u0026deg;C, the temperature range inhabited by natural populations in normoxia. The Pcrit for RMR was detected at high temperatures (6.7 kPa), but not at 11\u0026deg;C (within the range of kPa evaluated) in \u003cem\u003eG. monodon\u003c/em\u003e juveniles, regardless of feeding condition (starvation vs post-prandial measurements). RMR values for \u003cem\u003eG. monodon\u003c/em\u003e juveniles are in agreement with those expected from the log (weight specific respiration rate) to log (individual weight) relationship through the species life cycle (Supplementary Fig. \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e online) also described for other crustaceans\u003csup\u003e\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e\u003c/sup\u003e, as well with those reported for the same species\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e. In \u003cem\u003eG. planipes\u003c/em\u003e Pcrit was detected at 0.1 mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (0.24 kPa at 10\u0026deg;C\u003csup\u003e\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e\u003c/sup\u003e, and 0.5 kPa at 13\u0026deg;C \u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e). This is coincident with expected results for ectotherms that within species-specific ranges show higher RMR as well as Pcrit at higher temperatures\u003csup\u003e\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e\u003c/sup\u003e, and also with observations of other squat lobster species, such as \u003cem\u003eGalathea strigose\u003c/em\u003e\u003csup\u003e\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e\u003c/sup\u003e and adult \u003cem\u003eGrimothea planipes\u003c/em\u003e (ex \u003cem\u003ePleuroncodes planipes\u003c/em\u003e\u003csup\u003e\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e\u003c/sup\u003e) .\u003c/p\u003e \u003cp\u003eAt DO below the Pcrit the capacity of oxygen absorption and transport through the hemolymph is insufficient to meet basic metabolic demands, and the production of ATP must be supported via the anaerobic metabolism\u003csup\u003e\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e\u003c/sup\u003e. Nevertheless, the measured SMR might be reduced without compromising integrity, so the onset of anaerobic metabolism in response to decreasing DO could be delayed in comparison with decreases in oxygen consumption rates. Our results showed that at 21\u0026ordm;C the decrease in oxygen consumption below 6.7 kPa coincided with the onset of anaerobic metabolism since the apparent activity of LDH increased. LDH has been used repeatedly as an indicator of anaerobic potential specially in crustaceans where it is the only enzyme of the glycolytic pathway\u003csup\u003e\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e\u003c/sup\u003e, and it has been shown to respond to changes in DO levels within hours. However, this energy support can only be used over short periods of time, being unable to allow the permanence of an organism for prolonged periods in hypoxia\u003csup\u003e\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e\u003c/sup\u003e. Precisely, high temperature and low oxygen conditions would be avoided by most species throughout their life cycle.\u003c/p\u003e \u003cp\u003eFor juveniles kept at 11\u0026deg;C, no Pcrit was found in our experiments, since they showed an oxyregulatory behavior down to 1.4 kPa, also supported by the constant LDH apparent specific activity determined for starved organisms at 11\u0026deg;C across different oxygen concentrations. In this regard, these results are in agreement with observations of \u003cem\u003eG. planipes\u003c/em\u003e in the northeastern Pacific\u003csup\u003e\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e\u003c/sup\u003e. Under natural conditions, many benthic juveniles of \u003cem\u003eG. monodon\u003c/em\u003e can be found at concentrations below 0.7 mg O\u003csub\u003e2\u003c/sub\u003e L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, and down to 0.2 mg O\u003csub\u003e2\u003c/sub\u003e L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (~\u0026thinsp;30\u0026ndash;37\u0026deg;S) \u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e,\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e in waters of about 11\u0026deg;C\u003csup\u003e\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003ePostprandial metabolism in juveniles of \u003cem\u003eG. monodon\u003c/em\u003e significantly depended on the temperature-DO interaction, that is, in general agreement with expected results\u003csup\u003e\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e\u003c/sup\u003e. Even though postprandial oxygen consumption results from several processes (mechanical digestion, absorption, assimilation), most of it is related to the latter\u003csup\u003e\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e\u003c/sup\u003e, in particular protein synthesis, and it can be interpreted as the cost of growth\u003csup\u003e\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e\u003c/sup\u003e. Therefore, the