Seagrasses provide valuable ecosystem functions, yet they are declining globally due to anthropogenic stressors. Understanding how global climate stressors like ocean acidification interact with local environmental conditions (e.g., increased nutrient pollution) to affect ecosystem dynamics can be used to inform management of these habitats. In San Francisco Bay, it is unknown how stressor interactions will affect herbivory by Ampithoe valida, an invasive amphipod that exhibits novel feeding behavior by directly consuming the tissue of Zostera marina (eelgrass), which has been linked to negative impacts on local meadows. The goal of this study was to determine how anthropogenic stressors and amphipod size influence A. valida herbivory on eelgrass in San Francisco Bay to evaluate the ecological implications for eelgrass habitats. To further understand this relationship, feeding assays first examined food preferences of A. valida of three sizes on eelgrass of two ages and epiphytic algae. Secondly, a mesocosm experiment exposed A. valida of medium and large sizes to levels of ocean acidification expected with accelerating climate change and eelgrass to levels of nutrient pollution possible from point sources along shorelines, to test if these combined stressors affect A. valida direct herbivory of eelgrass. Additionally, A. valida were collected in the field during peak eelgrass growing season in summer and early fall to determine their size distributions and provide context to the experiments. Results found that A. valida largely prefer epiphytic algae over eelgrass regardless of their size. When offered only eelgrass, medium to large individuals consumed the tissue, whereas small individuals exhibited near-zero consumption. Although small A. valida were most abundant in field collections, medium-sized individuals were also present in moderate numbers, suggesting amphipods of this size may be the primary contributors to direct eelgrass consumption in San Francisco Bay, with high-consuming large individuals less common. Mesocosm results indicated that increased nutrients reduced eelgrass aboveground morphology (leaf size) and biomass, while tissue nutrient content increased, suggesting that although nutrients were taken up, they were not used for growth. Finally, feeding assays revealed that the effects of reduced pH and nutrient additions on A. valida eelgrass herbivory varied with grazer size and experimental context. In the no-choice assay, medium-sized individuals increased consumption under reduced pH relative to ambient pH, while large individuals consumed more of the highest nutrient-enriched eelgrass tissue. In contrast, the choice assay showed higher eelgrass consumption under ambient pH relative to reduced pH, and no effect of nutrient additions. This suggests that under reduced pH A. valida may shift their feeding behavior depending on environmental context, potentially increasing consumption through compensatory feeding on lower-quality tissue when food options are limited or reducing consumption when alternative refugia and higher-quality resources are available. This also indicates that ocean acidification may primarily alter eelgrass grazing behavior among mid sized A. valida, while nutrient enrichment may increase grazing pressure from larger individuals, potentially exacerbating eelgrass vulnerability in San Francisco Bay given reduced plant performance under high-nutrient conditions.
Continue reading ‘Anthropogenic stressors and amphipod size influence herbivory on eelgrass in San Francisco Bay’Posts Tagged 'mesocosms'
Anthropogenic stressors and amphipod size influence herbivory on eelgrass in San Francisco Bay
Published 15 July 2026 Science Leave a CommentTags: biological response, crustaceans, laboratory, mesocosms, morphology, multiple factors, North Pacific, nutrients, phanerogams, zooplankton
Climate change and aquatic ecosystems: impacts on salinity, species survival, and ecological resilience
Published 29 June 2026 Science ClosedTags: biological response, fisheries, mesocosms, mortality, phytoplankton, reproduction, review, salinity
Highlights
- Unveils Climate-Driven Disease Mechanisms Across Aquatic Systems.
- Integrates Multistressor Impacts Including Pollution, Eutrophication, and Salinity Fluctuations.
- Explores Shifts in Species Distribution, Reproduction, and Food Web Dynamics.
- Highlights Adaptive Traits and Resilience Mechanisms in Aquatic Organisms.
- Provides Science-Based Recommendations for Climate-Responsive Management.
