Ocean warming is driving species range extensions into cooler regions. The direct physiological influence of warming on species performance can accelerate such extensions into novel ecosystems; however, indirect effects of invader–resident interactions in cooler regions may counter these positive effects. Here, we examined the foraging performance and densities of competing warm‐water and cool‐water fishes across a latitudinal temperature gradient spanning 1500 km from tropical to temperate reefs subjected to rapid ocean warming in the southern hemisphere, and across natural analogs of temperate, tropicalized, and acidified reef localities in the northern hemisphere, and during a severe marine heatwave at a temperate reef. While current levels of ocean warming have allowed the warm‐water fish to extend their ranges into temperate ecosystems at both hemispheres, their foraging performance was reduced at both the cold‐ and warm‐temperate reefs compared to the (sub)tropical reefs. However, at the (warmer) tropicalized reef, the warm‐water fish had higher foraging performance and maintained densities, even under extreme pH reduction, compared to the temperate reef. In contrast, the cool‐water species struggled at the warmer tropicalized and extreme reefs with reduced foraging performance and lower population densities compared to the temperate reef. Contrastingly, the severe heatwave experienced at the temperate reef did not alter the foraging behaviors of either species. We suggest that ocean warming boosts the foraging performance of the range‐extending warm‐water fish and impairs that of their cool‐water competitor at temperate reefs, irrespective of acidification and heatwaves, leading to a shift in dominance hierarchies on temperate reefs. We conclude that warming‐driven increases in foraging performance of the warm‐water species may alleviate foraging limitations and enhance its establishment at its leading range edges under climate change, to the detriment of its cool‐water competitors.
Continue reading ‘Range-extending fish become competitive dominants under ocean warming but not heatwaves or acidification’Posts Tagged 'temperature'
Range-extending fish become competitive dominants under ocean warming but not heatwaves or acidification
Published 27 February 2026 Science Leave a CommentTags: biological response, field, fish, multiple factors, North Pacific, performance, temperature, vents
A standardised experimental setup for simulating ocean warming and acidification in benthic marine invertebrates
Published 26 February 2026 Science Leave a CommentTags: biological response, laboratory, Mediterranean, methods, mollusks, multiple factors, porifera, temperature
Recent studies identify ocean warming and acidification as major drivers of ecological change in the Eastern Mediterranean, posing serious threats to marine biodiversity, particularly for sessile or low-mobility organisms that cannot escape unfavourable conditions. At the same time, the need for standardised experimental approaches capable of generating high-quality data on organismal responses to multiple climate stressors has become increasingly evident. This manuscript presents a fully detailed and replicable experimental framework for simulating ocean warming and acidification in benthic marine invertebrates under controlled laboratory conditions. Detailed protocols include the technical set-up, experimental design, selection of climate scenarios, monitoring procedures and criteria for species selection and demonstrating its application through a validation case study from the MACCIMO project.
Continue reading ‘A standardised experimental setup for simulating ocean warming and acidification in benthic marine invertebrates’Pacific cod gene expression analysis reveals how changing oceans impact larvae
Published 20 February 2026 Press releases ClosedTags: biological response, fish, molecular biology, multiple factors, North Pacific, temperature
A new study used gene expression analysis to explore how temperature and ocean acidification affect Pacific cod larvae. Scientists discovered that larvae are equipped with genes that allow them to survive cool and acidified conditions. However, warming may cause mortality by depleting energy and triggering inflammatory responses. These mechanisms are possible links between changes in ocean conditions and the recruitment of young fish in the Gulf of Alaska Pacific cod population.
Decrease in Pacific Cod Population
Pacific cod is a highly valued commercial fishery, and cod also play a key role in the ecosystem as both predator and prey. However, cod populations in Alaska have declined in recent years. Decreased population size is likely linked to recent marine heat waves, and early life stages seem to be the most impacted. Scientists predict that marine heatwaves may be more common in the future and that ocean acidification will intensify, particularly at high latitudes.
Experiments have shown that Pacific cod are sensitive to temperature during their early life stages. Temperature influences how their eggs develop, how their bodies use energy, and how they grow and survive as larvae. We don’t know as much about the impacts of ocean acidification.
