Climate change, contaminant exposure, and emerging disease dynamics are increasingly recognized as interconnected stressors affecting marine crustaceans, including lobsters. This review compares three commercially and ecologically important species: Homarus americanus, Homarus gammarus, and Jasus edwardsii. Although these species differ taxonomically and ecologically, environmental stressors rarely act in isolation; climate change and contaminants interact to modify metabolic performance, molting, microbial dynamics and pathogen susceptibility. By synthesizing existing literature, this review identifies shared vulnerabilities and species-specific responses. Evidence suggests differences in thermal tolerance, developmental sensitivity and physiological plasticity, with early life stages consistently representing the most sensitive period across species. The American lobster has the strongest evidence linking warming waters to physiological stress and disease prevalence, particularly in Southern New England, whereas extensive research for European and Southern Rock lobsters remain limited. Across species, warming and ocean acidification often interact with contaminant exposure to alter immune function, molting, and recruitment. Key gaps remain in multi-stressor experiments, disease ecology and early life-stage research, emphasizing the need for integrative multi-stressor and cross-species frameworks to improve predictions of lobster resilience under accelerating environmental change.
Continue reading ‘A review: climate, contaminants and disease dynamics in lobster species Homarus americanus, Homarus gammarus and Jasus edwardsii’Posts Tagged 'North Atlantic'
Putting a time scale on emerging climate change stressors: a vulnerability index for Atlantic Ocean marine ecosystem services
Published 2 November 2026 Science Leave a CommentTags: chemistry, modeling, multiple factors, North Atlantic, oxygen, policy, regionalmodeling, socio-economy, South Atlantic, temperature
Highlights
- Climate stressor emergence is highly heterogeneous across the Atlantic.
- Multi-stressor emergence before 2100 is projected for all Atlantic EEZs.
- Vulnerability is driven by emerging climate stressors, amplified by a high sensitivity of habitats and communities, and a low adaptive capacity.
- Lower vulnerability is partly driven by robust governance and infrastructure.
- Adaptive responses must address socio-economic differences and variable exposure to stressors.
Abstract
Marine ecosystem services underpin human wellbeing and support resilient socio-ecological systems, yet existing vulnerability assessments remain fragmented, often focusing on isolated industries and overlooking the whole-system socio-ecological context. To bridge this gap, we develop a comprehensive Vulnerability Index to assess marine ecosystem service vulnerability to emerging climate stressors in the Atlantic. Using high-resolution ocean simulations and moving beyond traditional long-term projections, we employ the Time of Emergence metric to address actionable decision-making timescales (2–3 decades). We found that all Atlantic marine ecosystem services are projected to be exposed to multiple emerging stressors before 2100, though the sequence and the timing of emergence are highly heterogenous. Overall vulnerability is highest in tropical West Africa due to the early emergence of hypoxia and sea level rise extremes compound by low adaptive capacity. Additional hotspots are found in subpolar and polar regions driven by rapid sea ice retreat and the sensitivities of region-specific habitats alongside a high dependence on marine ecosystems. Coupled with socio-ecological data, we determined which services (provisioning, regulatory and cultural) are most sensitive to potential impacts in each EEZ. We anticipate this index to be a starting point to develop targeted vulnerability indices for specific ecosystem services and regions. Mitigative and adaptive efforts must be multi-scale and tailored to national and local contexts, addressing not only socio-economic differences but also variable climate stressors and their impacts. Uncertainties associated with time series data gaps and indicator aggregation, particularly for island and remote territories, highlight the need for targeted national adaptation.
Continue reading ‘Putting a time scale on emerging climate change stressors: a vulnerability index for Atlantic Ocean marine ecosystem services’Tolerance measured at one developmental stage mispredicts climate resilience in an animal with a complex life cycle
Published 2 November 2026 Science Leave a CommentTags: adaptation, biological response, dissolution, growth, laboratory, mollusks, morphology, mortality, North Atlantic, otherprocess, physiology, reproduction
Forecasts of whether marine species can evolve fast enough to survive climate change rely largely on single-stage tolerance assays, tacitly assuming that tolerance measured at one developmental stage reflects adaptive capacity across the organism’s life cycle. We test this assumption in a common marine bivalve (Mercenaria mercenaria) and find that it fails in sign, not degree: larval and post-metamorphic tolerance to end-century ocean acidification are strongly negatively correlated (r = −0.53, 95% CI [−0.69, −0.33]) across family-level, pedigree-conditioned and animal model estimates, with pervasive rank reversals among the top performers of each stage. A multivariate analysis of the among-family covariance matrix G shows why: under acidification, 57% of the among-family variance collapses onto a single dominant axis that loads positively on every larval trait and negatively on every post-metamorphic trait, whereas under ambient conditions the same families show no cross-stage covariance at all. Acidification therefore does not merely depress performance—it reorganizes the genetic architecture into a cross-stage conflict. Under ramping RCP 8.5 forcing this conflict geometry dictates the direction—not merely the magnitude—of adaptation: only balanced multi-stage selection preserves family diversity, whereas single-stage selection systematically erodes the opposite axis. In complex life cycles, resilience is a geometric property of ontogeny that forecasts cannot compress into a single-stage without inverting the sign of the answer.
