multiple factors Archives - Page 3 of 128

Posts Tagged 'multiple factors'

Metabolic rate measurements of two benthic invertebrates under simulated climate change conditions

Published 16 February 2026 Science Closed
Tags: 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.

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Acute microbial and nutrient responses to elevated temperature and pCO2: a coastal UK microcosm study

Published 13 February 2026 Science Closed
Tags: 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.

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Experimental exposure to climate change scenarios imposed alterations on the morphological traits of sessile and low-motility marine invertebrates

Published 6 February 2026 Science Closed
Tags: 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’

Photoaged microplastics disrupt the response of marine medaka (Oryzias melastigma) to ocean acidification: perspectives from energy metabolism and ammonia production

Published 2 February 2026 Science Closed
Tags: biological response, fish, laboratory, molecular biology, multiple factors, North Pacific, physiology, plastics, respiration

Ocean acidification (OA) and microplastics (MPs, <5 mm) are co-occurring stressors that threaten marine ecosystems. Although the marine environment contains multiple pollutants, OA can alter the environmental behavior of MPs, influencing their toxicity and environmental fate. Therefore, investigating the interactive effects of OA and MPs is essential. Fish can activate physiological compensatory mechanisms to adapt to OA; however, it remains unclear how MPs affect these mechanisms. In this study, marine medaka were exposed to acidified seawater (pH 7.70) containing environmentally relevant concentrations of MPs (0.1 mg/L) for 90 days to investigate the disruptive effects of MPs on responses to OA. The results showed that while OA triggered compensatory energy metabolism reprogramming to enhance ammonia production, MPs disrupted this process, reducing the TCA cycle intermediate α-ketoglutarate. This α-ketoglutarate deficiency limited the glutamate supply for ammonia production. Simultaneous inhibition of glutamate dehydrogenase activity further limited glutamate availability. As a result, MPs reduced the level of ammonia production by 25.29%, compromising the ability to neutralize excess H⁺. Crucially, photoaging exacerbated this toxicity, leading to a 32.04% reduction in ammonia production. This study demonstrates that MPs interfere with fish responses to OA via α-ketoglutarate-mediated metabolic reprogramming, highlighting a vulnerability in marine organisms facing climate change scenarios.

Continue reading ‘Photoaged microplastics disrupt the response of marine medaka (Oryzias melastigma) to ocean acidification: perspectives from energy metabolism and ammonia production’

Triple threat: ocean acidification, warming, and hyposalinity synergistically weaken shell integrity in a Mediterranean calcifying mollusk

Published 30 January 2026 Science Closed
Tags: 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 Closed
Tags: 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.

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An experimental approach to study climate change stress in benthic marine invertebrates

Published 26 January 2026 Science Closed
Tags: 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.

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Transcriptomic responses of the marine diatom Phaeodactylum tricornutum to high carbon and low nitrogen stress

Published 23 January 2026 Science Closed
Tags: adaptation, biological response, laboratory, molecular biology, multiple factors, nutrients, otherprocess, phytoplankton

Diatoms play a pivotal role in global biogeochemical cycling and marine primary productivity, making them ideal model organisms for understanding how phytoplankton respond to environmental fluctuations associated with global climate change. In natural marine systems, diatoms frequently encounter simultaneous variations in carbon and nitrogen availability, yet most previous studies have examined the effects of these factors in isolation. To elucidate the integrated transcriptional mechanisms underlying diatom acclimation to coupled carbon–nitrogen (C—N) imbalance, we employed RNA sequencing (RNA‐Seq) to characterize the global transcriptional response of the model diatom Phaeodactylum tricornutum to high CO₂ (~2000 μatm) and low nitrogen (10% of nitrogen concentration in f/2 medium) under parallel culture conditions. The results revealed both shared and distinct transcriptional responses between the two treatments. Key genes involved in carbon metabolism, such as phosphoglycerate mutase (PGAM_7) and dihydrolipoamide succinyltransferase (PHATRDRAFT_40430), were significantly upregulated, indicating enhanced glycolytic and TCA cycle activity. In contrast, the Calvin‐cycle enzyme fructose‐1,6‐bisphosphatase (FBPC4) was downregulated. Genes associated with nitrogen assimilation‐including nitrate reductase (PHATRDRAFT_54983), nitrite reductases (PHATRDRAFT_13154, PHATRDRAFT_8155), and ferredoxin–nitrite reductase (PHATRDRAFT_27757)‐were strongly induced under both conditions. Pathway enrichment analysis further indicated the activation of lactic acid fermentation and nitrogen salvage pathways, suggesting a metabolic shift toward energy conservation and nutrient recycling. Collectively, these findings provide an overview of the transcriptional adjustments that enable P. tricornutum to maintain C—N homeostasis under high CO₂ and low nitrogen stress, offering new insights into diatom metabolic plasticity under changing ocean conditions.