In a 2024 study at the NOAA Fisheries Alaska Fisheries Science Center, scientists raised Pacific cod from embryos to larvae at multiple temperatures (3°C, 6°C, 10°C). To examine the potential interaction between temperature and ocean acidification, they also raised them in water that replicated current ocean conditions and in more acidified conditions. This mimicked conditions projected for the end of this century. The study found that larval mortality was very high in warm water but the effect of acidification was more complex.
The effects of temperature and acidified conditions depended on the fish’s development stage. Scientists need to better understand how changing ocean conditions can affect important species like Pacific cod, and whether these species can adapt to these changes.
A Deeper Dive with Gene Expression
This new molecular study examined larvae to understand why heat wave temperatures might cause larvae to die at high rates. “Finding larvae that are dying in the field is very unlikely, but we were able to sample experimental larvae that we knew were dying rapidly due to warming,” said Emily Slesinger, researcher at NOAA’s Alaska Fisheries Science Center. They also sampled larvae exposed to other conditions. The experiments simulated more acidified water and colder temperatures which Pacific cod larvae currently experience in some regions and years. Slesinger continues, “The unique thing about this study’s approach is to look beyond whether these larvae live or die under different conditions, but to understand why through gene expression analysis.”
Continue reading ‘Pacific cod gene expression analysis reveals how changing oceans impact larvae’Indo-Pacific coral reef sponge diversity declines under predicted future ocean conditions
Published 19 February 2026 Science ClosedTags: abundance, biological response, BRcommunity, community composition, corals, laboratory, mesocosms, multiple factors, North Pacific, otherprocess, porifera, temperature
Future oceans are predicted to favor groups like sponges over calcifying taxa such as scleractinian corals. Here, we test this hypothesis by examining the development of coral reef communities in experimental mesocosms over 23 months. 85 sponge species among the calcifying class Calcarea (~33%), and non-calcifying Demospongiae (~60%) and Homoscleromorpha (<10%) recruited to warming (+2°C), acidification (-0.2 pH), and warming+acidification (+2°C, -0.2 pH) future ocean treatments. The diversity of calcifying sponges was unimpacted across any treatment, whereas non-calcifying classes showed greatest declines. 57-66% of demosponges decreased under future ocean conditions, and homoscleromorphs were entirely absent from acidified treatments. Through the sponge loop, sponges play a fundamental role in coral reef nutrient cycling, and altered coral reef community composition likely has functional consequences. This study challenges the assumption that non-calcifying species are less impacted and highlights the importance of understanding how community composition may alter ecosystem functioning under future ocean conditions.
Continue reading ‘Indo-Pacific coral reef sponge diversity declines under predicted future ocean conditions’Molecular indicators of warming and other climate stressors in larval Pacific cod
Published 19 February 2026 Science ClosedTags: biological response, fish, molecular biology, morphology, multiple factors, North Pacific, reproduction, temperature
Recent marine heatwaves in the Gulf of Alaska negatively impacted Pacific cod (Gadus macrocephalus) through a series of failed year classes and poor recruitment to the fishery. Experimental work by Slesinger et al. (2024) corroborated the hypothesis that warming directly impacts recruitment by increasing larval mortality rates. In this companion study, we applied transcriptomics with larvae from Slesinger et al. (2024) to better understand how warming affected their physiology and identify potential mechanisms contributing to mortality. RNASeq data reveal that warm-exposed larvae have unique gene expression profiles that may reflect high levels of inflammation, lipid dysregulation or depletion, and altered development of visual systems and neurological pathways. Warming may therefore cause a metabolic mismatch whereby energy-demanding activities (development, inflammation, growth) exceed energy production capacity despite access to prey. We also report the less pronounced transcriptional differences in larvae exposed to cold, acidification, and a combination of stressors reflecting future climate scenarios. This information will guide future genetic and experimental work that will ultimately inform recruitment forecasts in years with conditions similar to those tested here.