Continue reading ‘Tolerance measured at one developmental stage mispredicts climate resilience in an animal with a complex life cycle’Spatiotemporal water quality dynamics in Southern U.S. coastal reserves: a long-term perspective
Published 30 October 2026 Science Leave a CommentTags: biogeochemistry, chemistry, field, North Atlantic
Water quality monitoring in estuarine ecosystems is essential for assessing the health and sustainability of these dynamic coastal habitats, which are increasingly vulnerable to environmental change and human impacts. This study aims to characterize long-term trends and seasonal drivers of seven key water quality parameters: temperature, salinity, dissolved oxygen (DO), pH, chlorophyll-a (Chla), nitrate + nitrite (NOx), and phosphate (PO4) across four southern U.S. National Estuarine Research Reserves (Apalachicola Bay, Grand Bay, Mission-Aransas, and Weeks Bay) to identify which reserves and processes are most vulnerable to climate and anthropogenic change. Using two decades of data (1995–2020) and applying Generalized Additive Models (GAMs), we identified significant spatial and temporal patterns linked to environmental and anthropogenic factors. Results revealed a warming trend in Weeks Bay (+0.1035 °C/year, P = 0.0013), a salinity decline in Grand Bay (−0.1699 PSU/year, P = 0.033), and a salinity increase in Apalachicola Bay (+0.2055 PSU/year, P = 0.003). DO concentrations peaked in spring and dropped in summer, reflecting seasonal nutrient inputs. Grand Bay exhibited the highest Chla variability (CV=131.48%). NOx concentrations declined in Grand Bay (−0.0003 mg/L/year, P = 0.0162), while PO4 levels remained relatively stable. pH trends suggested localized acidification, particularly in Mission-Aransas (−0.0071/year, P = 0.0016). GAM results emphasized the combined effects of long-term and seasonal changes, with site-specific differences. These findings provide critical insights into estuarine functioning and highlight the need for regionally tailored management strategies to enhance resilience and biodiversity conservation in U.S. coastal reserves.
Continue reading ‘Spatiotemporal water quality dynamics in Southern U.S. coastal reserves: a long-term perspective’The spatial and temporal variability of dissolved inorganic carbon and total alkalinity production during early diagenesis in river dominated ocean margin sediments and their resultant effect on bottom water acidification
Published 30 October 2026 Science Leave a CommentTags: biogeochemistry, chemistry, field, Mediterranean, North Atlantic, sediment
Rapid anthropogenic release of CO2(g) to the atmosphere promotes global ocean acidification that is exacerbated in coastal environments by processes such as eutrophication and upwelling of low pH deep water. The decline in ocean pH through time poses a threat to marine ecosystems and the coastal communities that depend on them. Total alkalinity (TA), mainly supplied to the ocean by river discharge, allows seawater to buffer against future pH decline. Pore water DIC and TA generated in sediments during early diagenesis may be released to the overlying waters and either contribute to acidity or buffer against overlying water acidity, depending on the benthic TA to dissolved inorganic carbon (DIC) flux ratio (RTA:DIC), as RTA:DIC < 1 promotes acidification and RTA:DIC > 1 mitigates further acidification. The rapid accumulation of organic matter in river dominated ocean margin (RiOMar) sediments promotes the generation of relatively large benthic DIC and TA fluxes that may significantly influence overlying water acidification in these regions. A number of seasonally variable environmental factors such as river discharge and sediment resuspension may promote early diagenetic redox cycling in RiOMar sediments and induce seasonal RTA:DIC variability. This seasonal RTA:DIC variability is poorly characterized, however, despite their potential influence on overlying water acidification in these regions.
The present dissertation investigated how early diagenetic processes in RiOMar sediments and resultant benthic solute fluxes and RTA:DIC respond to seasonally variable environmental factors. This was accomplished using a combination of in-situ benthic flux measurements on the northern Gulf of Mexico (nGoM) continental margin and ex-situ sediment core solid phase and pore water analyses from both nGoM margin and Rhône River prodelta sediments. Overall, the results presented in this dissertation revealed significant seasonal early diagenetic and RTA:DIC variability in RiOMars that was driven by seasonally variable environmental factors such as river discharge, primary production, sediment perturbations, and bottom water hypoxia development. The largest RTA:DIC from RiOMar sediments may be promoted either 1) proximal to river deltas and in eutrophic hypoxic systems, where anerobic TA generation is high and reoxidation of reduced metabolites is low, or 2) when CaCO3 dissolution generates significant TA in pore waters.
Continue reading ‘The spatial and temporal variability of dissolved inorganic carbon and total alkalinity production during early diagenesis in river dominated ocean margin sediments and their resultant effect on bottom water acidification’Physiological responses of Atlantic surfclams (Spisula solidissima) to moderate ocean acidification across thermal regimes
Published 23 October 2026 Science ClosedTags: biological response, chemistry, fisheries, growth, laboratory, mollusks, morphology, multiple factors, North Atlantic, performance, physiology, respiration, temperature
Highlights
- Interactive effects of warming and acidification tested in surfclams.
- Growth, feeding, and metabolic rates measured after 6-week exposure.
- Moderate acidification had limited effects under warming conditions.
- Surfclams showed resilience to near-future ocean acidification.
- Multi-stressor design improves ecological relevance of lab studies.