Continue reading ‘Transcriptomic responses of the marine diatom Phaeodactylum tricornutum to high carbon and low nitrogen stress’

Northern shrimp exhibit origin-specific proteomic remodelling under ocean acidification, with limited response to ocean warming

Published 19 January 2026 Science Closed
Tags: 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 Closed
Tags: 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.

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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 Closed
Tags: 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 Closed
Tags: 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.

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Physiological and transcriptomic responses of a harmful algal bloom-causing dinoflagellate Karenia mikimotoi to multiple environmental factors

Published 12 January 2026 Science Closed
Tags: 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’

From pollution to ocean warming: the climate impacts of marine microplastics

Published 9 January 2026 Science Closed
Tags: multiple factors, plastics, review

Highlights

MPs disrupt nutrient cycling and influence climate-related processes.
MPs interact with ocean warming and acidification, amplifying ecological impacts.
Combined effects of MPs, warming, and acidification threaten marine ecosystem stability.
MP pollution hinders progress toward multiple UN SDG targets.

Abstract

Despite being a critical global issue, the role of microplastics (MPs) in climate change has received limited attention. Climate disruption and plastic pollution are two major environmental challenges that intersect in complex ways. MPs influence biogeochemical processes, disrupt oceanic carbon pumps, and contribute directly to greenhouse gas (GHG) emissions. In marine ecosystems, MPs alter the natural carbon sequestration by affecting phytoplankton and zooplankton, which are key agents of carbon cycling. Additionally, the plastisphere, a microbial community colonizing MPs, plays a significant role in GHG production due to its diverse microbial networks. This review highlights the close relationship between MP pollution and climate change, suggesting that MPs may significantly contribute to climate change and potentially further affect ocean health in the form of ocean warming and ocean acidification. Given the interconnected nature of these challenges, a holistic and integrated strategy is essential to effectively address them. Furthermore, this article examines MP pollution through the lens of the UN Sustainable Development Goals (SDGs) and human rights, recognizing that MP pollution can hinder the implementation of sustainable strategies and action plans necessary for achieving the SDGs.

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Strength and duration of diel pH and dissolved oxygen cycles control the survival and performance of early life stage North Atlantic bivalves (Mercenaria mercenaria, Crassostrea virginica, Argopecten irradians and Mytilus edulis)

Published 9 January 2026 Science Closed
Tags: biological response, growth, laboratory, mollusks, mortality, multiple factors, North Atlantic, oxygen, physiology, reproduction, respiration

Highlights

Cycling from nocturnal hypoxia – acidification to mild hyperoxia- hypocapnia reduced larval survival in all experiments.
Cycling from nocturnal hypoxia – acidification to normoxia- normocapnia reduced survival of larvae in 50 % of experiments.
Nocturnal hypoxia and acidification caused increased clearance and respiration rates in juvenile mussels.
The impacts of diel DO and pH cycles on early life stage bivalves depend on cycle duration, cycle intensity, and species.

Abstract

Many economically important bivalves spawn during the summer months when diel cycles of dissolved oxygen (DO) and pH occur in estuaries. Little is known, however, regarding how cycles of differing durations and magnitudes affect these organisms. Here, larval bivalves (Mercenaria mercenaria, Crassostrea virginica, Argopecten irradians) and juvenile mussels (Mytilus edulis) were exposed to cycles of low DO and pH of varying duration (4-, 6-, 8-, and 12-h) and strength (moderate: DO range ∼ 6 mg L⁻¹, pH range ∼ 0.6 and severe: DO range ∼ 10 mg L⁻¹, pH range ∼ 0.9) compared to positive (normoxic and normocapnic) and negative (hypoxic and acidified) static controls. Growth, survival, respiration and clearance rates were measured. During experiments, 12 h of nocturnal hypoxia and acidification coupled with mildly hyperoxic (∼11.3 mg L⁻¹ DO) and hypocapnic (∼8.13 pH) conditions by day significantly reduced survival in larval C. virginica, M. mercenaria, and A. irradians in all experiments (p < 0.05), while 12 h of nocturnal hypoxia and acidification without hyperoxic and hypocapnic conditions did so in only half of experiments indicating that hyperoxia and hypocapnia were additional and significant stressors. Six hours of low DO/pH significantly reduced survival in only 16 % of experiments, indicating that larval bivalves are more impacted by longer duration and greater magnitude cycles of DO and pH compared to cycles of shorter duration or lower magnitude. Across species, M. mercenaria larvae were more resilient to nocturnal hypoxia and acidification than A. irradians and C. virginica. The growth and survival of juvenile M. edulis were unaffected by nocturnal hypoxia and acidification but mussels experienced significantly increased clearance and respiration rates under these conditions (p < 0.01) evidencing physiological mechanisms for coping with these stressors. Collectively, this study demonstrates that the impacts of diel DO and pH cycles on early life stage bivalves are dependent upon cycle duration, cycle intensity, bivalve life stage, and bivalve species.