comparative analysis of postprandial metabolism (total energy expenditure) responses to different environmental conditions for organisms, in the same developmental stage and fed with the same type of food, can be related to the rates of protein synthesis\u003csup\u003e\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e,\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e\u003c/sup\u003e that will be used in all other metabolic activities\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e. In postprandial curve the total SDA depends both on the increment of oxygen consumption above the RMR as well as on its duration\u003csup\u003e\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e\u003c/sup\u003e. Invertebrates are expected to have a 2- to 3-fold increase in oxygen consumption over the routine metabolism\u003csup\u003e\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e\u003c/sup\u003e, that is congruent with results in normoxia at 11\u0026deg;C (SDA scope 2.63). But not at 21\u0026ordm;C, when the highest SDA peak observed, but only represented a 1.2 fold increase over RMR.\u003c/p\u003e \u003cp\u003eIn postprandial curve, increases of SDA peak with temperature are expected\u003csup\u003e\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e\u003c/sup\u003e, while the total oxygen consumption during the postprandial process might be conserved due to reductions in SDA duration at higher temperatures (within certain temperature range). In the present case, SDA time did not vary significantly between temperatures, so overall SDA energy was larger at higher temperature, but the overall SDA versus RMR expenditure was reduced in comparison with lower temperatures. The differences the SDA energy (in normoxia) between temperatures could be related to the early stage of development analyzed (juveniles), in fish it has been observed that the ability to compensate SDA expenditure with the increment of temperature is reached gradually during ontogeny\u003csup\u003e\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eLow DO conditions might impose a restriction in the peak of postprandial SDA (if the maximum oxygen uptake capacity was structurally limited) and therefore on SDA scope, as oxygen decreases, becoming a constraint to energy acquisition specially at high temperature\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e. In this case, the SDA scope increased with the decrease in temperature, and this trend continues with the decrease in DO. The decrease in the SDA scope at 11\u0026deg;C in the two low DO concentrations indicates that despite maintaining RMR stable at these oxygen conditions, juveniles do not sustain post-prandial normoxic oxygen uptake rates but maintained the overall SDA energy throughout hypoxic conditions.\u003c/p\u003e \u003cp\u003eA key step for metabolic rules and evolution is the capacity of an organism to uptake and deliver of oxygen to tissues, cells and mitochondria\u003csup\u003e\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e\u003c/sup\u003e. The maximum delivery capacity of an organism via the routine rate could suggest limits to fitness in response to environmental conditions as usually evaluated for the scope for activity, growth but also SDA scope\u003csup\u003e\u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e58\u003c/span\u003e\u003c/sup\u003e. If that is the case, and the postprandial SDA peak would reflect such maximum uptake and delivery capacity to take advantage of external food sources, the length of time of postprandial activity, could compensate for the overall reduction of the upper limit of uptake, to meet a more stable level of energy SDA. Considering that the juvenile stage, when the organism is compelled to grow, the delivery hypothesis would not necessary be in agreement with the lack of compensation between high and low oxygen conditions for 11\u0026deg;C observed in this study. Because organisms do grow and are usually found in this conditions in the field at 30\u0026ndash;37\u0026deg;S (\u0026lt;\u0026thinsp;0.7 mg O2 L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and ~\u0026thinsp;11\u0026deg;C, the adjustment of ATP demanding processes to varying temperatures and oxygen concentrations would provide a better argument to explain observed experimental results.\u003c/p\u003e \u003cp\u003eHypoxia at 21 C allowed for an increase over the SMR during postprandial metabolism, even below the Pcrit, except for the lowest level tested (Figs.