Climate change will continue to alter key physical and biological oceanographic processes throughout the global ocean, modifying environmental conditions for U.S. highly migratory fish species found in the Atlantic Ocean. The Atlantic Highly Migratory Species Climate Vulnerability Assessment evaluated the vulnerability of 58 species and stocks to projected ocean conditions, using a combined qualitative and quantitative analysis of species sensitivity (physiological, ecological, and behavioral attributes) and estimated exposure to possible future ocean stressors. Key modeled environmental variables included bottom and sea surface temperature, sea surface oxygen, and ocean acidification (pH), whereas the most influential biological attributes considered were population growth rate, stock size, and stock status. We produced vulnerability rankings (i.e., low, moderate, high, and very high) based on biological attribute sensitivity and exposure to the environmental variables, and separate analyses including estimated ability of distributional shifts, predicted directional effects of climate change, certainty, and data quality scores for the species and stocks assessed, with exceptions for species with undetermined geographic distributions. Of the 58 species and stocks assessed, 4 had very high vulnerability to climate change, 14 had high vulnerability, 22 had moderate vulnerability, 6 had low vulnerability, and 12 could not be assigned a rank. The majority (n = 45) of species and stocks had high ability for distributional shifts in response to projected changes in climate. Further, directional effect results suggest that climate change impacts on the majority of species and stocks will be neutral, implying that these species have life history or behavioral traits that impart some level of resilience and adaptability to the impacts of climate change. These results provide information for use in ecosystem-based fisheries management, particularly for prioritization of vulnerable species and stocks in conservation activities and research endeavors.
Continue reading ‘A climate vulnerability assessment for U.S. highly migratory fishes in the Atlantic Ocean’Posts Tagged 'fish'
A climate vulnerability assessment for U.S. highly migratory fishes in the Atlantic Ocean
Published 18 August 2025 Science ClosedTags: biological response, fish, North Atlantic, review
The influence of maternal size/age effects on the physiological responses of adult female gopher rockfish (Sebastes carnatus) to ocean acidification and hypoxia
Published 13 August 2025 Science ClosedTags: biological response, fish, laboratory, multiple factors, North Pacific, oxygen, physiology, reproduction
Climate change is rapidly reshaping the chemistry of the ocean. Fishes living in California coastal waters are experiencing increased ocean acidification and hypoxia (OAH) due to more frequent and intense upwelling. Nearshore rockfish may be particularly threatened by these conditions due to their long generational times. However, it is unknown how OAH may impact maternal physiology and reproduction in these viviparous fish. To understand the physiological effects of OAH during gestation, adult female gopher rockfish, Sebastes carnatus, were exposed to a variety of combined OAH stress treatments during different gestational stages. Routine metabolic rate (RMR), maximum metabolic rate (MMR), blood hematocrit (Hct), hemoglobin (tHb), pCO2, HCO3–, Na+, K+, Cl–, and metabolites, were measured to assess physiological responses to OAH stress. Ovarian oxygen was measured to examine the ability to buffer embryos against low oxygen. Fish exposed to higher OAH stress displayed elevated blood Hct, tHb, pCO2 and HCO3–, and decreased MMR, indicating attempted compensation for low pH and hypoxia (with varying levels of success), at increased physiological costs. Fish showed signs of buffering their ovaries against hypoxia. Lastly, pregnancy altered Hct and RMR under OAH exposure and size/age did not have a consistent effect on maternal physiology. By evaluating responses of maternal physiology to OAH stress, we can better understand how climate change affects fecundity, larval condition, and survival, influencing nearshore fisheries in an ever-changing climate.
Continue reading ‘The influence of maternal size/age effects on the physiological responses of adult female gopher rockfish (Sebastes carnatus) to ocean acidification and hypoxia’Assessing vulnerability of Arctic fish species to climate change
Published 12 August 2025 Science ClosedTags: Arctic, biological response, communitymodeling, fish, modeling, review
Climate change is impacting Arctic marine ecosystems at faster rates than the global average, challenging the management and conservation of biodiversity and living marine resources. This study examined the climate risks and vulnerabilities of 21 Arctic fish species occurring in the western Canadian Arctic using a fuzzy logic approach. Identified climatic hazards to marine species and their habitats are increasing temperature, decreasing sea ice cover, freshening, decreasing oxygen concentration, and acidification. The nature of these hazards included changes in mean conditions by 2050 (2041–2060), compared to the historical period (1979–2015 average) simulated from a regional coupled ice-ocean biogeochemical model and two coupled Earth system models under low and high emissions scenarios. A spatially-explicit algorithm was used to assess the risk and vulnerability in the Beaufort Sea shelf and slope and Amundsen Gulf (BS–AG) based on the species’ biological traits, biogeography and their exposure to climatic hazards. The results indicated high to very high exposure and risk of climate impacts across the ecosystem variables. Specifically, shallow areas were projected to be simultaneously exposed to more intense warming, reduced sea ice coverage, freshening, and acidification relative to the regional averages. In addition, for species occurring in the BS–AG, low adaptability and high sensitivity to climate hazards was identified. These applied tools and evaluations can inform marine spatial planning and climate adaptation efforts to help achieve conservation objectives and sustain ecosystem and community health in a changing Arctic climate.