Continue reading ‘Molecular indicators of warming and other climate stressors in larval Pacific cod’Population-level transcriptomic datasets from two benthic invertebrates exposed to long-term experimental warming and acidification
Published 18 February 2026 Science ClosedTags: biological response, laboratory, Mediterranean, molecular biology, mollusks, multiple factors, porifera, temperature
Ocean warming and acidification are major drivers of change in marine ecosystems, with particularly strong impacts on low-mobility benthic organisms. Despite their ecological importance, genomic and transcriptomic resources for sponges (Phylum: Porifera) and marine gastropods (Phylum Mollusca) that capture responses to long-term, combined climate stressors and population-level variability remain limited. Herein, we present population-level RNA-seq datasets from the sponge Chondrilla nucula and the gastropod Hexaplex trunculus, collected from northern and southern Aegean Sea (Eastern Mediterranean) populations and exposed for three months to elevated temperature and reduced pH in a common garden experiment simulating near-future climate change conditions. The datasets comprise high-quality paired-end Illumina reads, a complete de novo transcriptome assembly for C. nucula, and genome-guided alignments for H. trunculus. These datasets provide a valuable resource for investigating transcriptional plasticity and climate change resilience in benthic marine invertebrates.
Continue reading ‘Population-level transcriptomic datasets from two benthic invertebrates exposed to long-term experimental warming and acidification’Metabolic rate measurements of two benthic invertebrates under simulated climate change conditions
Published 16 February 2026 Science ClosedTags: adaptation, biological response, laboratory, Mediterranean, mollusks, morphology, multiple factors, otherprocess, porifera, respiration, temperature
Climate change is profoundly altering marine ecosystems through ocean warming and acidification. These stressors are especially pronounced in the Mediterranean Sea, a climate change hotspot projected to warm faster than the global average. Increased temperatures and reduced pH directly affect metabolic processes in marine invertebrates by elevating respiration rates up to species-specific thermal limits, beyond which physiological performance declines. Ocean acidification further disrupts metabolic processes by increasing energetic maintenance costs. Sessile and sedentary marine invertebrates, such as sponges and benthic gastropods, are particularly exposed to such environmental shifts due to their limited ability to escape unfavorable conditions, making physiological plasticity and local adaptation crucial for persistence.
This manuscript presents a dataset of oxygen consumption rates and wet weight measurements for two low-mobility marine species, the gastropod Hexaplex trunculus and the sponge Chondrilla nucula. Using a common garden experiment, individuals from North and South Aegean populations were exposed for three months to simulated climate change conditions combining increased temperature and reduced pH. The dataset documents respiration measurements obtained using metabolic chambers after three months of exposure, allowing comparisons across species, geographic origin, and experimental treatments.The dataset accounts for intraspecific variation in these responses, providing insight into potential adaptive differences among geographically distinct populations. These data provide a resource for future analyses of metabolic responses of marine invertebrates to combined warming and acidification conditions.
Continue reading ‘Metabolic rate measurements of two benthic invertebrates under simulated climate change conditions’Acute microbial and nutrient responses to elevated temperature and pCO2: a coastal UK microcosm study
Published 13 February 2026 Science ClosedTags: abundance, biogeochemistry, community composition, laboratory, multiple factors, North Atlantic, nutrients, otherprocess, phytoplankton, temperature
The coastal ocean’s ecosystem resilience is consistently hampered by the compounding impacts of projected climate change and anthropogenic perturbation. In this microcosm study, we investigated how elevated temperature and pCO2, together with episodic nutrient pollution and a short-term marine heatwave, affect the nano- and picoplanktonic community of primary producers and subsequent changes in coastal biogeochemistry. Our study demonstrates that future elevated temperature and pCO2 conditions impact the planktonic community, first by a ∼ 50 % decreased autotrophic abundance, and second by a shift from larger eukaryotic to smaller cells. When combined with a heatwave, total primary producers experienced an additional 37–38 % decrease, indicative of a negative synergistic effect beyond either stressor alone. Picoeukaryotes were particularly sensitive, declining by 44–50 %. Short-term nutrient pollution under ambient conditions induced a 41 % increase in cell abundance, but failed to stimulate biomass under elevated temperature and pCO2, and instead led to altered organic matter dynamics, including significantly lower carbon fixation. These findings emphasize the need for further evaluation of multi-stressor interactions to better understand biogeochemical vulnerability, nutrient retention, and ecological functioning in coastal ecosystems undergoing rapid climatic and anthropogenic change.