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e and \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). This is a common response in crustaceans within limited low-oxygen conditions below the Pcrit \u003csup\u003e\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e\u003c/sup\u003e. Within this environmental oxygen range, it should be the rate of internal (organ level) oxygen demand that sets the rate of whole organism oxygen uptake. Under severe hypoxia and higher temperature (0.7 mg DO and 21\u0026deg;C), \u003cem\u003eG. monodon\u003c/em\u003e did not show a postprandial peak suggesting that at this high temperature, which enhances the basic demand for DO and low availability of DO (0.7 mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) the oxygen uptake rate is already at a maximum possible uptake rate, at the whole individual capacity. At 21\u0026deg;C and 0.7 mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e it would not be possible to digest and assimilate ingested food, and consequently the organisms must avoid these conditions.\u003c/p\u003e \u003cp\u003eWe expect that a plastic species such as G. monodon will not necessary restric its latitudinal distribution range in climate change scenarios but their vertical distribution and life cycle parameters. In scenarios of Climatic Change, it has been projected that OMZs would intensify (increase vertical, latitudinal and longitudinal extent) \u003csup\u003e\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e,\u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e60\u003c/span\u003e,\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e. The trend shows that the SE Pacific is one of the areas that will be least affected by increasing deoxygenation\u003csup\u003e\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e\u003c/sup\u003e. Nevertheless, changes in oxygen patterns are expected to affect the vertical distribution of coastal aerobic species as a result of the shallower oxycline\u003csup\u003e\u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e60\u003c/span\u003e\u003c/sup\u003e. At the same time, the water column of the SE Pacific has tended to cool (-0.2\u0026deg;C) over the last decades, a trend that is partly explained by the intensification of the southern wind and large-scale changes in coastal circulation\u003csup\u003e\u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e61\u003c/span\u003e,\u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e62\u003c/span\u003e\u003c/sup\u003e, and possibly due to multidecadal oceanic-atmospheric oscillatory modes\u003csup\u003e\u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e63\u003c/span\u003e\u003c/sup\u003e. Global climate models suggest that temperature rise over the SE Pacific would be lower than in other ocean basins mainly due to wind-driven circulation. Nevertheless, the shallower position of the oxygen isopleth would connect the upper limit of the OMZ with higher temperatures, especially north of 24\u0026deg;S\u003csup\u003e\u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e60\u003c/span\u003e\u003c/sup\u003e. If this trend continues, two scenarios could be expected: (i) a reduction of the oxygenated area contracting the benthic habitat of \u003cem\u003eG. monodon\u003c/em\u003e and anchovy in Peru, or (ii) an extension of the pelagic habitat to \u003cem\u003eG. monodon\u003c/em\u003e to the south of 20\u0026deg;S.\u003c/p\u003e \u003cp\u003eLatitudinal changes in habitat use of this species would have an ecosystemic effect, as this species is key to the trophic networks of both (benthic and pelagic) environments, including vertebrate and invertebrate species, some of which are of commercial importance (horse mackerel and hake). Based on our results we predict that in a scenario of surface cooling and expansion of hypoxic conditions, in species with a similar life history plasticity as documented here for \u003cem\u003eG. monodon\u003c/em\u003e, the proportion of populations with pelagic life habits will increase. In contrast, for species without this plasticity, it can be expected that their populations will contract to areas that maintain favourable oxygen-temperature conditions.\u003c/p\u003e"},{"header":"METHODS","content":"\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eBio-physical metadata compilation and analysis\u003c/h2\u003e \u003cp\u003eThe latitudinal variability (meridional section) of mean temperature and dissolved oxygen concentrations over the continental shelf of western South America was characterized after extracting available temperature/oxygen profiles from the World Ocean Database (WOD, \u003cspan class=\"ExternalRef\"\u003ewww.nodc.noaa.gov\u003c/a\u003e\u003c/span\u003e\u003cspan address=\"http://www.nodc.noaa.gov\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e) from 5\u0026deg;S to 35\u0026ordm;S and from the coast to offshore distances corresponding to station depths of 200 m. After checking the quality of temperature and DO values, they were averaged over time every 1\u0026ordm; of latitude at standard depths. Afterwards the depths and temperature of limits of the OMZ were identified for each averaged profile, considering three values of oxygen isopleth 0.5, 1 and 2 ml O\u003csub\u003e2\u003c/sub\u003e L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Finally, continental shelf width in km (distance from the coast to the 200 m isobaths) was estimated from the database GEBCO 2014 Grid, and also averaged for each degree of latitude.