Indications of future performance of native and non-native adult oysters under acidification and warming

Climate change effects on aquaculture production and its sustainable management through climate-resilient adaptation strategies: a review

Aquaculture witnessed a remarkable growth as one of the fastest-expanding sector in the food production industry; however, it faces serious threat from the unavoidable impacts of climate change. Understanding this threat, the present review explores the consequences of climate change on aquaculture production and provides need based strategies for its sustainable management, with a particular emphasis on climate-resilient approaches. The study examines the multi-dimensional impacts of climate change on aquaculture which includes the shifts in water temperature, sea-level rise, ocean acidification, harmful algal blooms, extreme weather events, and alterations in ecological dynamics. The review subsequently investigates innovative scientific interventions and climate-resilient aquaculture strategies aimed at strengthening the adaptive capacity of aquaculture practices. Some widely established solutions include selective breeding, species diversification, incorporation of ecosystem-based management practices, and the implementation of sustainable and advanced aquaculture systems (aquaponics and recirculating aquaculture systems (RAS). These strategies work towards fortifying aquaculture systems against climate-induced disturbances, thereby mitigating risks and ensuring sustained production. This review provides a detailed insight to the ongoing discourse on climate-resilient aquaculture, emphasizing an immediate need for prudent measures to secure the future sustainability of fish food production sector.

Immediate and delayed effects of a heatwave and Prorocentrum lima ((Ehrenberg) Stein 1878) bloom on the toxin accumulation, physiology, and survival of the oyster Magallana gigas (Thunberg, 1793)

Warming could facilitate the intensification of toxic algal blooms, two important stressors for marine organisms that are predicted to co-occur more frequently in the future. We investigated the immediate and delayed effects of a heatwave and a simulated bloom (3 × 106 cells L-1) of the diarrhetic shellfish toxin (DST)-producing benthic dinoflagellate Prorocentrum lima on the survival, physiology (oxygen consumption rate, condition index, immune parameters), and toxin accumulation in the Pacific rock oyster Magallana (Crassostrea) gigas. Oysters exposed to both stressors contained higher mean DST concentrations (mean ± 1 SE: 173.3 ± 19.78 μg kg-1 soft tissue) than those exposed to P. lima bloom alone (120.4 ± 20.90 μg kg-1) and exceeded the maximum permitted levels for human consumption. Exposure to individual stressors and their combination modified the physiology of M. gigas. Oysters exposed to heatwave alone had significantly higher oxygen consumption rates (0.7 ± 0.06 mg O2 h-1 g-1) than the control (0.3 ± 0.06 mg O2 h-1 g-1). However, this was not observed in oysters exposed to both heatwave and P. lima (0.5 ± 0.06 mg O2 h-1 g-1). This alteration of the metabolic response to warming in the presence of P. lima may affect the ability of rock oysters to adapt to environmental stressors (i.e., a heatwave) to ensure survival. Immunomodulation, through changes in total hemocyte count, was observed in oysters exposed to P. lima alone and in combination with warming. Individual stressors and their combination did not influence the condition index, but one mortality was recorded in oysters exposed to both stressors. The findings of this study highlight the vulnerability of rock oysters to the predicted increased frequency of heatwaves and toxic algal blooms, and the increased likelihood of shellfish containing higher than regulatory levels of DST in warming coasts.

Differential effects of ocean acidification and warming on biological functioning of a predator and prey species may alter future trophic interactions

Independently, ocean warming (OW) and acidification (OA) from increased anthropogenic atmospheric carbon dioxide are argued to be two of the greatest threats to marine organisms. Increasingly, their interaction (ocean acidification and warming, OAW) is shown to have wide-ranging consequences to biological functioning, population and community structure, species interactions and ecosystem service provision. Here, using a multi-trophic experiment, we tested the effects of future OAW scenarios on two widespread intertidal species, the blue mussel Mytilus edulis and its predator Nucella lapillus. Results indicate negative consequences of OAW on the growth, feeding and metabolic rate of M. edulis and heightened predation risk. In contrast, Nucella growth and metabolism was unaffected and feeding increased under OAW but declined under OW suggesting OA may offset warming consequences. Should this differential response between the two species to OAW, and specifically greater physiological costs to the prey than its predator come to fruition in the nature, fundamental change in ecosystem structure and functioning could be expected as trophic interactions become disrupted.

Do global environmental drivers' ocean acidification and warming exacerbate the effects of oil pollution on the physiological energetics of Scylla serrata?