Continue reading ‘Strength and duration of diel pH and dissolved oxygen cycles control the survival and performance of early life stage North Atlantic bivalves (Mercenaria mercenaria, Crassostrea virginica, Argopecten irradians and Mytilus edulis)’

Combined effects of ocean acidification, warming, and salinity on the fertilization success in an Arctic population of sea urchins

Published 9 January 2026 Science Closed
Tags: 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.

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Effect of experimental seawater acidification on the prooxidant-antioxidant system of the Pacific oyster Magallana gigas (Thunberg, 1793) under normoxic and hypoxic conditions

Published 8 January 2026 Science Closed
Tags: biological response, Black Sea, fisheries, laboratory, mollusks, mortality, multiple factors, oxygen, physiology

Highlights

Lipid peroxidation in oyster gills was enhanced during exposure to acidification + hypoxia.
SOD and GPx activities changed in gills and hepatopancreas, while CAT activity unchanged in both.
Water acidification does not promote DNA strand breaks in hemocytes of M. gigas.
Acidification + hypoxia more severe damaging than acidification under normoxia.

Abstract

Bivalve mollusks, particularly the Pacific oyster (Magallana gigas), are both environmentally and commercially significant species that live in coastal waters and may be affected by global climate change factors including hypoxia and acidification. In this study, we investigated the impact of acidification in combination with normoxia and hypoxia on oxidative stress markers in the gills and hepatopancreas of M. gigas oysters. Oysters were collected from a shellfish farm and subjected to acidified conditions (pH 7.3 ± 0.05) in combination with either normoxic (8.0 ± 0.3 mg/L O₂) or hypoxic (2.0 ± 0.3 mg/L O₂) conditions for an 8-day period. Changes of DNA damage levels, reactive oxygen species (ROS) production in hemocytes, as well as antioxidant enzyme activities (catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx)) and lipid peroxidation in the gills and hepatopancreas were evaluated. Additionally, the mortality rate in experimental groups was monitored throughout the experiment. Our results showed that lipid peroxidation in gills was enhanced during prolonged acidification in combination with hypoxia (6–8 days). We observed rapid and consistent changes in SOD and GPx activity in gills and hepatopancreas. CAT activity remained stable in both tissues. The results of the study indicate that acidification was shown to induce oxidative stress in oysters. Combination of acidic environment to hypoxia had a more severe effect on oysters compared to acidification under normal oxygen conditions, leading to their death after 8 days of exposure.

Continue reading ‘Effect of experimental seawater acidification on the prooxidant-antioxidant system of the Pacific oyster Magallana gigas (Thunberg, 1793) under normoxic and hypoxic conditions’

Modeling the spatiotemporal effects of ocean acidification and warming on Atlantic sea scallop growth to guide adaptive fisheries management

Published 7 January 2026 Science Closed
Tags: 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’

Ocean acidification enhances microplastic uptake and alters physiological responses in Manila clams

Published 6 January 2026 Science Closed
Tags: biological response, laboratory, mollusks, multiple factors, North Pacific, physiology, plastics, respiration

Highlights

Ocean acidification (OA) impairs particle selection, increasing microplastic ingestion.
Microplastic retention in clams is higher under acidified conditions.
Stress-related suppression of filtration and respiration is diminished under OA.
OA and microplastics interact, highlighting multi-stressor ecological risks.

Abstract

Microplastic (MP) pollution and ocean acidification (OA) are co-occurring stressors in coastal ecosystems, yet their combined effects on bivalves remain unclear. We investigated how OA influences MP ingestion, excretion, and physiological performance in the Manila clam Ruditapes philippinarum. Clams were exposed to two pH levels (8.1 and 7.6) for 10 days and three MP concentrations (0, 10, and 1000 items/L) during the final three days. MP accumulation in gills/labial palps and digestive tracts, MP content in excreted material, and filtration and respiration rates were measured. Acidified conditions impaired particle selection, leading to greater MP accumulation in the digestive tract, whereas MP excretion was unaffected. Filtration and respiration were maintained at higher levels under OA, suggesting suppressed stress responses. These results demonstrate that OA enhances MP retention and modulates physiological stress reactions, highlighting synergistic effects that may influence energy balance and ecosystem functioning under future ocean conditions.

Continue reading ‘Ocean acidification enhances microplastic uptake and alters physiological responses in Manila clams’

Reproduction of the viviparous marine isopod Cirolana harfordi held in seawater with raised temperature and lowered pH

Published 2 January 2026 Science Closed
Tags: 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’

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