\u003c/p\u003e \u003cp\u003eA database for \u003cem\u003eG. monodon\u003c/em\u003e presence/absence was constructed after reviewing surveys conducted over the continental shelf of western South America (5\u0026deg;S \u0026minus;\u0026thinsp;37\u0026ordm;S) between 1965 and 2015 (Supplementary Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e online); 56 published papers and unpublished reports were used. The matrix of presence/absence of \u003cem\u003eG. monodon\u003c/em\u003e in pelagic and benthic habitats for every degree of latitude was constructed using direct fisheries assessment reports of free-living individuals of this species as well as its presence in the diet of pelagic/demersal predators. Three types of life habits were distinguished by latitudinal degree: 1-benthic adults, 2-pelagic adults, and 3-both benthic and pelagic adults combined. A Random Forest analysis was utilized to relate the occurrence of the life habits of \u003cem\u003eG. monodon\u003c/em\u003e (benthic, pelagic, and both combined) to a function of shelf width, depth limits of the OMZ (0.5, 1 and 2 ml O\u003csub\u003e2\u003c/sub\u003e L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), and temperature at the same oxygen levels throughout its distribution in the SE Pacific. Analyses were carried out using the library Random Forest\u003csup\u003e\u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e64\u003c/span\u003e\u003c/sup\u003e in Rstudio software (R Core Team, 2024)\u003csup\u003e\u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e65\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eEcophysiological experiments\u003c/h3\u003e\n\u003cp\u003eJuveniles of \u003cem\u003eG. monodon\u003c/em\u003e were obtained from plankton, near Concepci\u0026oacute;n Bay, southern Chile (36\u0026deg;28.4\u0026acute;S, 73\u0026deg;00.8\u0026acute;W) on March 19, 2014. Specimens were captured during the night, between 0\u0026ndash;30 m, with a bongo net (300 \u0026micro;m), and immediately placed at 11\u0026deg;C-12\u0026deg;C to be transported to the Laboratory of Crustacean Ecophysiology (LECOFIC) at the Universidad Austral de Chile, Chile (Puerto Montt), where all the ecophysiological experiments were conducted. Before the experiments were set up, the collected juveniles were maintained in large aquaria with recirculating micro-filtered seawater, normoxia temperatures between 10\u0026deg;C-12\u0026deg;C, and they were fed every other day with \u003cem\u003eArtemia\u003c/em\u003e spp. nauplii.\u003c/p\u003e \u003cp\u003eThe critical point (Pcrit) of standard oxygen consumption rate was determined through closed respirometry at two different temperatures (11\u0026deg;C and 21\u0026deg;C). For each temperature, individuals were incubated at eight starting dissolved oxygen (DO) levels (0.7, 1.4, 2.9 3.5, 4.5, 5.5, 6.5 and ~\u0026thinsp;8 mg O\u003csub\u003e2,\u003c/sub\u003e within the 1.5 to 24.3 kPa). First, juveniles were individually transferred to 1 L Schott bottles, and kept without feeding for 24 h in normoxia previous to the experiment. Experimental bottles were prepared with water at the desired temperature-DO initial conditions, the previously separated juveniles were introduced individually in these bottles one hour before measurements started. Oxygen concentration was determined at the start and after 5 hours of incubation. Six replicates and six controls (without juveniles) for each treatment were run. The DO treatments were achieved by bubbling seawater with N\u003csub\u003e2\u003c/sub\u003e gas. The temperature was maintained with a thermoregulated bath, where bottles were completely submerged. Initial and final DO were measured with an optic sensor, connected to Microx TX3AOT oxygen meter (PreSens, GmbH, Germany) and used to calculate oxygen consumption. After each experiments individuals were immediately weighted, frozen and stored at \u0026minus;\u0026thinsp;80\u0026deg;C until biochemical analyses.\u003c/p\u003e \u003cp\u003ePostprandial metabolism (peak, time, scope and SDA, details in Supplementary Material) was determined at four DO levels (0.7, 1.4, 2.9 and ~\u0026thinsp;8 mg O\u003csub\u003e2\u003c/sub\u003e L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, equivalent to 0.5, 1, 2 ml L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and normoxia, respectively) for three temperatures (11\u0026deg;C, 15\u0026deg;C, and 21\u0026deg;C). Individually reared juveniles remained fasting for 24h. They were then fed for 30 min with freshly hatched \u003cem\u003eArtemia\u003c/em\u003e nauplii (~\u0026thinsp;1500 nauplii/100 ml). Non-consumed nauplii were removed after the 30 min feeding period. Juveniles were contained in Schott bottles (100 ml) connected to an open system, where the input is connected to peristaltic pumps (maintaining constant flow: ~0.19 L h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) and the output connected to a Sensor Dish Reader SDR (PreSens, GmbH, Germany) of 24 sensor spot (DO log every 15 sec). Postprandial metabolism was measured for 24 h. The DO treatments were achieved by bubbling seawater with nitrogen, while the temperature was maintained by completely covering the bottles within a thermoregulated bath. The measurements were run for two oxygen concentrations and one temperature per day. Thereafter each individual was weighed and immediately frozen and stored at \u0026minus;\u0026thinsp;80\u0026deg;C until biochemical analyses.