Abstract
Understanding marine organismal responses to co-occurring climate stressors is critical for predicting changes in ecosystems and commercial fisheries. The Atlantic surfclam supports a major commercial fishery in the Northeastern United States, where ocean warming and acidification are rapidly altering marine habitats. To evaluate how changing ocean conditions may affect bivalve physiology, surfclams were exposed to conditions reflective of ocean warming and acidification, respectively. One-year-old surfclams were exposed to nine conditions in a fully crossed design of temperature (ambient, +2 °C, and + 5 °C) and pH (7.88 ± 0.05, 7.76 ± 0.05, and 7.51 ± 0.07) for six weeks in a flow-through laboratory experiment using natural seawater. We quantified several physiological responses including growth, feeding, digestion, respiration rates, and shell weight and thickness to assess organismal performance across treatments.
Surfclams generally exhibited resistance to moderate ocean acidification across warming, but non-thermally stressful, temperatures. No effects of ocean acidification were observed on surfclam growth or respiration, although other physiological metrics (shell thickness and absorption rate) decreased with decreasing pH at some temperatures. These findings provide experimentally-derived insight into species-specific responses to interacting climate stressors. Further, the experimental design highlights the importance of integrating natural environmental variability into laboratory studies and studying multiple environmental stressors concurrently. This study contributes a basis for refining models of surfclam growth and distribution in potential future climate scenarios, with implications for sustainable fisheries management.
Continue reading ‘Physiological responses of Atlantic surfclams (Spisula solidissima) to moderate ocean acidification across thermal regimes’Seasonal prediction of ocean biogeochemistry in the northeast U.S. large marine ecosystem using a regional ocean-biogeochemistry model
Published 20 October 2026 Science ClosedTags: biogeochemistry, chemistry, modeling, North Atlantic, regionalmodeling
We couple an ocean biogeochemical model to a regional ocean model of the Northwest Atlantic and assess the potential skill of bottom dissolved oxygen, aragonite saturation state, and pH forecasts along the Northeast U.S. Continental Shelf using a reanalysis-forced model run as the true biogeochemical state. Across 30 years of retrospective forecasts initialized four times per year, the model has substantial potential skill for all three variables, with skill generally highest in the deep Gulf of Maine and lowest in the shallower Mid-Atlantic Bight and Georges Bank. Forecasts initialized in January and April benefit from the insulation of the bottom from the unpredictable atmosphere by stratification and tend to have greater skill at longer lead times. Using two case studies, we show how predictable variations in ocean temperature, salinity, and currents are associated with predictable variability in bottom biogeochemistry in both the Mid-Atlantic Bight and Gulf of Maine. The forecast model evaluated in this study has been developed as an operational prototype for NOAA’s Changing Ecosystems and Fisheries Initiative, with the goal of applying the forecasts to improve the yield and sustainability of living marine resources.
Continue reading ‘Seasonal prediction of ocean biogeochemistry in the northeast U.S. large marine ecosystem using a regional ocean-biogeochemistry model’Ocean acidification in the Northwestern gulf of America
Published 19 October 2026 Science ClosedTags: chemistry, field, modeling, North Atlantic, regionalmodeling
The physical and chemical oceanographic properties of the Gulf of Mexico (GOM, recognized by the United States as the Gulf of America) remain incompletely characterized. Evidence suggests that GOM carbonate chemistry is mainly influenced by physical mixing, changes in atmospheric CO2 levels, and localized processes including eutrophication, hypoxia, and upwelling. The purpose of this dissertation is to increase sampling coverage in the northwestern Gulf (nwGOM), analyze decadal trends using both new and existing data, explore two cross-shelf transects from surface to bottom over 16+ years, and develop statistical models to estimate pH and ΩAragonite from hydrographic measurements. The research incorporates both laboratory and computational analyses across all chapters, including data collected from sensors (moored and shipboard). Samples for carbonate chemistry parameters were analyzed in the lab following standard practices. Computational work was conducted using RStudio, Python, and MATLAB. The statistical models can estimate water column pH and ΩAragonite with R2 values over 0.93 with small mean square errors (<0.0005 and <0.04 for pH and ΩAragonite, respectively), demonstrating their effectiveness. Key findings include seasonal patterns and long-term temperature trends in the nwGOM, as well as spatial variability and upward shoaling of the aragonite saturation horizons (ΩAragonite) from full water-column transects. These results reveal that subsurface waters are experiencing both declining dissolved oxygen (DO) and a shoaling saturation horizon. At the same time, surface waters also show progressive acidification, marked by decreasing pH and rising CO2 partial pressure (pCO2), despite significant seasonal fluctuations and an overall warming trend. The collected data provide essential spatial and temporal coverage of carbonate chemistry. The numerous changes occurring in the Gulf highlight the importance of quantifying these variations to guide resource management and conservation efforts.