Continue reading ‘Assessing vulnerability of Arctic fish species to climate change’Antarctic fishes in a changing climate: a comparative approach to predicting species-specific futures
Published 12 August 2025 Science ClosedTags: adaptation, Antarctic, biological response, fish, multiple factors, otherprocess, performance, temperature
The polar regions are experiencing climate change at the fastest rates on Earth and serve as bellwethers for the profound threats facing species, ecosystems, and physical processes worldwide due to uncurbed anthropogenic greenhouse gas emissions. My dissertation research focuses on early life stages of Antarctic fishes, which are thought to be particularly vulnerable to climate change due to their unique evolutionary history and specialization to their stenothermal habitat. I used a comparative framework, examining four closely related species in the Nototheniidae family – Trematomus bernacchii, Trematomus pennellii, Trematomus nicolai, and Pagothenia borchgrevinki – to understand how subtle interspecific variation in traits may impact species-specific performance under projected future ocean conditions. I first measured basal characteristics across the four species, as very little is known about Antarctic fishes at young life stages, focusing on metabolic traits and the exploration-avoidance axis of behavior, two key dimensions of species fitness and drivers of niche differentiation. While basal metabolic demands appeared relatively conserved across species at the juvenile life stage, I found divergent behavioral strategies that could be a critical driver of niche differentiation in Antarctic fish assemblages. T. bernacchii and T. pennellii showed risk-prone behavior, T. nicolai showed avoidant behavior, and P. borchgrevinki showed cautious exploratory behavior. I also observed a potentially conserved freezing strategy in response to novelty, which, when paired with in situ observations, indicates that freezing may be an important predator avoidance strategy in these fishes. I then focused on the two ‘risky’ species – Trematomus bernacchii and Trematomus pennellii – to explore how acclimation to projected future ocean warming and ocean acidification conditions may impact their risk-prone behavior. While acclimation to warming and elevated pCO₂ affected behavior in both species, the effect sizes of pCO₂ were small, and warming was the driving force behind behavioral modifications. In both species, fishes acclimated to ocean warming conditions demonstrated reduced exploratory activity and showed indications of neophilia. These responses amplified over time, and T. pennellii demonstrated a stronger response (i.e., effect sizes) in both behaviors. Consistent with previous physiological and behavioral studies, while limited, our results support the inference that T. pennellii have a particularly risk-prone strategy when faced with novelty that is amplified when acclimated to warming. My final chapter proposes a novel ‘ice reef’ framework and emphasizes how three-dimensional ice habitat formed by platelet, anchor, and brinicle ice may function as critical nursery and refugia habitats for young polar fishes. Drawing on in situ observations and the literature, I discuss the recurring behavioral, physiological, and morphological features across a diversity of polar fishes, suggesting ice-associated and ice-obligate life history strategies may be much more widespread than previously acknowledged. As climate change rapidly alters ice phenology and stability, the loss of ice reefs could jeopardize fish recruitment, community resilience, and key ecosystem services. This perspective underscores the urgent need to study ice reefs before they disappear altogether.
Continue reading ‘Antarctic fishes in a changing climate: a comparative approach to predicting species-specific futures’Epigenetic insights into physiological resilience: multigenerational readouts of CO2-induced seawater acidification effects on fish embryos
Published 5 August 2025 Science ClosedTags: adaptation, biological response, fish, laboratory, molecular biology, morphology, otherprocess, physiology, reproduction
Highlights
- Ocean acidification causes generation-specific developmental and metabolic changes.
- F2 embryos show enhanced resilience through transcriptional recovery mechanisms.
- Hypomethylation of ion transport genes drives adaptive acid-base regulation.
- Epigenetic inheritance facilitates multigenerational acclimation to acidification.
Summary
Anthropogenic CO2 emissions are acidifying oceans, threatening marine organisms during early development. We investigated multigenerational effects of projected 2100 acidification (pH 7.6) on marine medaka (Oryzias melastigma) embryos across three generations using integrated phenotypic, physiological, transcriptomic, and epigenetic analyses. Prolonged acidification altered developmental trajectories, with F2 embryos showing size reductions. Metabolic responses were generation-specific: F0 embryos displayed decreased ammonium excretion, while F1 and F2 maintained stable profiles. Transcriptomic analysis revealed generational changes in neurotransmission, ion regulation, and epigenetic pathways. F2 embryos exhibited attenuated transcriptional perturbations and partial restoration of acid-base homeostasis, suggesting enhanced adaptability. Adaptive gene expression correlated with hypomethylation recovery of ion transport genes AE1a and NHE2 in F2 embryos. Increased hypomethylated AE1a promoter CpG sites in F1 and F2 generations aligned with elevated transcription, indicating epigenetically-driven enhancement. These results demonstrate epigenetic control’s crucial role in multigenerational plasticity and adaptive responses to ocean acidification.