Continue reading ‘Acute microbial and nutrient responses to elevated temperature and pCO2: a coastal UK microcosm study’Experimental exposure to climate change scenarios imposed alterations on the morphological traits of sessile and low-motility marine invertebrates
Published 6 February 2026 Science ClosedTags: biological response, laboratory, Mediterranean, methods, mollusks, morphology, multiple factors, porifera, temperature
Over the past 50 years, the oceans have absorbed over 90% of global warming heat, leading to warming, acidification, and declining oxygen levels that are disrupting marine ecosystems and altering species distributions and productivity. The vulnerability of marine organisms to these changes depends on their biological traits, habitat conditions, and adaptive capacity, influencing their growth, behavior, and overall population health. Micro-computed tomography (micro-CT) has been previously used for studying the morphological traits of marine invertebrates, which provide important insights into species functionality and responses to climate change and ocean acidification. Micro-CT enables non-destructive, high-resolution 3D analysis of internal and external structures, allowing precise measurement of traits such as density, porosity, and morphology that are valuable for climate change research.
The present manuscript describes micro-CT imaging datasets generated to investigate the effects of climate change on the morphological structure of two low-motility benthic marine invertebrates: the gastropod Hexaplex trunculus and the sponge Chondrilla nucula. Both species are considered particularly vulnerable to environmental stressors. To date, no study has investigated the effects of ocean warming and acidification on sponges using micro-CT technology. Using a common garden experimental design, individuals from geographically distinct populations exposed to different natural environmental regimes were subjected to combined warming and acidification scenarios to assess their morphological responses and adaptive capacity.
Continue reading ‘Experimental exposure to climate change scenarios imposed alterations on the morphological traits of sessile and low-motility marine invertebrates’Triple threat: ocean acidification, warming, and hyposalinity synergistically weaken shell integrity in a Mediterranean calcifying mollusk
Published 30 January 2026 Science ClosedTags: biological response, fisheries, laboratory, Mediterranean, mollusks, morphology, mortality, multiple factors, salinity, temperature
Highlights
- OA, OW, and hyposalinity drive skeletal and mineralogical responses in a Mediterranean clam.
- Combined stress makes shells less dense, more porous, and more fracture-prone.
- Microstructural changes reveal early calcification impairments under triple stress.
- Triple-stressor synergy compromises shell integrity and threatens fishery species resilience.
Abstract
Anthropogenic climate change is rapidly altering marine environments primarily through ocean warming, acidification, and hyposalinity, posing significant challenges for marine calcifying organisms. This study investigated the short-term effects of these stressors on the Mediterranean bivalve Chamelea gallina, a key fishery species in the Adriatic Sea, by integrating skeletal, mechanical, and mineralogical responses. Adult clams of commercial size were exposed for 21 days to eight experimental treatments manipulating two levels of temperature (18 °C vs. 22 °C), pH (8.0 vs. 7.9), and salinity (35 vs. 32), chosen to reproduce near-future climate projections and the freshwater-driven variability typical of the Adriatic Sea. Despite the short exposure duration, the combined exposure to low pH, high temperature, and reduced salinity weakens the shell of Chamelea gallina at multiple levels, compromising shell integrity, by making shells less dense, more porous, more fragile, and more susceptible to fracture, and increasing mortality. Microstructural analysis revealed smaller aragonite crystallites and lower calcium content, indicative of early impairments in the calcification process. The study highlights the occurrence of synergistic effects among stressors and reveals the vulnerability of Chamelea gallina to near-future ocean conditions, with potential cascading consequences for ecosystem functioning and fishery sustainability, given the species’ key ecological role and commercial relevance in the Adriatic Sea.
Continue reading ‘Triple threat: ocean acidification, warming, and hyposalinity synergistically weaken shell integrity in a Mediterranean calcifying mollusk’Transgenerational effects of extreme weather on Manila clam resilience: implications for aquaculture sustainability
Published 27 January 2026 Science ClosedTags: adaptation, biological response, fisheries, laboratory, mollusks, morphology, mortality, multiple factors, North Pacific, otherprocess, physiology, reproduction, respiration, temperature
Highlights
- SAE+MHW synergistically impaired clams during reproduction.
- Progeny exhibited lasting developmental delays and high mortality.
- Long-term physiological dysfunction persisted into later life stages.
- Compound extremes threaten bivalve aquaculture resilience.