Continue reading ‘Ocean acidification in the Northwestern gulf of America’Functional saturation of Earth’s habitable domains: constraints on land systems and potential in marine environments
Published 16 October 2026 Science ClosedTags: algae, Antarctic, North Atlantic, phanerogams, review, socio-economy
In this context, functional saturation is defined as the state in which a system’s capacity to sustain additional productive or regulatory functions becomes constrained due to cumulative anthropogenic pressures, even if some physical space remains available. This review examines whether the progressive contraction of terrestrial plant communities under intensifying anthropogenic pressure can be functionally compensated by the expansion of marine macroalgal systems in a high-CO2 world. Integrating perspectives from Earth system ecology, biogeochemistry, and spatial analysis, the study evaluates three interdependent dimensions: the saturation of habitable terrestrial space, the relative openness yet ecological constraint of marine environments, and the dynamic coupling between atmospheric CO2 and ocean chemistry. The synthesis reveals a fundamental asymmetry between land and ocean systems. Terrestrial ecosystems are undergoing direct structural transformation through land-use change, resulting in a measurable contraction of ecologically functional space and increasing transgression of planetary boundaries. In contrast, marine systems retain substantial geometric space but are subject to diffuse, cumulative stressors, particularly in productive coastal zones where macroalgal communities are most viable. Elevated CO2 exerts dual effects on marine primary producers, simultaneously enhancing photosynthetic potential while intensifying ocean acidification, with temporally lagged responses mediated by air–sea exchange dynamics. Although macroalgae may exhibit localized increases in productivity, their capacity to provide long-term carbon sequestration and ecosystem stability remains inherently limited due to rapid biomass turnover, susceptibility to regime shifts, and the interaction of multiple stressors. The available evidence suggests that marine macroalgal expansion is unlikely to fully compensate for terrestrial vegetation loss at global ecological and biogeochemical scales. Instead, the Earth system is undergoing a net reduction in biospheric resilience, characterized by declining terrestrial complexity and increasingly unstable marine productivity. These findings challenge assumptions of compensatory redistribution of primary production and underscore the necessity of preserving terrestrial ecosystems alongside mitigating pressures on marine environments.
Continue reading ‘Functional saturation of Earth’s habitable domains: constraints on land systems and potential in marine environments’Reducing nitrate loads to the St. Lawrence river could mitigate hypoxia and acidification in its deep estuary and gulf
Published 15 October 2026 Science ClosedTags: biogeochemistry, chemistry, field, modeling, North Atlantic, regionalmodeling
Hypoxia in marine systems is expanding worldwide due to anthropogenic activities. Deep waters of the St. Lawrence Estuary and Gulf are rapidly deoxygenating (∼1 mmol O2 m−3 y−1), driven by changes in Atlantic water-mass intrusion and nutrient‐fueled remineralization, and are simultaneously acidifying (∼0.004 pH unit y−1). These changes alter biogeochemical cycles and degrade habitats, causing biotic and economic consequences. Using a coupled physical-biogeochemical model, we tested whether watershed-scale nitrate reductions could mitigate deep‐water deoxygenation and carbonate-system degradation. Three nitrate‐reduction scenarios reduced riverine St. Lawrence River nitrate loads by about 11%, 30%, and 50% (−2.8, −7.5, and −11.7 mmol N m−3, respectively). Relative to the baseline simulation, these scenarios increased dissolved oxygen concentrations (DO) (+1.6, +4.3, and +6.7 mmol O2 m−3), pH (+0.004, +0.010, and +0.016), and aragonite saturation state (Ωarag) (+0.003, +0.009, and +0.015) in the deep Laurentian Channel (⩾175 m). The volume of deep waters with DO saturation <30% decreased by 3%, 8%, and 13% (−27, −75, −122 km3), while volumes with pH <7.65 declined by 1.0%, 2.8%, and 4.5% (−22, −60, −96 km3). Severely corrosive waters (Ωarag <0.6) dropped by 1.4%, 3.7%, and 5.9% (−26, −71, −112 km3). Over 2014–2024, modelled improvements exceeded small interannual variability but remained within seasonal amplitudes of deep DO concentrations (∼11 mmol O2 m−3) and pH (∼0.015 units), nevertheless pointing to a detectable management signal. Although nutrient‐driven improvements remained smaller than climate‐forced trends, modelled nitrate load reductions could offset ∼56% and 80% of recent observed oxygen and pH declines, respectively, while reducing hypoxic and acidified (pH and Ωarag) water volumes. These findings provide quantitative evidence that watershed‐scale nitrogen mitigation, through improved agricultural practices and wastewater nitrogen removal, which necessitates cooperation across jurisdictions, can alleviate hypoxia and acidification in deep coastal ecosystems, making nutrient management an essential complement to climate adaptation strategies.