Continue reading ‘Epigenetic insights into physiological resilience: multigenerational readouts of CO2-induced seawater acidification effects on fish embryos’Adaptive responses of large yellow croaker Larimichthys crocea to ocean acidification: integrative analysis of gill and kidney transcriptomics and antioxidant enzyme activities
Published 21 July 2025 Science ClosedTags: adaptation, biological response, fish, laboratory, molecular biology, morphology, North Pacific, otherprocess, physiology
Anthropogenic acidification is a long-term challenge to marine ecosystems. Though coastal acidification is intensifying, the large yellow croaker (Larimichthys crocea) exhibits good adaptability to pH fluctuations, the underlying mechanisms of which remain poorly understood. This study investigated the morphology, antioxidant enzyme activity, and gene expression of L. crocea under varying acidification conditions (pH 8.1 (H group), 7.8 (M group), and 7.4 (L group)). Water pH fluctuations were also monitored to explore the physiological responses and potential adaptive molecular mechanisms of L. crocea under various acidified environments. The results indicated that the water pH decreased in the H group, significantly increased in the L group (p < 0.05), and remained stable in the M group during the experiment. The lowest MDA content and the highest antioxidant enzyme activities (CAT, SOD, GSH-Px) were observed in L. crocea at pH 7.8, suggesting pH 7.8 was optimal for L. crocea. Transcriptomic analysis revealed distinct gene expression patterns between the gills and kidneys under acidification stress. Differentially expressed genes (DEGs) in the gills were primarily observed between the M and L groups (62.3%), whereas in the kidneys, the majority of DEGs were observed between the M and H groups (43.2%). These findings suggested that the gills play a critical role in adapting to low pH in L. crocea, while the kidneys were more responsive to high pH. Enrichment analysis identified critical pathways, including vasopressin-regulated water reabsorption, mineral reabsorption, and aldosterone-regulated sodium reabsorption, which are associated with water and ion metabolism. These pathways play a pivotal role in the acid–base homeostasis and metabolism of L. crocea. These results provide insights into the adaptive mechanisms of L. crocea to acidified environments, with implications for aquaculture management and future ocean acidification adaptation.
Continue reading ‘Adaptive responses of large yellow croaker Larimichthys crocea to ocean acidification: integrative analysis of gill and kidney transcriptomics and antioxidant enzyme activities’High sensitivity to ocean acidification in wild out-migrating juvenile Pacific salmon is not impacted by feeding success
Published 18 July 2025 Science ClosedTags: biological response, fish, laboratory, molecular biology, mortality, multiple factors, North Pacific, physiology, reproduction
Salmon populations are declining worldwide, with high mortality rates during juvenile marine migration presenting a bottleneck to recruitment. The ocean conditions along the main migratory route of juvenile salmon in British Columbia are characterized by high variability in CO2, with the amplitude, duration, and frequency of ocean acidification events exacerbated by climate change. Similarly, the variability in ocean conditions affects the abundance and diversity of plankton prey, leading to areas of food paucity for juvenile salmon. We investigated the combined effects of ocean acidification (control and 3200 μatm CO2) and food limitation (ad libitum, ½ ration, and food deprived) on the survival, condition, and gene expression profiles of juvenile Chum salmon (Oncorhynchus keta) to develop predictive biomarkers for CO2 exposure and food deprivation. Ocean acidification caused a direct 3-fold increase in mortality over 25 days of exposure, which was unaffected by food availability but differentially affected smaller fish. CO2 exposure induced transcriptomic changes in a suite of genes associated with ion regulation, while food deprivation was associated with a differential expression of stress, immune, and mortality markers, as well as reduced condition factor. Our data indicate that CO2 directly impairs ionoregulatory capacity to the point of failure in juvenile Chum salmon and that these effects cannot be compensated through increased energy from food. Applying our gene panels as biomarkers to a subset of fish with known exposure, we were able to accurately predict exposure to CO2 and food deprivation (74% and 90%, respectively). By combining these gene panels with previously established biomarkers for other environmental stressors, the recent environmental stress history of wild fish can be determined and can be used in models to predict salmon returns, informing fisheries management and conservation efforts.