Abstract
Extreme environmental events, including sea acidity extremes (SAE) and marine heatwaves (MHW), pose increasing threats to coastal aquaculture species. This study examined the individual and combined effects of SAE and MHW on Manila clams (Ruditapes philippinarum) and their transgenerational impacts. Adults exposed to SAE+MHW showed reduced survival, decreased condition index, lower clearance rate (CR) and assimilation efficiency (AE), elevated ammonia excretion (ER), and negative scope for growth, indicating disrupted energy budgets. Reproductive output and gonadal development were also compromised. Offspring from stressed parents exhibited lower larval survival, stunted shell growth, reduced metamorphic success, smaller settlement size, reduced juvenile (6-month-old) survival rate and disrupted energy homeostasis, revealing persistent transgenerational impacts on development and energy homeostasis. These findings suggest that parental exposure to synergistic SAE+MHW alters energy allocation and may involve epigenetic mechanisms, ultimately impairing offspring fitness. Overall, our study demonstrates that compound extreme events can severely affect metabolic resilience and cross-generational performance in Manila clams, highlighting the need for multigenerational assessments, selective breeding, and aquaculture strategies to enhance climate resilience.
Continue reading ‘Transgenerational effects of extreme weather on Manila clam resilience: implications for aquaculture sustainability’An experimental approach to study climate change stress in benthic marine invertebrates
Published 26 January 2026 Science ClosedTags: biological response, laboratory, Mediterranean, methods, mollusks, multiple factors, porifera, temperature
Climate change is altering ocean temperature and chemistry, with ocean warming and acidification posing serious threats to marine biodiversity, particularly for sessile or low-mobility organisms that cannot escape unfavorable conditions. The MACCIMO project investigated the effects of these stressors on the sponge Chondrilla nucula and the gastropod Hexaplex trunculus using an integrative approach that examined molecular, physiological, morphological, and symbiotic responses. By applying a common garden experiment to populations from different Mediterranean regions, the study aimed to distinguish genetic and environmental influences on stress tolerance and assess intraspecific variability. Three experimental scenarios were simulated, including a control treatment and two climate change treatments based on the “high GHG emissions” RCP 8.5 scenario. A semi-enclosed experimental system with precise control of temperature and pH was designed which can be easily replicated to support laboratory studies on the effects of climate change and ocean acidification on small marine invertebrates across multiple biological levels.
Continue reading ‘An experimental approach to study climate change stress in benthic marine invertebrates’Northern shrimp exhibit origin-specific proteomic remodelling under ocean acidification, with limited response to ocean warming
Published 19 January 2026 Science ClosedTags: adaptation, biological response, crustaceans, laboratory, multiple factors, North Atlantic, otherprocess, physiology, temperature
Highlights
- Ocean acidification, but not warming, drives proteomic response in Northern Shrimp.
- Shrimp from different origins show distinct molecular responses to ocean acidification.
- St. Lawrence shrimp display the strongest protein changes to ocean acidification.
- Local conditions shape how shrimp cope with global change drivers.
- Conservation plans must consider regional differences in shrimp responses.
Abstract
The Northern shrimp (Pandalus borealis) is an ecologically important species and the target of one of the world’Canas largest shellfish fisheries. Yet, its habitats are rapidly changing due to human-driven climate change, with temperatures projected to increase by ∼4 °C and seawater pH to decline by 0.3 pH units the end of the century. These stressors may cause interactive effects, with responses differing among origins due to local adaptation or long-term acclimatisation. We investigated the impacts of ocean warming and acidification (individually and combined) on the proteome of female P. borealis from four geographic origins. Shrimp proteomes responded to ocean acidification, but not to warming, with marked origin-specific differences. Comparing the most favourable condition (2 °C, pH 7.75) to low pH (7.35) across tested temperatures, we detected 109 differentially abundant proteins (DAPs) in shrimp from the Saint Lawrence Estuary (SLE), six in those from the Northeast Newfoundland Coast (NNC) and Eastern Scotian Shelf (ESS), and three in the Esquiman Channel (EC). SLE shrimp showed widespread downregulation across metabolic, genetic information processing, and signalling pathways, suggesting higher sensitivity to acidification relative to other origins, where responses were muted. These findings highlight intraspecific variation in proteomic responses to ocean acidification in this commercially valuable crustacean. They confirm ocean acidification as a major concern in the context of rapid environmental change and suggest that uniform conservation strategies may be ineffective. Instead, management efforts should account for origin-specific sensitivities, reflecting the complex adaptive landscape shaping the resilience of P. borealis and other exploited marine species.