Continue reading ‘Reducing nitrate loads to the St. Lawrence river could mitigate hypoxia and acidification in its deep estuary and gulf’Spatiotemporal water quality dynamics in Southern U.S. coastal reserves: a long-term perspective
Published 14 October 2026 Science ClosedTags: chemistry, modeling, North Atlantic, regionalmodeling
Water quality monitoring in estuarine ecosystems is essential for assessing the health and sustainability of these dynamic coastal habitats, which are increasingly vulnerable to environmental change and human impacts. This study aims to characterize long-term trends and seasonal drivers of seven key water quality parameters: temperature, salinity, dissolved oxygen (DO), pH, chlorophyll-a (Chla), nitrate + nitrite (NOx), and phosphate (PO4) across four southern U.S. National Estuarine Research Reserves (Apalachicola Bay, Grand Bay, Mission-Aransas, and Weeks Bay) to identify which reserves and processes are most vulnerable to climate and anthropogenic change. Using two decades of data (1995–2020) and applying Generalized Additive Models (GAMs), we identified significant spatial and temporal patterns linked to environmental and anthropogenic factors. Results revealed a warming trend in Weeks Bay (+0.1035 °C/year, P = 0.0013), a salinity decline in Grand Bay (−0.1699 PSU/year, P = 0.033), and a salinity increase in Apalachicola Bay (+0.2055 PSU/year, P = 0.003). DO concentrations peaked in spring and dropped in summer, reflecting seasonal nutrient inputs. Grand Bay exhibited the highest Chla variability (CV=131.48%). NOx concentrations declined in Grand Bay (−0.0003 mg/L/year, P = 0.0162), while PO4 levels remained relatively stable. pH trends suggested localized acidification, particularly in Mission-Aransas (−0.0071/year, P = 0.0016). GAM results emphasized the combined effects of long-term and seasonal changes, with site-specific differences. These findings provide critical insights into estuarine functioning and highlight the need for regionally tailored management strategies to enhance resilience and biodiversity conservation in U.S. coastal reserves.
Continue reading ‘Spatiotemporal water quality dynamics in Southern U.S. coastal reserves: a long-term perspective’Carbon dynamics and water quality regulation in Ruditapes philippinarum-Chlorella vulgaris co-culture with cardiac monitoring
Published 8 October 2026 Science ClosedTags: algae, biological response, BRcommunity, chemistry, fisheries, mitigation, mollusks, North Atlantic, physiology
Highlights
- Clam addition rapidly altered nitrogen, oxygen and dissolved-carbon dynamics.
- All chamber treatments maintained negative CO₂ fluxes during incubation.
- Algal monoculture showed stronger 6-h CO₂ uptake than co-culture.
- Hydrochemical variables and cardiac activity were recorded concurrently.
Abstract
Global warming and ocean acidification threaten marine aquaculture. Bivalve-microalgae co-culture is considered a promising approach for low-carbon aquaculture, but its effects on water quality, carbon dynamics and bivalve physiology are not fully understood. This study tested Ruditapes philippinarum and Chlorella vulgaris in sealed static chambers with three treatments: sterile seawater (NP-C), Chlorella monoculture (WP-C) and clam-Chlorella co-culture (WP). Water-quality variables, dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), air-water CO₂ flux and clam heart rate were measured in separate 3-h and 6-h incubations. At the end of incubation, WP had higher ammonium concentrations and lower dissolved oxygen than WP-C, indicating that clam addition changed nitrogen and oxygen conditions. DOC and DIC also changed differently in the two biological treatments. All treatments showed negative air-water CO₂ fluxes. In the 6-h experiment, CO₂ uptake was strongest in WP-C and intermediate in WP. Heartbeats were recorded continuously in four clams for 7.07 h. Overall, the co-culture rapidly altered water-quality and dissolved-carbon dynamics but did not result in greater short-term CO₂ uptake than the algal monoculture under the present chamber conditions.
Continue reading ‘Carbon dynamics and water quality regulation in Ruditapes philippinarum-Chlorella vulgaris co-culture with cardiac monitoring’Projecting the impact of climate change on the lipid profile of the hydrocoral Millepora alcicornis: relative lipid homeostasis under warming and ocean acidification
Published 25 September 2026 Science ClosedTags: biological response, corals, laboratory, multiple factors, North Atlantic, physiology, temperature
Climate change exerts a strong impact on marine ecosystems, particularly through ocean acidification and rising water temperatures. Within this context, shifts in lipid composition have emerged as valuable stress indicators in many organisms, providing insights into the trophic ecology of ecosystems. The objective of this study was to assess the combined effects of warming and ocean acidification scenarios projected for the end of the century (+5 °C and pH 7.5) on the lipid profiles of the hydrocoral Millepora alcicornis, recently recorded for the first time in Tenerife (Canary Islands, Spain). After an 84-day experiment, corals exhibited significant reductions in total lipid content, key lipid classes and fatty acids, particularly triacylglycerides (TAG) and docosahexaenoic acid (DHA, 22:6n-3), whereas sterol esters (ST) and saturated fatty acids (SFAs) showed the opposite trend. By contrast, symbiont-derived glycolipids and C18 fatty acids characteristic of zooxanthellae were not significantly affected by environmental stress, suggesting relative stability of membrane lipid composition. Overall, the maintenance of membrane lipid composition in symbiotic algae together with evidence of lipid remodelling in the host suggests a capacity for short-term physiological acclimation of M. alcicornis under the simulated climate change conditions. However, reduced DHA availability may have important physiological implications for the colonies, justifying future studies on the molecular regulation of LC-PUFA biosynthesis and the long-term acclimation capacity of Millepora alcicornis under climate change.
Continue reading ‘Projecting the impact of climate change on the lipid profile of the hydrocoral Millepora alcicornis: relative lipid homeostasis under warming and ocean acidification’Ocean acidification drives grazer niche convergence and trophic homogenization in benthic communities
Published 22 September 2026 Science ClosedTags: algae, annelids, biological response, BRcommunity, community composition, crustaceans, echinoderms, field, North Atlantic, otherprocess, performance, porifera, vents
Highlights
- Acidification compresses benthic community isotopic space via carbon homogenization.