Global climate change-induced ocean warming and acidification have complex reverberations on the physiological functioning of marine ectotherms. The Sundarbans estuarine system has been under threat for the past few decades due to natural and anthropogenic disturbances. In recent years, petroleum products' transportation and their usage have increased manifold, which causes accidental oil spills. The mud crab (Scylla serrata) is one of the most commercially exploited species in the Sundarbans. The key objective of this study was to delineate whether rearing under global environmental drivers (ocean acidification and warming) exacerbates the effect of a local driver (oil pollution) on the physiological energetics of mud crab (Scylla serrata) from the Sundarbans estuarine system. Animals were reared separately for 30 days under (a) the current climatic scenario (pH 8.1, 28°C) and (b) the predicted climate change scenario (pH 7.7, 34°C). After rearing for 30 days, 50% of the animals from each treatment were exposed to 5 mg L^-1 of marine diesel oil for the next 24 h. Physiological energetics (ingestion rate, absorption rate, respiration rate, excretion rate, and scope for growth), thermal performance, thermal critical maxima (CT_max), acclimation response ratio (ARR), Arrhenius activation energy (AAE), temperature coefficient (Q₁₀), warming tolerance (WT), and thermal safety margin (TSM) were evaluated. Ingestion and absorption rates were significantly reduced, whereas respiration and ammonia excretion rates significantly increased in stressful treatments, resulting in a significantly lower scope for growth. A profound impact on thermal performance was also noticed, leading to a downward shift in CT_max value for stress-acclimated treatment. The present results clearly highlighted the detrimental combined effect of global climatic stressors and pollution on the physiological energetics of crabs that might potentially reduce their population and affect coastal aquaculture in forthcoming years.

The interactive effect of anti-sea lice pesticide azamethiphos and temperature on the physiological performance of the filter-feeding bivalve Ostrea chilensis: A non-target species

The pesticide azamethiphos used by the salmon industry to treat sea lice, is applied as a bath and subsequently discharged into the sea. The effects of azamethiphos concentration (0, 15 and 100 μg L^-1) on the physiology of the Chilean oyster (Ostrea chilensis) at two temperatures (12 and 15 °C) was examined. In all azamethiphos treatments, oysters kept at 15 °C had clearance rates (CR) higher than oysters kept at 12 °C. The oxygen consumption rate (OCR) increased at higher temperatures, except with 100 μg L^-1 of azamethiphos, where no changes were observed. Sixty days after the exposure, survival rates of 91 and 79% (15 and 100 μg L^-1, respectively), were observed compared to the controls, a situation independent of the experimental temperature. The interaction between temperature and pesticide has detrimental effects on the physiological performance and survival of O. chilensis, and these effects should also be assessed for other non-target species.

Effects of one-year exposure to ocean acidification on two species of abalone

Ocean acidification (OA) resulting from the absorption of excess atmospheric CO₂ by the ocean threatens the survival of marine calcareous organisms, including mollusks. This study investigated the effects of OA on adults of two abalone species (Haliotis diversicolor, a subtropical species, and Haliotis discus hannai, a temperate species). Abalone were exposed to three pCO₂ conditions for 1 year (ambient, ~ 880, and ~ 1600 μatm), and parameters, including mortality, physiology, immune system, biochemistry, and carry-over effects, were measured. Survival decreased significantly at ~ 800 μatm pCO₂ for H. diversicolor, while H. discus hannai survival was negatively affected only at a higher OA level (~ 1600 μatm pCO₂). H. diversicolor exhibited depressed metabolic and excretion rates and a higher O:N ratio under OA, indicating a shift to lipids as a metabolism substrate, while these physiological parameters in H. discus hannai were robust to OA. Both abalone failed to compensate for the pH decrease of their internal fluids because of the lowered hemolymph pH under OA. However, the reduced hemolymph pH did not affect total hemocyte counts or tested biomarkers. Additionally, H. discus hannai increased its hemolymph protein content under OA, which could indicate enhanced immunity. Larvae produced by adults exposed to the three pCO₂ levels were cultured in the same pCO₂ conditions and larval deformation and shell length were measured to observe carry-over effects. Enhanced OA tolerance was observed for H. discus hannai exposed under both of the OA treatments, while that was only observed following parental pCO₂ ~ 880 μatm exposure for H. diversicolor. Following pCO₂ ~ 1600 μatm parental exposure, H. diversicolor offspring exhibited higher deformation and lower shell growth in all pCO₂ treatments. In general, H. diversicolor were more susceptible to OA compared with H. discus hannai, suggesting that H. diversicolor could be unable to adapt to acidified oceans in the future.