Continue reading ‘High sensitivity to ocean acidification in wild out-migrating juvenile Pacific salmon is not impacted by feeding success’Cross-generational plasticity in Atlantic silversides (Menidia menidia) under the combined effects of hypoxia and acidification
Published 17 July 2025 Science ClosedTags: biological response, fish, laboratory, molecular biology, mortality, multiple factors, North Atlantic, oxygen, physiology, reproduction
We investigated the potential for cross-generational plasticity to influence how offspring respond to hypoxia and ocean acidification (hereafter HypOA) in the coastal forage fish Atlantic silverside (Menidia menidia). Mature wild silversides were treated with a control (dissolved oxygen (DO):100% air saturation (a.s.) / pCO2: 650 µatm) or HypOA conditions (DO: 40% a.s. / pCO2: 2300 µatm) for 10 days prior to spawning. Their offspring were reared under both treatments in factorial experimental design. Parental environment had minimal effects on offspring phenotype: exposure to HypOA reduced survival and developmental rates regardless of parental treatment. However, RNAseq analysis revealed that direct offspring exposure to HypOA induced substantial transcriptional changes, with 1,606 differentially expressed transcripts (DETs) in larvae from control parents. These changes affected neural development, synaptic signaling, oxygen acquisition, and extracellular matrix organization. In contrast, larvae from HypOA-exposed parents exhibited a muted transcriptional response to HypOA, with only 4 DETs. Although we did not detect a statistically significant interaction between parental and offspring environments at the gene-wise level, a gene set test supported a consistent attenuation of expression changes in offspring from HypOA-treated parents. This pattern may be consistent with transcriptional frontloading, when stress-induced changes are retained and may modify future responses. However, because this effect did not improve offspring performance under HypOA, they are unlikely to represent an adaptive response. Instead, they may reflect non-adaptive carryover effects of parental exposure. Our findings highlight the potential for cross-generational effects to shape transcriptional plasticity, even in the absence of benefits to offspring.
Continue reading ‘Cross-generational plasticity in Atlantic silversides (Menidia menidia) under the combined effects of hypoxia and acidification’Physiological and growth responses of Black Sea salmon (Salmo labrax) to long-term salinity and high carbon dioxide stress
Published 16 July 2025 Science ClosedTags: biological response, Black Sea, fish, fisheries, growth, laboratory, molecular biology, morphology, multiple factors, physiology, salinity
Black Sea salmon (Salmo labrax), an anadromous salmonid species of regional importance, is increasingly considered for aquaculture in the Black Sea. This study investigates the physiological and growth responses of Black Sea salmon to seawater transfer, with a particular focus on carbon dioxide (CO₂) stress. The experiment began on 5 July 2022 with 720 fish (76.68±15.34 g) reared under semi-controlled conditions using a freshwater recirculating aquaculture system (RAS). On 12 October 2022, a group of fish was transferred to Black Sea water (18 ppt), and a subgroup was exposed to elevated CO₂ (1000 µatm pCO₂) until the end of the trial on 7 March 2023. Exposure to carbon dioxide showed negligible or minimal effects on seawater adaptation and growth. In contrast, physiological markers such as gill Na⁺/K⁺-ATPase (NKA) activity and the expression of nkaα1a, nkaα1b, and nkcc1a genes, along with growth metrics—including specific growth rate (SGR), condition factor (K value), and liver gene expression of igf-I, igfbp1b, ghr1, and ctsl—indicated that the fish were not physiologically prepared for seawater transfer in autumn. These findings suggest that the commonly practiced autumn sea transfer in the region may lead to suppressed growth and suboptimal performance. The results emphasize the importance of aligning seawater transfer with the smoltification window to support fish health and optimize aquaculture outcomes in Black Sea salmon farming.
Continue reading ‘Physiological and growth responses of Black Sea salmon (Salmo labrax) to long-term salinity and high carbon dioxide stress’Impact of ocean acidification on skeletal structures in gilthead sea bream (Sparus aurata): in vitro and in vivo studies
Published 15 July 2025 Science ClosedTags: biological response, fish, growth, laboratory, Mediterranean, molecular biology, morphology, physiology
Highlights
- Ocean acidification affects bone mineralization.
- Ocean acidification modifies otolith size.
- Low extracellular pH increases the viability and mineralization of osteoblasts.
- Changes in cell culture pH modify the gene expression of osteoblasts.