Continue reading ‘Northern shrimp exhibit origin-specific proteomic remodelling under ocean acidification, with limited response to ocean warming’An indoor mesocosm system for cost-effective simulation of multiple ocean stressors affecting marine organisms
Published 16 January 2026 Science ClosedTags: laboratory, methods, multiple factors, oxygen, temperature
Global climate change is exacerbating multiple ocean stressors, including ocean acidification (OA), ocean warming (OW), and deoxygenation (deOxy), which collectively threaten marine ecosystems and fisheries. Understanding how these stressors interact to shape organismal and ecosystem responses is increasingly critical, yet it remains technically challenging and expensive to simulate them concurrently under controlled indoor conditions. To address this limitation, we developed a closed indoor mesocosm system that enables stable and long-term simulation of these three stressors for biological and aquaculture research. The system maintains consistent levels of CO2, temperature, and dissolved oxygen (DO) over multi-month experiments without automated control units, relying instead on robust initial settings. High-purity CO2 and N2 gases are blended with ambient air in controlled ratios to regulate carbonate chemistry and oxygen levels, while chillers and heaters ensure precise temperature control. Validation experiments demonstrated that the system can (1) increase pCO2 to approximately twice the present-day level with a pH reduction of ~ 0.22 units, (2) elevate temperature by + 3 °C above ambient temperature, and (3) reduce DO by up to 40% relative to ambient concentration, reflecting projected climate scenarios. This simple and versatile mesocosm provides a practical platform for investigating the ecophysiological responses of marine organisms under multi-stressor environments, supporting research on climate adaptation and aquaculture resilience.
Continue reading ‘An indoor mesocosm system for cost-effective simulation of multiple ocean stressors affecting marine organisms’Integrated biochemical profiling, comparative transcriptome and weighted gene co-expression network analysis to explore the response mechanism of global warming and ocean acidification to the stress of Sepia esculenta larvae
Published 16 January 2026 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, multiple factors, North Pacific, physiology, reproduction, temperature
Highlights
- Multi-angle analysis of Sepia esculenta under global warming and ocean acidification.
- Stress enhanced the immune defense and antioxidant defense of S.esculenta.
- The hub genes closely related to stress resistance were identified and screened out.
- Provided a theoretical basis for the breeding of fine varieties and pond culture.
Abstract
The Sepia esculenta has high economic value and nutritional value, and accounts for a high proportion of the catch of cephalopods in China ‘s coastal waters. Global warming and ocean acidification, as major environmental problems currently facing the world, have a serious negative influence on the survival and breeding of S. esculenta. Therefore, in the research, transcriptome sequencing and biochemical quantitative analysis were performed on the larvae of S. esculenta after high temperature, low pH and combined stress at different time points, and the differential expressed genes (DEGs) and response mechanisms were identified. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that these DEGs were mainly involved in a large number of immune-related biological processes and signaling pathways, including Immune response、Phagocytosis、Regulation of DNA-templated transcription and Positive regulation of DNA-templated transcription. Then, we further explored the functional relationship between these DEGs by constructing weighted gene co-expression network and protein-protein interaction networks. We identified ten hub genes including HSP90AA1, ALDH1L1, VPS13A, MAPK8IP1 and KDM6A. These hub genes may play an important role in the face of high temperature, low pH and their combined stress at different times. Our findings not only elucidate the molecular response mechanisms of S. esculenta to environmental stress and delineate the key regulatory pathways underlying its adaptation, but also provide a theoretical foundation for advancing pond cultivation.
Continue reading ‘Integrated biochemical profiling, comparative transcriptome and weighted gene co-expression network analysis to explore the response mechanism of global warming and ocean acidification to the stress of Sepia esculenta larvae’Assessing impacts of extreme climate and weather events on endangered pearl oysters Pinctada maxima
Published 13 January 2026 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, multiple factors, North Pacific, physiology, reproduction, temperature
Extreme climate and weather events in the ocean, especially ocean acidification (OA) and marine heatwaves (MHWs), have strikingly accelerated in the past decades, yet their compound consequences remain poorly understood. The pearl oyster (Pinctada maxima), an endangered keystone species in Indo-Pacific reef ecosystems, is highly vulnerable to such events. Here, we assessed how OA-stressed P. maxima juveniles responded to MHWs (+3 °C), based on a total of 100 individuals exposed to two weeks. Oysters reared at pH 7.7 significantly increased activities of energy-metabolizing enzymes (T-ATP and NKA) in response to MHWs, whereas both enzymes significantly decreased, albeit CMA increased, at pH 7.4. MHWs significantly depressed antioxidant enzyme activities, such as SOD at both pH levels, resulting in elevated MDA levels indicative of lipid peroxidation. Contrasting responses of immune enzymes (ACP and AKP) to MHWs were seen in oysters grown under moderately and severely acidified conditions. MHWs, also, significantly depressed expression levels of key genes related to cellular metabolism (ATP1A, ATP1B, ND5, ATPeV1F and ATPeF1A) and those associated with antioxidant defence (SOD, SOD1, SOD2, Hsp70, Hsp90 and CAT), in particular when stressed at pH 7.4. Taken together, our findings suggest that intensifying MHWs can constrain the ability of P. maxima to cope with OA and likely accelerate further population decline in this era of unprecedented climate change.