Integrative assessment of biomarker responses in Mytilus galloprovincialis exposed to seawater acidification and copper ions

The interactive effects of ocean acidification (OA) and copper (Cu) ions on the mussel Mytilus galloprovincialis are not well understood. The underlying mechanisms also remain obscure. In this study, individuals of M. galloprovincialis were exposed for 28 days to 25 μg/L and 50 μg/L Cu ions at two pH levels (ambient level - pH 8.1; acidified level - pH 7.6). The mussels were then monitored for 56 days to determine their recovery ability. Physiological parameters (clearance rate and respiration rate), oxidative stress and neurotoxicity biomarkers (activities of superoxide dismutase, lipid peroxidation, catalase, and acetylcholinesterase), as well as the recovery ability of these parameters, were investigated in two typical tissues (i.e., gills and digestive glands). Results showed that (1) OA affected the bioconcentration of Cu in the gills and digestive glands of the mussels; (2) both OA and Cu can lead to physiological disturbance, oxidative stress, cellular damage, energy metabolism disturbance, and neurotoxicity on M. galloprovincialis; (3) gill is more sensitive to OA and Cu than digestive gland; (4) Most of the biochemical and physiological alternations caused by Cu and OA exposures in M. galloprovincialis can be repaired by the recovery experiments; (5) integrated biomarker response (IBR) analysis demonstrated that both OA and Cu ions exposure caused survival stresses to the mussels, with the highest effect shown in the co-exposure treatment. This study highlights the necessity to include OA along with pollutants in future studies to better elucidate the risks of ecological perturbations. The work also sheds light on the recovery of marine animals after short-term environmental stresses when the natural environment has recovered.

European Lobster Larval Development and Fitness Under a Temperature Gradient and Ocean Acidification

Climate change combined with anthropogenic stressors (e.g. overfishing, habitat destruction) may have particularly strong effects on threatened populations of coastal invertebrates. The collapse of the population of European lobster (Homarus gammarus) around Helgoland constitutes a good example and prompted a large-scale restocking program. The question arises if recruitment of remaining natural individuals and program-released specimens could be stunted by ongoing climate change. We examined the joint effect of ocean warming and acidification on survival, development, morphology, energy metabolism and enzymatic antioxidant activity of the larval stages of the European lobster. Larvae from four independent hatches were reared from stage I to III under a gradient of 10 seawater temperatures (13–24°C) combined with moderate (∼470 µatm) and elevated (∼1160 µatm) seawater pCO2 treatments. Those treatments correspond to the shared socio-economic pathways (SSP), SSP1-2.6 and SSP5-8.5 (i.e. the low and the very high greenhouse gas emissions respectively) projected for 2100 by the Intergovernmental Panel on Climate Change. Larvae under the elevated pCO2 treatment had not only lower survival rates, but also significantly smaller rostrum length. However, temperature was the main driver of energy demands with increased oxygen consumption rates and elemental C:N ratio towards warmer temperatures, with a reducing effect on development time. Using this large temperature gradient, we provide a more precise insight on the aerobic thermal window trade-offs of lobster larvae and whether exposure to the worst hypercapnia scenario may narrow it. This may have repercussions on the recruitment of the remaining natural and program-released specimens and thus, in the enhancement success of future lobster stocks.

Revisiting tolerance to ocean acidification: Insights from a new framework combining physiological and molecular tipping points of Pacific oyster

Studies on the impact of ocean acidification on marine organisms involve exposing organisms to future acidification scenarios, which has limited relevance for coastal calcifiers living in a mosaic of habitats. Identification of tipping points beyond which detrimental effects are observed is a widely generalizable proxy of acidification susceptibility at the population level. This approach is limited to a handful of studies that focus on only a few macro-physiological traits, thus overlooking the whole organism response. Here we develop a framework to analyze the broad macro-physiological and molecular responses over a wide pH range in juvenile oyster. We identify low tipping points for physiological traits at pH 7.3-6.9 that coincide with a major reshuffling in membrane lipids and transcriptome. In contrast, a drop in pH affects shell parameters above tipping points, likely impacting animal fitness. These findings were made possible by the development of an innovative methodology to synthesize and identify the main patterns of variations in large -omic data sets, fitting them to pH and identifying molecular tipping points. We propose the broad application of our framework to the assessment of effects of global change on other organisms.