\u003c/p\u003e \u003cp\u003eTo characterize the postprandial metabolism, oxygen consumption curves were constructed (mg O\u003csub\u003e2\u003c/sub\u003e per g WW\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) as a function of time, for each combined treatment of Temperature-DO. As described by Secor (2009)\u003csup\u003e\u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e66\u003c/span\u003e\u003c/sup\u003e, five descriptors of postprandial metabolism were extracted from each curve: (i) Standard metabolic rate (SMR), (ii) SDA Peak, (iii) SDA scope, (iv) total SDA (energy), and (v) SDA duration (time).\u003c/p\u003e \u003cp\u003eAbdominal muscle (20 mg) of deep-frozen replicates of juvenils \u003cem\u003eG. monodon\u003c/em\u003e from both experimental set-ups were separated for the determination of Lactate dehydrogenase apparent specific activity (LDH activity). The cephalotorax of juveniles (30 mg) frozen after postprandial experiments were used to determine Heat Shock Protein 70 (HSP70) and total protein concentrations, following Brokordt et al. (2015)\u003csup\u003e\u003cspan citationid=\"CR67\" class=\"CitationRef\"\u003e67\u003c/span\u003e\u003c/sup\u003e. All analyses were carried out using EPOCH microplate spectrophotometer (BioTeck).\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eEcophysiological data analysis\u003c/h2\u003e \u003cp\u003eAll the analyses described below were conducted in R software (R Core Team, 2024). In order to calculate Pcrit, experimental DO were expressed in kPa. The mean between the initial and final DO concentration in each bottle was used as the reference for each respiration value. A regression analysis of oxygen consumption (mg O\u003csub\u003e2\u003c/sub\u003e h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003eg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) as a function of oxygen concentration (kPa) was adjusted for each temperature. The regression was fitted with library ggplot2 (version 3.5.1\u003csup\u003e68\u003c/sup\u003e), function geom_smooth and method \u0026ldquo;loess\u0026rdquo; (Local polynomial regression fitting). This allowed us to determine the breakpoint (Pcrit), represented by a change of slope in the response variable as a function of the independent variable. The same procedure was followed to relate LDH apparent specific activity and DO.\u003c/p\u003e \u003cp\u003eThe postprandial results were represented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (library Rmisc, version 1.5\u003csup\u003e69\u003c/sup\u003e). postprandial parameters, LDH activity and HSP70 concentration were compared between treatments (DO/temperature) using factorial two-way ANOVA, followed by a Tukey \u003cem\u003epost-hoc\u003c/em\u003e test (HSD Tukey, library agricolae, version 1.2\u0026ndash;4\u003csup\u003e70\u003c/sup\u003e). Previously, normal distribution (Normal Q-Q plot) and homogeneity of variances (Levene\u0026rsquo;s test) were checked (library Car version 2.1\u0026ndash;4\u003csup\u003e71\u003c/sup\u003e). The figures were made with the library ggplot2 (version 3.5.1\u003csup\u003e68\u003c/sup\u003e).\u003c/p\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eM.A.G. and B.Y. developed the concept for this study. M.A.G., B.Y., M.R. and M.P., K.B. K.P. performed analysis. K. P. K.B., M.R., M.T., verified the analysis and provided data. M.A.G. and B.Y. wrote the original manuscript. M.A.G., M.R., M.P. and B.Y. designed the figures M.T. K.P. K.B commented on the results. All authors discussed and commented on the manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eThis study was funded by FONDECYT 1140831 (BY, MR, MT, KB, KP), FONDECYT 1140845 (MR), ANID \u0026ldquo;Becas Chile\u0026rdquo; Grant 21110922 (MAG), CLAP Project R20F0008 (MAG, MR, KB) and Anillo BiodUCCT ATE220044 (MAG, MP and MR). The authors thank the professionals Miguel Herrera, Juan Pablo Cumillaf, Andrea Mart\u0026iacute;nez, and Lucas Clavel (LECOFIC Team, Universidad de Valdivia), Katherine Jeno and William Far\u0026iacute;as (Team FIGEMA, UCN). Dr. Leonardo Castro (UdeC) for facilitating the juvenils. Finally, we thank Lisa Levin (SCRIPS) for a critical review of the manuscript.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\u003cp\u003eSupplementary information accompanies this paper\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eCompeting Interests: The authors declare that they have no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eDeutsch, C., Ferrel, A., Seibel, B., P\u0026ouml;rtner, H. O. \u0026amp; Huey, R. B. 