Abstract
Ocean acidification is considered a significant risk to aquaculture, as it may adversely affect the growth and development of aquatic organisms. The effect of ocean acidification has been shown to impair the growth and survival of fish and to increase otoliths calcification in certain species; however, its effects on bone mineralization remain not well studied. The objective of the present study was to examine the effects of seawater acidification on the skeletal mineralization of gilthead sea bream juveniles, and to assess the direct impact of distinct pH levels on bone-derived cells development. After 68 days of exposure to low pH, fish exhibited a significantly reduced specific growth rate and elevated plasma pH levels, which influenced electrolyte concentrations such as potassium. Moreover, fish exposed to low pH showed increased otoliths size but no differences in shape. In bone, a higher vertebral length/height ratio was also observed, accompanied by significantly reduced opacity and increased expression of the osteoblast and osteoclast markers, alkaline phosphatase (alp) and matrix metalloproteinase 9 (mmp9), respectively, suggesting an elevated rate of bone turnover although reduced mineralization. In vitro, osteoblasts exposed to a low extracellular pH for 30 days exhibited increased viability and mineralization compared to cells maintained at a plasma pH or an alkaline pH. Additionally, the pH level significantly influenced the expression of several extracellular matrix components and osteoblast markers supporting those observations. Overall, these findings underscore the threat that ocean acidification poses to aquaculture, particularly through its impact on skeletal mineralization in gilthead sea bream, and highlight the importance of identifying approaches to farming resilient fish.
Continue reading ‘Impact of ocean acidification on skeletal structures in gilthead sea bream (Sparus aurata): in vitro and in vivo studies’Ocean acidification induces changes in circadian alternative splicing profiles in a coral reef fish
Published 14 July 2025 Science ClosedTags: biological response, fish, laboratory, molecular biology, South Pacific
Alternative splicing is a fundamental mechanism of gene expression regulation that increases mRNA diversity and can be partially regulated by the circadian clock. Time-dependent production of transcript isoforms from the same gene facilitates coordination of biological processes with the time of day and is a crucial mechanism enabling organisms to cope with environmental changes. In this study, we determined the impact of future ocean acidification conditions on circadian splicing patterns in the brain of fish, while accounting for diel CO2 fluctuations that naturally occur on coral reefs. The temporal splicing pattern observed across a 24-hour period in fish from the control group was largely absent in those exposed to either stable or fluctuating elevated CO2 conditions. Splicing patterns were influenced not only by an overall increase in CO2 concentration but also by its stability, with 6am and 6pm emerging as key timepoints when the majority of aberrant splicing events were identified. We found that fish in fluctuating CO2 conditions exhibited increased temporal plasticity in splicing events compared to fish in stable CO2 conditions. This was especially notable for genes associated with neural functioning. Our findings suggest that natural temporal splicing patterns in fish brains are disrupted by elevated CO2 exposure, with CO2 stability also influencing molecular responses. The increased plasticity in temporal splicing activity observed in fish in fluctuating CO2 environments may provide greater flexibility in biological responses to external pH changes, potentially enabling them to better cope with future ocean acidification conditions.
Continue reading ‘Ocean acidification induces changes in circadian alternative splicing profiles in a coral reef fish’Impact of ocean acidification on fish health and marine ecosystem dynamics
Published 11 July 2025 Science ClosedTags: algae, biological response, corals, fish, mollusks, phanerogams, phytoplankton, review, zooplankton
Ocean acidification (OA) causes an increase in carbon dioxide (CO2) and a reduction in the pH of ocean waters. This chapter reviews the current literature to investigate the adverse effects of OA on fish health and marine ecosystem dynamics. OA poses serious threats to marine biodiversity and ecosystem dynamics. Fish experience severe physiological problems such as impaired growth, development, tissue damage, Impaired behavioral changes, sensory and brain functions, and disruption in predator-prey interactions due to acidification with a 74% decline in survival rates of egg and larval stages. Besides affecting fish, OA also affects marine ecosystem dynamics: reducing calcification rates in calcifying species, increasing seagrass production, causing effects on habitat-forming species, and disrupting the food web. Vulnerable species, such as coral reef fish, show high sensitivity, risking the stability of their habitats. The United Nations recognized the OA as a threat to marine biodiversity through the Convention on Biodiversity. The future research needs to focus on understanding fish and marine animals’ adaptive mechanisms to OA, its interaction with other stressors, and global collaboration to address the underlying causes of OA.