Effects of ocean acidification and warming on the development and biochemical responses of juvenile shrimp Palaemon elegans (Rathke, 1837)

Anthropogenic CO₂ emissions have led to the warming and acidification of the oceans. Although, there is a growing of evidence showing that simultaneous occurrence of ocean acidification and ocean warming are threats to marine organisms, information on their combined effect on coastal shrimp species remains scarce. The purpose of this study was to estimate the combined effects of seawater acidification and warming on growth-related traits and biochemical responses of P. elegans juveniles. In this work, shrimp were exposed for 65 days at 4 experimental conditions: pH 8.10 * 18 °C, pH 7.80 * 18 °C, pH 8.10 * 22 °C, pH 7.80 * 22 °C. The results showed that low pH decreases the lipid content by ∼13% (p < 0.05). Higher temperature reduced the condition factor by ∼11%, the protein content by ∼20%, the PUFA by ∼8,6% and shortened moulting events by 5 days (p > 0.05) while the SFA increased ∼9.4%. The decrease in condition factor and protein was however more prominent in organisms exposed to the combination of pH and temperature with a decrease of ∼13% and ∼21%, respectively. Furthermore, essential fatty acids as EPA and DHA also decreased by ∼20% and ∼6.6% in low pH and higher temperature condition. Despite this study suggest that warming may have a greater impact than acidification, it has been shown that their combined effect can exacerbate these impacts with consequences for the shrimp's body size and biochemical profile.

Combined effects of ocean warming and acidification on marine fish and shellfish: A molecule to ecosystem perspective

It is expected that by 2050 human population will exceed nine billion leading to increased pressure on marine ecosystems. Therefore, it is conjectured various levels of ecosystem functioning starting from individual to population-level, species distribution, food webs and trophic interaction dynamics will be severely jeopardized in coming decades. Ocean warming and acidification are two prime threats to marine biota, yet studies about their cumulative effect on marine fish and shellfishes are still in its infancy. This review assesses existing information regarding the interactive effects of global environmental factors like warming and acidification in the perspective of marine capture fisheries and aquaculture industry. As climate change continues, distribution pattern of species is likely to be altered which will impact fisheries and fishing patterns. Our work is an attempt to compile the existing literatures in the biological perspective of the above-mentioned stressors and accentuate a clear outline of knowledge in this subject. We reviewed studies deciphering the biological consequences of warming and acidification on fish and shellfishes in the light of a molecule to ecosystem perspective. Here, for the first time impacts of these two global environmental drivers are discussed in a holistic manner taking into account growth, survival, behavioural response, prey predator dynamics, calcification, biomineralization, reproduction, physiology, thermal tolerance, molecular level responses as well as immune system and disease susceptibility. We suggest urgent focus on more robust, long term, comprehensive and ecologically realistic studies that will significantly contribute to the understanding of organism's response to climate change for sustainable capture fisheries and aquaculture.

Marine heat waves differentially affect functioning of native (Ostrea edulis) and invasive (Crassostrea [Magallana] gigas) oysters in tidal pools

The frequency and duration of short-term extreme climatic events, such as marine heat waves (MHWs), are increasing worldwide. The rapid onset of MHWs can lead to short-term stress responses in organisms that may have lethal or sub-lethal effects. In addition, increased temperature variability and extremes are predicted to favour and facilitate the spread of non-native species, altering rates of key ecosystem processes and functions. It is possible, however, that compensatory mechanisms, such as increased feeding rates, may enable the maintenance of metabolic functioning and prevent detrimental temperature effects. Using a mesocosm-based approach, we experimentally tested for the effects of MHWs in tidal pools on the mortality, individual length, width and biomass, and respiration rates for both a native oyster, Ostrea edulis, and invasive oyster, Magallana gigas, with or without food supply. No mortality was recorded for either O. edulis or M. gigas for the duration of the four week experiment. Increases in length were greater in O. edulis compared to M. gigas but were not affected by temperature or food supply. Increases in width, however, did not differ between species but were reduced overall in heat wave treatments regardless of food supply. O. edulis gained more biomass than M. gigas in ambient treatments regardless of food supply but, in heat wave treatments, only gained greater biomass than M. gigas at additional levels of food supply. Respiration rates did not reflect changes in temperature or food supply in either species but differed through time, with greater rates post-heat wave in all treatments. Thermal responses of O. edulis and M. gigas to MHWs thus appear to be context dependent and, if food supply is sufficient, O. edulis may be able to maintain its presence in the intertidal. The ability of M. gigas to remain unaffected by fluctuating environmental conditions, however, suggests future resilience of invasive populations to climatic extremes that may result in competitive exclusion and a further decline in native oyster populations. This information is critical for developing effective management plans to ensure the sustainability of natural oyster populations whilst maintaining key ecosystem functioning.