Continue reading ‘Assessing impacts of extreme climate and weather events on endangered pearl oysters Pinctada maxima’Physiological and transcriptomic responses of a harmful algal bloom-causing dinoflagellate Karenia mikimotoi to multiple environmental factors
Published 12 January 2026 Science ClosedTags: biological response, growth, laboratory, molecular biology, multiple factors, North Pacific, nutrients, photosynthesis, physiology, phytoplankton, temperature
Highlights
- Elevated temperature was the primary factor significantly reducing K. mikimotoi growth and photosynthesis.
- Increased pCO₂ and high N: P ratios partially mitigated thermal stress induced by elevated temperature.
- K. mikimotoi consistently up-regulated energy and lipid metabolism to cope with environmental stressors irrespective of treatment.
- K. mikimotoi may persist and even thrive under multiple stressors, subsequently influencing productivity and biogeochemical cycles.
Abstract
Dinoflagellates play a crucial role in marine food webs and biogeochemical cycles, yet they are increasingly affected by global environmental changes. While there is limited understanding of their response to individual stressors projected under future oceanic conditions, their response to multiple concurrent environmental stressors remains inadequately explored. This study investigated the singular and interactive effects of elevated temperature (26 °C vs. 22 °C), increased pCO2 (1000 μatm vs. 400 μatm), and a high nitrogen-to-phosphorus ratio (N:P = 180:1 vs. 40:1) on the harmful algal bloom-forming dinoflagellate Karenia mikimotoi over a 40-day exposure period. Among these factors, elevated temperature exerted the most pronounced influence, markedly reducing the cell growth rate and photosynthesis while simultaneously increasing the particulate organic matter content and antioxidant level. Transcriptomic analyses indicated that elevated temperature enhanced the expression of genes associated with oxidative stress, suggesting a potential defense mechanism against thermal stress. Notably, increased pCO2 and a high N:P ratio appeared to mitigate thermal stress to some extent. Irrespective of the treatment, K. mikimotoi demonstrated a consistent response strategy characterized by the synergistic upregulation of energy metabolism and lipid biosynthesis pathways, coordinated by the modulation of both upstream and downstream genes in the tricarboxylic acid cycle. This metabolic reprogramming likely facilitates a more efficient allocation of energy, thereby enhancing the resilience of K. mikimotoi to environmental stress. This study underscores the interactive effects of multiple stressors on marine dinoflagellates, highlighting that elevated temperature is the most critical factor affecting dinoflagellates in future oceanic environments.
Continue reading ‘Physiological and transcriptomic responses of a harmful algal bloom-causing dinoflagellate Karenia mikimotoi to multiple environmental factors’Combined effects of ocean acidification, warming, and salinity on the fertilization success in an Arctic population of sea urchins
Published 9 January 2026 Science ClosedTags: Arctic, biological response, echinoderms, laboratory, multiple factors, reproduction, salinity, temperature
Anthropogenic stressors, including ocean acidification (OA), ocean warming (OW), and salinity changes, are rapidly altering marine ecosystems, with Arctic regions being particularly vulnerable. This study investigates the combined effects of these stressors on the fertilization success of the green sea urchin (Strongylocentrotus droebachiensis) from Kongsfjorden, Svalbard. We exposed gametes to various levels of pH, temperature, and salinity to assess their individual and combined impacts on fertilization performance. Our results show that temperature and pH significantly influenced fertilization success, with temperature having the strongest effect, while salinity had no significant impact. A significant statistical interaction between temperature and pH indicated that warming enhanced fertilization more effectively at higher pH levels, while low pH suppressed this increase. To compare the relative influence of each stressor, we used a conceptual model based on standardized slopes, which supported temperature as the dominant driver, followed by pH. These findings highlight the importance of considering the effects of combined stressors when assessing marine organism responses to climate change, especially in polar ecosystems. Our study underscores the need for further research into the mechanisms driving these combined effects, given that Arctic ecosystems face accelerated environmental changes.