Continue reading ‘Impact of ocean acidification on fish health and marine ecosystem dynamics’Larval Arctic cod (Boreogadus saida) exhibit stronger developmental and physiological responses to temperature than to elevated pCO2
Published 10 July 2025 Science ClosedTags: Arctic, biological response, fish, growth, laboratory, morphology, mortality, multiple factors, physiology, reproduction, temperature
High-latitude ecosystems are simultaneously warming and acidifying under ongoing climate change. Arctic cod (Boreogadus saida) are a key species in the Arctic Ocean and have demonstrated sensitivity to ocean warming and acidification as adults and embryos, but their larval sensitivity to the combined stressors is unknown. In a laboratory multistressor experiment, larval Arctic cod were exposed to a combination of three temperatures (1.8, 5 and 7.3°C) and two carbon dioxide (pCO2) levels (ambient: 330 μatm, high: 1470 μatm) from hatching to 6-weeks of growth. Mortality rates were highest at 7.3°C (5% day°1); however, both growth and morphometric-based condition were also highest at this temperature. When these metrics were assessed via a mortality: growth (M:G) ratio, 5°C appeared to be an optimal temperature for net population biomass, as faster growth at 7.3°C did not fully compensate for higher mortality. In contrast, although morphometric-based condition was lowest at 1.8°C, lipid-based condition was highest, which may reflect prioritization of lipid storage at cold temperatures. The capacity of larval Arctic cod to acclimate to a range of temperatures was exhibited by two lipid-based indicators of membrane fluidity, including a ratio of unsaturated to saturated fatty acids and a ratio of polar lipids to sterols. The effects of elevated pCO2 were subtle, as well as temperature- and metric dependent. When exposed to elevated pCO2 levels, Arctic cod at 1.8°C exhibited signs of lipid dysregulation, suggesting potential interference with membrane acclimation; larvae at 5°C were in lower morphometric-based condition; and larvae at 7.3°C had higher activity eicosanoid substrates, indicating possible physiological stress. Overall, Arctic cod physiological response to temperature variation was more pronounced than their response to elevated pCO2. Future projections of pCO2 effects on Arctic cod health in a warming ecosystem will need to consider the complexity of temperature-dependence and the specificity of multiple physiological responses.
Continue reading ‘Larval Arctic cod (Boreogadus saida) exhibit stronger developmental and physiological responses to temperature than to elevated pCO2’Climate vulnerability assessment of fish and invertebrates in the U.S. South Atlantic large marine ecosystem
Published 9 July 2025 Science ClosedTags: biological response, crustaceans, fish, mollusks, North Atlantic, review
Trait-based climate vulnerability assessment (CVA) is a rapid and repeatable approach to simultaneously assess the vulnerability of a large number of species to projected regional changes in climate. We conducted the first CVA in the U.S. South Atlantic Large Marine Ecosystem for 71 ecologically, economically, and culturally important fish and invertebrate species. The CVA was conducted by a 16-member panel based on scoring 12 biological sensitivity attributes and seven climate exposure factors. About two-thirds of the species were considered highly vulnerability to future climate projected under the RCP 8.5 emissions scenario, with diadromous species, invertebrates, and deepwater reef fishes the most vulnerable functional groups. Ocean acidification, sea surface temperature, and salinity were the exposure factors with the greatest influence on climate vulnerability, while population growth rate, population status, and early life history traits were the most important biological sensitivity attributes. More than two-thirds of the species had high potential for shifts in geographic distribution, due mostly to the prevalence of broadcast spawning, extensive larval dispersal, and high adult mobility of many species, and the generalist habitat requirements of several estuary-dependent and hard-bottom reef species. Some shifts in distribution have already occurred though potential relationships to environmental conditions associated with climate are not well-understood. Uncertainty analyses confirmed the robustness of the climate vulnerability rankings, but comparison of alternative types of elicited informed judgement did not always agree, suggesting higher uncertainty in climate vulnerability for some species. In addition, several species may benefit under future climate conditions, and climate effects on some species considered to be highly vulnerable may be of relatively small magnitude. These results can be used to prioritize conservation, research, and management efforts, and identify key uncertainties related to the impacts of future climate on fishery resources in the U.S. South Atlantic region.
Continue reading ‘Climate vulnerability assessment of fish and invertebrates in the U.S. South Atlantic large marine ecosystem’Impacts of ocean acidification and altered prey fatty acids on the early development of northern rock sole (Lepidopsetta polyxystra) larvae
Published 3 July 2025 Science ClosedTags: biological response, fish, laboratory, morphology, mortality, multiple factors, North Pacific, physiology, reproduction
Highlights
- Carbon dioxide (CO2) and dietary fatty acids (FAs) had stage-specific effects on northern rock sole larvae.
- After 2-weeks of feeding, larvae had faster growth under elevated CO2 conditions.
- After 5-weeks of feeding, larvae had higher lipid storage when fed a diet with balanced-essential FAs.
Abstract
Ocean acidification (OA) is predicted to affect the physiological rates of larval fish and invertebrates and is also expected to significantly impact marine fisheries through alteration of food webs. We examined whether mortality rates, body size, and condition of first-feeding larval northern rock sole, Lepidopsetta polyxystra, were synergistically influenced by prey quality (essential fatty acids, EFAs) and high carbon dioxide (CO2) exposure. Larvae were exposed to ambient and high CO2 levels (∼ 330 vs. 1020 μatm) and were fed diets with balanced or unbalanced EFA ratios for 7 weeks immediately following hatch. After 2 weeks, significant effects from CO2 and diet were observed, with the largest larvae occurring in the high CO2 exposure group that received a balanced EFA diet. After 5 weeks of exposure, the effects of elevated CO2 had a diminished impact on larval size, but larvae reared on the balanced EFA diet maintained higher lipid-based condition metrics than those fed an unbalanced EFA diet. Survival was variable across replicate tanks and not significantly different between treatments. This study suggests that L. polyxystra larvae are most vulnerable to OA and food web change at different points in their development. Further understanding of these ecosystem effects will be required to predict the impacts of OA on northern rock sole fisheries.