Marine heatwaves have minimal influence on the quality of adult Sydney rock oyster flesh

Marine heatwaves (MHWs) are impacting marine biodiversity, including fisheries and aquaculture. However, it is largely unknown which species will be able to endure MHWs and at what price. Here, we applied elevated temperature (2 °C above ambient) and two different heatwave scenarios to adults of the economically important Sydney rock oyster (SRO, Saccostrea glomerata), and evaluated the impact on nutritional properties, gene expression profiles and immune health indicators. We found that elevated temperature (23 °C) and a variable heatwave (VHW) during winter caused some significant differences in the micronutrient and trace elements levels in oyster flesh. There was an increase of lead under VHW and a decrease in chromium, barium and aluminium under elevated temperature. Conversely, gene expression profiles and other physiological parameters, including flesh protein, fatty acid profiles and hemocyte numbers, were not affected by MHWs. These results indicate that adult SRO are reasonably resilient, and should continue to provide high-quality seafood, under near-future ocean warming and moderate heatwave scenarios.

Climate Change Effects on Aquaculture Production: Sustainability Implications, Mitigation, and Adaptations

Aquaculture continues to significantly expand its production, making it the fastest-growing food production sector globally. However, the sustainability of the sector is at stake due to the predicted effects of climate change that are not only a future but also a present reality. In this paper, we review the potential effects of climate change on aquaculture production and its implications on the sector's sustainability. Various elements of a changing climate, such as rising temperatures, sea-level rise, diseases and harmful algal blooms, changes in rainfall patterns, the uncertainty of external inputs supplies, changes in sea surface salinity, and severe climatic events have been discussed. Furthermore, several adaptation options have been presented as well as some gaps in existing knowledge that require further investigations. Overall, climate change effects and implications on aquaculture production sustainability are expected to be both negative and positive although, the negative effects outweigh the positive ones. Adapting to the predicted changes in the short-term while taking mitigation measures in the long-term could be the only way toward sustaining the sector's production. However, successful adaptation will depend on the adaptive capacity of the producers in different regions of the world.

Long-term environmental tolerance of the non-indigenous Pacific oyster to expected contemporary climate change conditions

The current global redistribution of biota is often attributed to two main drivers: contemporary climate change (CCC) and non-indigenous species (NIS). Despite evidence of synergetic effects, however, studies assessing long-term effects of CCC conditions on NIS fitness remain rare. We examined the interactive effects of warming, ocean acidification and reduced salinity on the globally distributed marine NIS Magallana gigas (Pacific oyster) over a ten-month period. Growth, clearance and oxygen consumption rates were measured monthly to assess individual fitness. Lower salinity had a significant, permanent effect on M. gigas, reducing and increasing clearance and oxygen consumption rates, respectively. Neither predicted increases in seawater temperature nor reduced pH had a long-term physiological effect, indicating conditions predicted for 2100 will not affect adult physiology and survival. These results suggest that M. gigas will remain a globally successful NIS and predicted CCC will continue to facilitate their competitive dominance in the near future.

An Integrated and Multibiomarker approach to delineate oxidative stress status of Bellamya bengalensis under the interactions of elevated temperature and chlorpyrifos contamination

Synergistic effects of warming on bioconcentration and receptiveness of pollutants are still poorly unravelled in conjunction with cellular and molecular responses. The present study addressed the impact of an environmental relevant dose of chlorpyrifos (organophosphate pesticide), under control (25 °C) and elevated levels of temperature (30 °C, 35 °C) in Bellamya bengalensis, a freshwater gastropod for 60 days across various endpoints. Multiple levels of biomarkers were measured: growth conditions (organ to flesh weight ratio, condition index), oxidative stress status (SOD, CAT, GST, LPO) and DNA damage (Comet assay-3^rd, 30^th and 60^th days only) after acute (24, 48 and 72 h) and long-term exposures (10^th, 20^th, 30^th, 40^th, 50^th and 60^th days). An integrated biomarker response (IBR) strategy was adapted to amalgamate results generated from various biomarkers to assess organism's vulnerability to pesticide pollution and how it may shift with warming climate. Significant changes were observed in growth conditions under longer exposure periods. Acute as well as long-term exposures enhanced the antioxidant and detoxification enzyme activity. DNA damage was extensive under longer exposure to stress howbeit was also significantly escalated under acute severe warming. Antioxidant and detoxification mechanisms fell short in counteracting cellular level damage. The IBR results indicated long-term acclimation of B. bengalensis to elevated temperatures and pesticide contamination lead to an improved tolerance level howbeit, acute stress was more detrimental. This study provided evidence for the efficiency of employing an integrated biomarker approach for B. bengalensis in future bio-monitoring studies.