- Functional groups show differential isotopic responses consistent with bottom-up trophic reorganization.
- Arbacia lixula shifts from a sponge-dominated diet to herbivory under low pH.
- Paracentrotus lividus maintains stable trophic niche despite acidification.
- Asymmetric grazer responses drive site-specific increases in isotopic niche overlap under acidification.
Abstract
Ocean acidification is expected to alter marine food webs, yet community-level evidence from long-term, naturally acidified systems remains limited. We used stable isotope ratios (δ13C and δ15N) to investigate how natural acidification restructures benthic trophic interactions, from basal resources to consumer niche dynamics, a naturally acidified system (pH gradient: 8.1 to ~7.4; pHT scale) spanning present-day to end-of-century projected conditions (SSP2–4.5 to SSP5–8.5). After accounting for local differences in the isotopic baseline, we found that: (1) community isotopic space contracted under acidification, with the carbon range decreasing as primary producers converged toward 13C-depleted values, while the nitrogen range expanded, indicating species-specific trophic adjustments; (2) functional groups responded asymmetrically, with primary producers showing the strongest δ13C shifts, filter-feeders remaining relatively stable, and omnivorous consumers showing reduced δ13C and δ15N values; (3) the two dominant sea urchin grazers responded in opposite directions — the macrophyte-based omnivore Paracentrotus lividus maintained stable isotopic values across the pH gradient, whereas the invertebrate-based omnivore Arbacia lixula exhibited pronounced isotopic shifts — resulting in markedly increased, though site-dependent, niche overlap at the most acidified sites (up to 27%); (4) Bayesian mixing models revealed that this convergence was driven by dietary shifts in A. lixula, which transitioned from a predominantly invertebrate-based diet (70–79% animal prey) toward algal-based feeding under acidification (19–24% animal prey), while P. lividus maintained relatively consistent dietary composition (50–70% algae). Together, these results indicate that acidification-driven homogenization of primary producers, combined with asymmetric consumer responses, compresses trophic niche space, with broad implications for the resilience and functioning of benthic ecosystems under future ocean change.
Graphical abstract
Along a natural CO2 gradient in the Canary Islands (pH 8.1–7.4, pHT scale; spanning present-day to end-of-century projected conditions, SSP2-4.5–SSP5-8.5), ocean acidification compresses community isotopic space through homogenization of primary producers. The two dominant sea urchin grazers respond asymmetrically: Paracentrotus lividus maintains a stable trophic niche, while Arbacia lixula shifts toward algal-based feeding, increasing niche overlap up to 27% at the most acidified sites.
Evaluating the combined effects of harmful algal blooms and low pH exposure on the development and hatching success of Artemia salina
Published 21 September 2026 Science ClosedTags: biological response, communityMF, crustaceans, laboratory, morphology, multiple factors, North Atlantic, reproduction, toxicants, zooplankton
Highlights
- Hatching success of Artemia salina was impaired by acidified conditions.
- Development of Artemia salina pre-nauplii was negatively impacted by both species of harmful algae and low pH exposure.
- Only toxin-producing harmful algal species produced significant morphological abnormalities of pre-naupliar Artemia salina.
- No synergistic effects of harmful algae and low pH exposure was seen in this study.
Abstract
Harmful algal blooms (HABs) and ocean acidification are major stressors in coastal marine ecosystems, yet their combined effects on early zooplankton development remain poorly understood. This study tested whether HABs and low pH exposure exert synergistic effects on the embryonic development and hatching success of brine shrimp (Artemia salina) cysts. Cysts were exposed to controls, toxin-producing HAB species (i.e. Margalefidinium polykrikoides or Alexandrium catenella), or a non-toxin producing HAB control (i.e. Gymnodinium aureolum) and at either ambient (pH ∼ 8) or acidified (pH ∼ 7.2) conditions. We hypothesized that the combined exposure to a toxin-producing HAB at acidified pH conditions would reduce hatching success and alter embryonic morphology. Low pH exposure consistently reduced hatching success and slowed developmental progression across treatments, reducing nauplii production. HAB exposure alone did not affect hatching success, but exposure to toxin-producing HABs in ambient pH conditions did significantly increase the morphological abnormalities at the membrane stage. Overall, no synergistic effects of HABs and low pH exposure were found for any response variable. Instead, HABs and low pH exposure exerted distinct, stage-specific impacts that were additive rather than interactive. These findings suggest that while exposure to toxin-producing HABs primarily disrupts morphology and low pH exposure slows development and reduces hatching success, their combined effects do not exceed additive expectations. Future work should explore physiological mechanisms underlying these stress responses and assess whether similar patterns occur in other cyst-producing zooplankton.