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URL: (2011). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://socserv.socsci.mcmaster.ca/jfox/Books/Companion\u003c/span\u003e\u003cspan address=\"http://socserv.socsci.mcmaster.ca/jfox/Books/Companion\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Global Climate Change and phenotypic plasticity, Pleuroncodes monodon, “munida”, squat lobster, temperature-oxygen metabolic responses, Humboldt Current System OMZ","lastPublishedDoi":"10.21203/rs.3.rs-6198822/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6198822/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eWe examined how a species inhabiting a latitudinal gradient from surface oxygenated warm waters to subsurface severely oxygen-limited cold waters along the continental shelf of the Eastern South Pacific (ESP) is responding to the latitudinal temperature changes of low oxygen isopleths. We combined temperature-oxygen latitudinal sections from World Ocean Database, historical recordings of pelagic/benthic \u003cem\u003eGrimothea monodon\u003c/em\u003e occurrence through latitude and conducted laboratory experiments assessing juvenile\u0026rsquo;s routine and postprandial metabolism at realistic oxygen-temperature conditions. \u003cb\u003eS\u003c/b\u003equat lobsters main habits (pelagic to benthic) were related with temperature at the 2 ml O\u003csub\u003e2\u003c/sub\u003e L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (~\u0026thinsp;89 \u0026micro;M) oxygen isopleth. Warm (\u0026gt;\u0026thinsp;15\u0026deg;C) hypoxic upper oxygen minimum zone (OMZ) impairs \u003cem\u003eG. monodon\u003c/em\u003e all time permanence on benthic habitat or restrict it to pelagic habits. The physiological performance of juveniles (main migratory stage) was negatively affected by high temperature-hypoxia interaction. Routine metabolic rates showed a 60% decrease with hypoxia at high temperatures (21\u0026deg;C). Postprandial metabolism (as SDA) was mostly affected at high temperatures and low oxygen. \u003cem\u003eGrimothea monodon\u003c/em\u003e can adjust their life habits to a wide range of conditions along the ESP coast maintaining intergenerational capability to shift from one habit to the other, their expansion/restriction in vertical distribution, would allow for maintaining/expanding latitudinal ranges as benthic and pelagic food webs adjust to its availability as key prey item and humans to future fishing grounds.\u003c/p\u003e","manuscriptTitle":"Squat lobster latitudinal life habitat shifts and metabolic response to combined temperature and oxygen conditions in the Humboldt Current System","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-05-05 19:35:16","doi":"10.21203/rs.3.rs-6198822/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-05-26T07:48:37+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-05-23T14:34:04+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-05-22T21:21:52+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-05-22T15:12:35+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-05-18T22:12:57+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"178349567772062627764610603613892794627","date":"2025-05-13T14:00:03+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"204800680485209522082813650555121923591","date":"2025-05-12T00:30:55+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"261417469304681740696957407070980385815","date":"2025-05-09T09:05:43+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"267254137149396023662264951924208059813","date":"2025-05-09T08:03:30+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-04-28T21:13:35+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-04-28T08:21:58+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2025-03-28T13:52:24+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"0a469cd0-7f9a-4335-8196-eacbfdbb3276","owner":[],"postedDate":"May 5th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":47941518,"name":"Biological sciences/Biophysics"},{"id":47941519,"name":"Biological sciences/Ecology"},{"id":47941520,"name":"Biological sciences/Physiology"},{"id":47941521,"name":"Earth and environmental sciences/Ecology"},{"id":47941522,"name":"Earth and environmental sciences/Environmental sciences"},{"id":47941523,"name":"Earth and environmental sciences/Ocean sciences"}],"tags":[],"updatedAt":"2025-11-24T16:04:44+00:00","versionOfRecord":{"articleIdentity":"rs-6198822","link":"https://doi.org/10.1038/s41598-025-25984-4","journal":{"identity":"scientific-reports","isVorOnly":false,"title":"Scientific Reports"},"publishedOn":"2025-11-21 15:58:57","publishedOnDateReadable":"November 21st, 2025"},"versionCreatedAt":"2025-05-05 19:35:16","video":"","vorDoi":"10.1038/s41598-025-25984-4","vorDoiUrl":"https://doi.org/10.1038/s41598-025-25984-4","workflowStages":[]},"version":"v1","identity":"rs-6198822","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6198822","identity":"rs-6198822","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}