Metabolic recovery and compensatory shell growth of juvenile Pacific geoduck Panopea generosa following short-term exposure to acidified seawater

While acute stressors can be detrimental, environmental stress conditioning can improve performance. To test the hypothesis that physiological status is altered by stress conditioning, we subjected juvenile Pacific geoduck, Panopea generosa, to repeated exposures of elevated pCO₂ in a commercial hatchery setting followed by a period in ambient common garden. Respiration rate and shell length were measured for juvenile geoduck periodically throughout short-term repeated reciprocal exposure periods in ambient (~550 μatm) or elevated (~2400 μatm) pCO₂ treatments and in common, ambient conditions, 5 months after exposure. Short-term exposure periods comprised an initial 10-day exposure followed by 14 days in ambient before a secondary 6-day reciprocal exposure. The initial exposure to elevated pCO₂ significantly reduced respiration rate by 25% relative to ambient conditions, but no effect on shell growth was detected. Following 14 days in common garden, ambient conditions, reciprocal exposure to elevated or ambient pCO₂ did not alter juvenile respiration rates, indicating ability for metabolic recovery under subsequent conditions. Shell growth was negatively affected during the reciprocal treatment in both exposure histories; however, clams exposed to the initial elevated pCO₂ showed compensatory growth with 5.8% greater shell length (on average between the two secondary exposures) after 5 months in ambient conditions. Additionally, clams exposed to the secondary elevated pCO₂ showed 52.4% increase in respiration rate after 5 months in ambient conditions. Early exposure to low pH appears to trigger carryover effects suggesting bioenergetic re-allocation facilitates growth compensation. Life stage-specific exposures to stress can determine when it may be especially detrimental, or advantageous, to apply stress conditioning for commercial production of this long-lived burrowing clam.

Can an invasive species compensate for the loss of a declining native species? Functional similarity of native and introduced oysters

The widespread introduction of the Pacific oyster, Magallana gigas, has raised concerns regarding its potential impact on the functioning of invaded ecosystems. Concurrently, populations of the European oyster, Ostrea edulis, are in decline. We quantified the functional role of the native oyster, O. edulis, in terms of nutrient cycling and associated infaunal biodiversity and compared it directly to that of the invading oyster, M. gigas. The presence and density of both species were manipulated in the field and we tested for differences in concentration of ammonium, phosphate, total oxidised nitrogen and silicate in pore-water; total organic nitrogen and carbon in sediment; microbial activity; chlorophyll concentration; and the assemblage structure and richness of associated benthic taxa. No differences in nutrient cycling rates or associated benthic assemblages were identified between both oyster species. Nutrient concentrations were mostly affected by differences in oyster density and their significance varied among sampling events. Our findings suggest that M. gigas could compensate for the loss of ecosystem functions performed by O. edulis in areas where native oysters have been extirpated.

Changes in the biochemical and nutrient composition of seafood due to ocean acidification and warming

Ocean acidification and warming may threaten future seafood production, safety and quality by negatively impacting the fitness of marine species. Identifying changes in nutritional quality, as well as species most at risk, is crucial if societies are to secure food production. Here, changes in the biochemical composition and nutritional properties of the commercially valuable oysters, Magallana gigas and Ostrea edulis, were evaluated following a 12-week exposure to six ocean acidification and warming scenarios that were designed to reflect the temperature (+3 °C above ambient) and atmospheric pCO₂ conditions (increase of 350-600 ppm) predicted for the mid-to end-of-century. Results suggest that O. edulis, and especially M. gigas, are likely to become less nutritious (i.e. containing lower levels of protein, lipid, and carbohydrate), and have reduced caloric content under ocean acidification and warming. Important changes to essential mineral composition under ocean acidification and warming were evident in both species; enhanced accumulation of copper in M. gigas may be of concern regarding consumption safety. In light of these findings, the aquaculture industry may wish to consider a shift in focus toward species that are most robust to climate change and less prone to deterioration in quality, in order to secure future food provision and socio-economic benefits of aquaculture.