Continue reading ‘Combined effects of ocean acidification, warming, and salinity on the fertilization success in an Arctic population of sea urchins’Modeling the spatiotemporal effects of ocean acidification and warming on Atlantic sea scallop growth to guide adaptive fisheries management
Published 7 January 2026 Science ClosedTags: biological response, communitymodeling, fisheries, modeling, mollusks, morphology, multiple factors, North Atlantic, temperature
Highlights
- We spatially couple a scallop bioenergetic model to a regional oceanographic model.
- Our model reproduces observed growth patterns using temperature, food, and pCO2.
- Mid-century warming enhances scallop growth except in the south.
- By 2100, scallops grow faster but reach smaller sizes under warming and acidification.
- This tool can inform adaptive fisheries management under climate change.
Abstract
Climate-ready fisheries management requires reliable predictions of species responses to changing conditions across large-scale environmental gradients. Bioenergetic frameworks, such as Dynamic Energy Budget (DEB) models, relate physiological processes to environmental conditions, enabling predictions of organismal growth under projected climate change conditions. Here, we provide the first large-scale coupling of a DEB model to downscaled regional oceanographic simulations to resolve spatiotemporal changes and reveal how climate stressors emerge at relevant biogeographic, economic, and oceanographic scales. We calibrated our DEB model for the Atlantic sea scallop (Placopecten magellanicus) with forcing from a realistic oceanographic and biogeochemical model for the Northeast U.S. continental shelf to predict the effects of ocean acidification (OA) and warming on individual growth historically and over the next century. Our model reproduced observed historical patterns in scallop age at harvest size and maximum size. At mid-century (2035–2050), scallop growth was projected to increase in most areas except the southern Mid-Atlantic, and OA effects were limited to the deep Gulf of Maine. By the end of the century (2080–2095) under a high emissions scenario, scallops were predicted to grow faster but attain smaller maximum sizes. Our results highlight that warming stress is more acute than previously accounted for, particularly in the southern Mid-Atlantic. While warming stress emerges in the south first, OA stress emerges before warming in the north. Together, these emerging stressors compress the spatial range for optimal growth. Altogether, our findings demonstrate the utility of the spatially coupled DEB model as a tool to inform adaptive fisheries management.
Continue reading ‘Modeling the spatiotemporal effects of ocean acidification and warming on Atlantic sea scallop growth to guide adaptive fisheries management’Reproduction of the viviparous marine isopod Cirolana harfordi held in seawater with raised temperature and lowered pH
Published 2 January 2026 Science ClosedTags: biological response, crustaceans, growth, laboratory, mortality, multiple factors, reproduction, temperature, zooplankton
Cirolanid isopods play important ecological roles as predators and scavengers, but when populations increase, they can form swarms that attack fish and humans. Understanding how the reproduction of cirolanid isopods will be affected by future warmer and more acidic oceans is therefore important. Samples of the viviparous species Cirolana harfordi were held in 4 combinations of 2 temperatures (18 and 24°C) and 2 pH levels (7.7 and 8.1), and the development of embryos and mancas was investigated by microscopic examination of each pregnant female through the transparent ventral cuticle of their thorax. Higher temperature increased the rate of development, thereby reducing pregnancy duration and accelerating the growth of mancas postpartum. By contrast, increased acidity had no significant effect on these parameters and had no deleterious effects on the development of the mancas. Higher temperature did not have a significant effect on the number of postpartum mancas after the 22 weeks that the adults spent in treatments. Increased temperature and/or lowered pH had no effect on the adult survival or growth. These data are in keeping with the hypothesis that C. harfordi may be able to withstand future warmer and more acidic oceans. Longer-term studies are needed to determine whether decreasing pregnancy durations in higher temperatures increases the number of times females can become pregnant over their lifetime, potentially leading to greater population numbers.
Continue reading ‘Reproduction of the viviparous marine isopod Cirolana harfordi held in seawater with raised temperature and lowered pH’