Continue reading ‘Impacts of ocean acidification and altered prey fatty acids on the early development of northern rock sole (Lepidopsetta polyxystra) larvae’Ocean acidification and elevated temperatures alter the behavior of a sub-Antarctic fish
Published 3 June 2025 Science ClosedTags: Antarctic, biological response, fish, laboratory, multiple factors, performance, temperature
Highlights
- Climate change stressors impair the behavoir of subantarctic fish.
- Activity levels of E. mclovinus increased with higher temperatures.
- Future pCO2 levels increased fish’s boldness.
- Implications of behavioral changes on the species’ fitness remain unknown.
Abstract
The interaction of multiple climate change stressors can affect the behavior of marine fish. While these effects have been reported in tropical and temperate species, much less is known for fish inhabiting high latitudes. We analyzed the combined effects of ocean acidification and the highest and lowest seasonal temperatures on the activity level and boldness of Eleginops maclovinus, an ecologically and commercially important notothenioid fish from the subantarctic area. Juveniles were acclimated for one month to two temperatures (T = 4 and 10 °C) and two pCO2 levels (∼500 and ∼1800 μatm) in a full factorial design. In an open field test, the time spent active was significantly affected by temperature, with fish at 10 °C 1.63 times more active than those at 4 °C, but not by pCO2 or the interaction (T × pCO2). No differences were observed in the average swimming velocity measured when active, nor in the time spent in the inner zone of the tank. A refuge emergence test indicated increased boldness under near-future pCO2 levels with fish emerging 2.06 (4 °C) and 1.23 (10 °C) times faster than those acclimated to present-day pCO2 levels. The disruptions of these fundamental behaviors by these climate-driven stressors could have consequences for foraging and predator-prey interactions, with likely detrimental effects on the interactions among sympatric subantarctic fishes under projected climate change scenarios.
Continue reading ‘Ocean acidification and elevated temperatures alter the behavior of a sub-Antarctic fish’Examining behavioral alterations in zebrafish (Danio rerio) larvae in the context of anthropogenic climate change
Published 9 May 2025 Science ClosedTags: biological response, fish, laboratory, multiple factors, performance, reproduction, temperature
Behavioral responses induced by climate change in fish have received increased attention in recent years. Near future projected CO₂ levels (420 µatm to 1000 µatm) and increased temperature (~4 °C) expected in ocean and freshwater basins by 2100 have been shown to impair various behaviors such as locomotor activity and learning in early life stage fish. Despite widespread characterization, we know little about why these disruptions occur and how compounded effects of climate change might disrupt behavioral paradigms. Using the biomedical research model, the zebrafish (Danio rerio), a species with a well-documented behavioral repertoire and broadly utilized for mapping neural activity linked to behavior, this study aimed to assess how elevated CO₂ and temperature may affect behavior during early development. Larvae 6-7 days post fertilization were acclimated to either control (420 µatm CO₂; 28 °C) or 1,000 µatm pCO₂ and temperatures of 32 °C combined or singly before being subjected to various behavioral assays, consisting of acoustic- and visual stimuli to examine startle responses and their habituation. The results suggest that temperature more than CO₂ significantly altered the startle response, and to some extent, the habituation of this response. Both acoustic- and visual startle response were negatively affected by climate change relevant heat-exposure, while aquatic acidification had no significant effect on the acoustic startle response singly. Conversely, habituation appears to have increased under elevated temperature treatment in isolation compared to ambient levels. This experiment may help highlight zebrafish’s potential as a model organism for further climate- behavioral and physiological investigations, supported by their advanced gene editing and transgenic tools, optical transparency, and compatibility with high-throughput screening approaches.
Continue reading ‘Examining behavioral alterations in zebrafish (Danio rerio) larvae in the context of anthropogenic climate change’Evaluating the impact of ocean acidification on seafood – a global approach
Published 23 April 2025 Science ClosedTags: biological response, crustaceans, echinoderms, fish, fisheries, growth, mitigation, mollusks, mortality, review
The quality of human life and food security are closely linked to the health of the ocean and the many goods and services it provides. However, the ocean is under cumulative stress from various human-driven pressures, leading to eutrophication, deoxygenation, loss of genetic biodiversity, contamination with emerging pollutants (e.g., microplastics and pesticides), and climate change (warming and ocean acidification). The effects of multiple ocean stressors and their interplay on marine life and ecosystems remain poorly understood. This underscores the urgent need for innovative science to resolve the complexity of the interplay of stressors and the resulting impacts. This paper reports findings from the Coordinated Research Project CRP K41018, a five-year program framed by the IAEA. The project was explicitly designed to advance Member States’ understanding of both quantitative and qualitative impacts of ocean acidification on key economically relevant seafood species across different world regions. Furthermore, based on different sensitivity baselines across species, it aimed at exploring adaptation pathways for aquaculture and food industries. As a result, Member States would have improved their comprehension of resilience building in specific local contexts (e.g., types of environments, geographical parameters, human dimension). In this context, it is essential to look for ocean solutions to mitigate adverse impacts on seafood and support adaptation strategies based on nature that can counteract stressors. It is concluded that there is great synergy in planning integrated mitigation and adaptation strategies to multiple stressors in marine ecosystems.