Coral acclimatization to novel, co-varying stressors is associated with fitness trade-offs
Published 18 September 2026 Science ClosedTags: adaptation, biological response, calcification, corals, field, morphology, mortality, multiple factors, North Atlantic, oxygen, photosynthesis, physiology, respiration, temperature
Reef-building corals are under pressure to acclimatize and/or adapt to multiple co-occurring stressors, including climate change and declines in water quality. However, their capacity to do so is largely unknown. Yet, some corals naturally persist in habitats with multi-stressor conditions which can provide crucial insight into coral adaptive capacity under future ocean conditions. To assess the role of phenotypic plasticity and local adaptation in coral acclimatory responses to novel conditions, we reciprocally transplanted two coral species (Siderastrea siderea, branching Porites) between an inland bay characterized by multiple, co-varying stressors, including warmer seawater temperatures, higher pollution and more variable temperatures, pH and dissolved oxygen concentrations, and an environmentally less extreme, more stable fringing reef. We measured key phenotypic traits (e.g., calcification, tissue biomass, metabolic rates, chlorophyll concentrations) of all transplant groups after 0, 4 and 12 months. Reef-origin corals demonstrated high plasticity when transplanted to the bay, as both species maintained high survival and calcification, and matched bay natives’ other phenotypic traits. Yet, reef-to-bay transplants of both species had reduced photosynthesis-to-respiration ratios in the bay, highlighting the risk of metabolic trade-offs unless compensated for through increased heterotrophy. Conversely, bay-origin corals had enhanced photosynthetic performance but lower calcification on the reef. Reaction norms provided stronger evidence for environmental specialization in bay-origin than reef-origin corals, which could limit their use as stress-tolerant source corals for reef restoration. Overall, our findings suggest multi-stressor variability may promote specialized genotypes, rather than increased phenotypic plasticity, though this may also depend on predictability of environmental variability.
Continue reading ‘Coral acclimatization to novel, co-varying stressors is associated with fitness trade-offs’Coastal marine carbon and air-sea fluxes quantified from pH sensors on an extended AUV deployment
Published 16 September 2026 Science ClosedTags: chemistry, field, methods, North Atlantic
For the first time, the Autosub Long Range (ALR) completed a fully autonomous, long-distance (2,000 km) scientific mission, delivering new insight into coastal carbonate dynamics and air-sea CO2 fluxes. Equipped with a suite of oceanographic sensors, including a Lab-on-Chip (LOC) pH sensor and a Sea-Bird SeaFET pH sensor, the mission generated nearly 50,000 high-resolution pH measurements, providing one of the most detailed continuous coastal carbonate data sets collected to date in the region. We evaluated the adjustment of the SeaFET reference potential (k0), testing both the co-deployed LOC sensor and neural network estimates as reference pH. Before correction, the LOC and SeaFET sensors showed close agreement (ΔpHT = 0.013 ± 0.009), which improved to ΔpHT = 0.00004 ± 0.007 after LOC-based k0 adjustment. Both sensors diverged from model estimates, indicating reduced ability of models to resolve fine-scale coastal variability and reinforcing the need for direct in situ observations. Total alkalinity (TA) was derived from salinity-based relationships and model predictions, and paired with pH (SeaFET, LOC, and modeled) to estimate the partial pressure of CO2 (pCO2), which ranged 263–598 ± 27 μatm. Resulting air-sea CO2 fluxes ranged −17.0 to 7.1 ± 1.09 mmol m−2 d−1, with the Celtic Margin acting as a net CO2 sink in May–June of 2022. pCO2 and CO2 flux proved sensitive to subtle pH differences, but less so to TA estimates. Our findings demonstrate the critical role of high-resolution autonomous observations in quantifying coastal carbonate dynamics and CO2 fluxes, capturing processes and variability that are largely unresolved by ship-based surveys or global models.
Plain Language Summary
For the first time, the Autosub Long Range (ALR), a robotic underwater vehicle, completed a long-distance (2,000 km) scientific mission without ship support. During the mission, the ALR collected ocean data using sensors that measured water temperature, oxygen, and seawater acidity (pH). The mission generated nearly 50,000 high-resolution pH measurements, providing one of the most detailed continuous coastal carbonate data sets collected in this region. We evaluated how well two onboard pH sensors agreed with each other and with model-based estimates, and tested an applied correction method. Before and after correction, the sensors closely agreed, showing that autonomous platforms can gather high-quality chemical measurements that resolve coastal marine carbon dynamics better than model estimates alone. We used the pH data, along with estimates of TA, to calculate carbon dioxide (CO2) exchange between the ocean and atmosphere, finding that the region operates primarily as a carbon sink in May–June. Our calculations were strongly influenced by pH input but much less by alkalinity, highlighting the importance of accurate pH observations. This study shows that autonomous sensors can improve monitoring of carbon cycling in dynamic, understudied coastal waters that play a key role in the global carbon system.
Continue reading ‘Coastal marine carbon and air-sea fluxes quantified from pH sensors on an extended AUV deployment’Combined effect of ocean warming and acidification on the sea pen “Pennatula phosphorea”
Published 10 September 2026 Science ClosedTags: biological response, BRcommunity, cnidaria, laboratory, mortality, North Atlantic
Anthropogenic CO2 emissions are expected to increase ocean acidity and temperature over the coming century. Under the Shared Socioeconomic Pathway (SSP) 5–8.5 scenario, mean surface ocean pH is projected to decrease by approximately 0.39 units, while sea surface temperature is expected to rise by 2–4 °C between 2010 and 2100. Sea pens (Octocorallia) are important bioindicators of soft-sediment habitat quality and associated benthic communities; however, their responses to these stressors remain considerably less studied than those of their hexacoral counterparts.