Continue reading ‘Evaluating the impact of ocean acidification on seafood – a global approach’Harpagifer bispinis, but not Patagonotothen tessellata, appears robust to interactive effects of ocean warming and acidification in southern Patagonia
Published 11 April 2025 Science ClosedTags: Antarctic, biological response, fish, laboratory, multiple factors, physiology, temperature
Highlights
- Climate change stressors impaired the thermal physiology of P. tessellata and H. bispinis.
- Their thermal tolerances were more affected by ocean warming than by acidification.
- The interaction of both stressors altered the aerobic scope of P. tessellata.
- H. bispinis appears to be more robust to ocean warming and acidification.
Abstract
Ocean warming and acidification challenge marine ectotherms with rapid, multiple and simultaneous environmental changes. As knowledge of these impacts on fish from the sub-Antarctic is scarce, this study seeks to explore the combined effects of warming and acidification on the thermal and metabolic responses of Patagonotothen tessellata and Harpagifer bispinis, two sympatric notothenioid fish from the Beagle Channel. Juveniles were exposed to present-day and near-future summer temperatures (∼10 and 13 °C) and pCO2 levels (∼500 and 1300 μatm) in a full factorial design. Their critical thermal minimum/maximum (CTmin/CTmax) were assessed and their partial thermal tolerance polygons were estimated. Oxygen consumption rates allowed us to calculate fish’ aerobic scope (AS) as the difference between the standard and maximum metabolic rates (SMR and MMR). The CTmin of both species were affected by temperature, pCO2 level and their interaction, while the CTmax of P. tessellata was affected by both factors and that of H. bispinis, only by temperature. The partial thermal tolerance polygon of P. tessellata significantly decreased with future pCO2 levels, while no changes were observed for H. bispinis. In P. tessellata, SMR and MMR were affected by temperature and pCO2 levels and the AS by their interaction. Conversely, H. bispinis showed no differences in SMR, MMR and AS under different conditions. The increase in SMR and decrease in AS of P. tessellata with future temperatures and pCO2 levels may explain the changes in its thermal tolerance, while for H. bispinis, either the species has a greater capacity to adapt its metabolic response to warming and acidification, or different physiological processes are responsible for the observed changes in its thermal tolerance. Overall, present information could be a valuable tool for forecasting shifts in habitat suitability across the distribution range of both species and other similar fish in the context of climate change.
Continue reading ‘Harpagifer bispinis, but not Patagonotothen tessellata, appears robust to interactive effects of ocean warming and acidification in southern Patagonia’The nasal microbiota of two marine fish species: diversity, community structure, variability and first insights into the impacts of climate change-related stressors
Published 25 February 2025 Science ClosedTags: biological response, BRcommunity, community composition, fish, laboratory, molecular biology, multiple factors, otherprocess, prokaryotes, temperature
Vertebrate nasal microbiota (NM) plays a key role regulating host olfaction, immunity, neuronal differentiation, and structuring the epithelium. However, little is known in fish. This study provides the first comprehensive analysis of the NM in two marine fish species, the European seabass and the Atlantic cod. Given its direct environmental exposure, fish NM is likely influenced by seawater fluctuations. We analysed the community structure, specificity regarding seawater, and interindividual variability of 32 to 38 fish reared under ambient conditions. Additionally, we conducted an experiment to investigate the influence of acidification and a simplified heatwave on cod NM (3 fish per replicate). High-throughput 16S rRNA sequencing revealed species-specific NM communities at the genus-level with Stenotrophomonas and Ralstonia dominating seabass and cod NM, respectively. This suggests potential habitat- or physiology-related adaptations. The most abundant bacterial genera in seabass NM were also present in seawater, suggesting environmental acquisition. Alpha diversity was highest in Brest seabass NM and variability greatest in Tromsø cod NM. Simulated climate change-related scenarios did not significantly alter cod NM structure. We propose a minimum of 13 cod rosettes per replicate for future studies. This research establishes a foundation for understanding marine fish NM and its response to environmental changes.
Continue reading ‘The nasal microbiota of two marine fish species: diversity, community structure, variability and first insights into the impacts of climate change-related stressors’