This thesis investigates the individual and combined effects of ocean acidification and warming, based on SSP5–8.5 projections, on the sea pen Pennatula phosphorea (Linnaeus, 1758), collected from the Swedish Gullmarsfjord. During winter and summer 2025, four pH treatments (8.0, control; 7.8, present-day low value; 7.4, projected low value for 2100; and 7.0, extreme scenario) and four temperature treatments (7.7 °C, winter control; 14 °C, summer control; 17 °C, present-day high value; and 20 °C, projected high value for 2100) were assessed. Response variables included behavioural traits (colony burrowing, colony inflation, polyp opening and bioluminescence emission), survival, and bioluminescence substrate levels (coelenterazine concentration and maximum light intensity, Lmax). Three hypotheses were tested: (1) ocean acidification and warming would negatively affect all response variables, with stronger effects under combined exposure; (2) prolonged exposure would result in either progressive deterioration or acclimation of behavioural traits; and (3) larger individuals would be less affected by stressors than smaller individuals.
The effects of acidification and warming varied among response variables, seasons, and whether stressors were applied individually or in combination. Overall, pH 7.8 produced few significant effects, except on burrowing behaviour, whereas pH 7.4 and 7.0 generated effects ranging from negligible (p > 0.1) to highly significant (p < 0.01), generally with greater impacts at pH 7.0. Similarly, temperatures of 17 and 20 °C elicited responses ranging from negligible to highly significant, with the strongest effects observed at 20 °C for quantitative measures of bioluminescence substrates. Combined exposure generally amplified the observed effects, suggesting that tolerance to one stressor may be compromised by the presence of another. No consistent evidence of behavioural acclimation or progressive deterioration was detected over time. Contrary to the initial hypothesis, larger individuals appeared more susceptible to environmental stressors than smaller individuals.
Continue reading ‘Combined effect of ocean warming and acidification on the sea pen “Pennatula phosphorea”’Elevated pCO2 impairs overall byssus attachment strength in the blue mussel (Mytilus edulis) without altering byssus thread quality
Published 8 September 2026 Science ClosedTags: biological response, BRcommunity, laboratory, mollusks, North Atlantic, physiology
Increasing atmospheric carbon dioxide (CO2) is driving global ocean acidification (OA). This process may threaten the persistence of bed-forming mussels by weakening the byssal system that anchors them to the seafloor. Here, blue mussels (Mytilus edulis) were exposed to present-day (∼460 ppm pCO2) normocapnic and projected end-century (∼1200 ppm pCO2) hypercapnic conditions for four weeks at 12 °C. Byssus production, thread morphology, whole-byssus mechanics and the underlying physiological condition index (CI) were quantified. Unlike previous studies, this study analysed the byssus as an intact functional unit. This approach better reflects its mechanical performance in situ. Median thread production fell by 50% under elevated pCO2 and the number of individuals producing no threads at all increased from 3% to 23% of the population. Thread diameter and plaque area were unaffected. Whole byssus tensile testing revealed a distinctive mechanical pattern (elastic loading, force plateau, and structural failure) regardless of environmental CO2 concentration. Whole byssus attachment strength scaled linearly with thread number in both treatments, and the mechanical work required to detach mussels under hypercapnia dropped by 42%. Elevated pCO2 reduced mussel condition index by 19% relative to the control, indicating an energetic burden. These results show that near-future ocean acidification weakens mussel attachment primarily by lowering individual physiological condition, which directly drives the reduction in total attachment energy, rather than by lowering individual thread quality. This likely results from a shift in energy use away from thread production, as seen in poorer mussel condition. As a result, mussels may become more prone to being dislodged by waves or predators. The findings of this study indicate that ocean acidification can reduce the overall strength of M. edulis beds, with important effects on rocky shore ecosystems and the viability of mussel farming in a changing climate.
Continue reading ‘Elevated pCO2 impairs overall byssus attachment strength in the blue mussel (Mytilus edulis) without altering byssus thread quality’High-resolution mapping of carbonate system parameters over coastal waters using integrated uncrewed aircraft systems (UAS) and Autonomous Surface Vessel (ASV) observations
Published 7 September 2026 Science ClosedTags: chemistry, field, modeling, North Atlantic, regionalmodeling
Coastal acidification, distinct from ocean acidification, is influenced by localized factors such as nutrient runoff, freshwater input, and decomposition. This study estimates carbonate system parameters in the Western Mississippi Sound (WMS) using integrated uncrewed aircraft systems (UAS) and autonomous surface vessel (ASV) observations. During 2018 to 2022, high-ressolution UAS imagery and in 2021 in situ ASV data including pH, pCO2, SST, SSS, CDOM, and Chl-a were collected. Machine learning algorithms were developed to estimate pCO2 and total alkalinity (TA), with random forest models achieving high accuracy (R2 > 0.91). A CDOM-based model was developed to derive SSS, which, along with Chl-a, fed into time-series mapping of TA and pCO2. Results highlight the effectiveness of combining UAS and ASV data to produce fine-scale carbonate system maps. This approach supports improved monitoring of coastal acidification and can be extended to estimate additional parameters such as calcite and aragonite saturation states and DIC.
Continue reading ‘High-resolution mapping of carbonate system parameters over coastal waters using integrated uncrewed aircraft systems (UAS) and Autonomous Surface Vessel (ASV) observations’