Abstract
Climate change is rapidly transforming aquatic ecosystems, posing complex environmental challenges with far-reaching ecological and socio-economic implications. Rising temperatures, sea-level rise, altered precipitation patterns, shifting hydrological regimes, and sea-ice loss are intensifying pressures on coastal, estuarine, freshwater, and polar systems. These stressors contribute to habitat degradation, increased frequency of hypoxic events, and altered species distributions. Crucially, while some dual stressors, such as warming and acidification, can paradoxically increase primary producer biomass, our findings reveal that this resultant biomass often accumulates as detritus rather than being efficiently transferred to higher trophic levels. This observation directly challenges the simplistic assumption that “more growth” is invariably beneficial, highlighting complex indirect effects on food web dynamics and ecosystem function. Ecological perturbations propagate through trophic networks, resulting in biodiversity loss, reduced ecosystem resilience, and declining fisheries productivity, thereby threatening food security and coastal livelihoods. Marine and freshwater organisms are increasingly exposed to multiple, interacting stressors, including warming, acidification, salinity fluctuations (requiring distinct osmoregulatory strategies, e.g., heterosmotic regulation in teleosts vs. isosmotic intracellular regulation in crustaceans), pollution, and overexploitation. These cumulative pressures can exacerbate disease outbreaks, modify host–pathogen dynamics, and facilitate the emergence and spread of aquatic pathogens, with consequences for ecosystem stability and human health. In aquaculture systems, climate-driven stress often acts synergistically with anthropogenic disturbances, amplifying production risks and economic vulnerability. Furthermore, anthropogenic infrastructure like reservoirs can act as unintended hubs facilitating species dispersal following extreme events like floods, altering community structures. At the biogeochemical scale, climate-induced alterations in nutrient cycling, primary productivity, and carbon sequestration are reshaping ecosystem functioning, particularly in high-latitude and freshwater environments where adaptive capacity is comparatively constrained. Changes in food web architecture and energy transfer efficiency further compromise ecosystem services. This review specifically centers on the biological and ecological mechanisms underlying these climate-driven changes, including organism-level stress responses, shifts in species interactions, and alterations in pathogen dynamics. Recognizing the societal implications and public discourse surrounding climate change underscores the urgency of examining its tangible impacts on sensitive environments, such as estuarine ecosystems, which serve as critical interfaces between terrestrial and marine realms and are thus highly susceptible to both climatic shifts and human influence.
Continue reading ‘Climate change and aquatic ecosystems: impacts on salinity, species survival, and ecological resilience’Temperature, but not acidification, influences the growth and lipid profile of juvenile sand whiting, Sillago ciliata (Cuvier 1829)
Published 18 June 2026 Science ClosedTags: biological response, fish, Indian, mesocosms, morphology, multiple factors, physiology, reproduction, temperature
Seafood provides an essential source of macro- and micronutrients for coastal communities worldwide. Climate change is a key threat to seafood security, altering the sizes, abundances, distributions, physiology and ecological interactions of fisheries species, and increasingly, there is evidence of impacts to seafood nutritional quality. In a 12-week mesocosm experiment, we tested the influence of projected ocean warming and acidification scenarios on the growth and lipid quality of juvenile sand whiting (Sillago ciliata), a popular fisheries species in eastern Australia. The growth of S. ciliata significantly increased (by 61% body weight) under elevated temperature (+3°C) but was not affected by acidification treatment levels. Lipidomic analysis revealed no influence of temperature or acidification on total lipid content or the composition and total proportions of lipid classes and subclasses. However, elevated temperatures significantly impacted the overall composition of fatty acids, including a shift toward higher saturation and a decline in important omega-3 fatty acids. Fish exposed to elevated temperature treatments had more saturated fatty acids than those at control temperatures, along with reduced levels of the valuable omega-3 eicosapentaenoic (C20:5) and docosahexaenoic (C22:6) fatty acids. Despite impacting fatty acid composition in S. ciliata, the increased growth of the juvenile whiting, if sustained into adulthood, under elevated temperatures, may help compensate for the overall availability of essential polyunsaturated fatty acids to support consumer nutritional requirements. These findings contribute to the growing body of evidence on variable climate resilience in nearshore species to future environmental conditions and the implications for the trophic transfer of nutrients in estuarine ecosystems.
Continue reading ‘Temperature, but not acidification, influences the growth and lipid profile of juvenile sand whiting, Sillago ciliata (Cuvier 1829)’Geographic variation in proteomic responses to ocean acidification in a cold-water coral (Balanophyllia elegans)
Published 16 June 2026 Science ClosedTags: biological response, BRcommunity, calcification, corals, laboratory, mesocosms, mortality, physiology
In the face of a rapidly changing climate, assessing organismal responses to future stressors in the context of current, natural exposure to stress could provide key insights to understanding marine ecosystem resilience. I used Balanophyllia elegans, a cold-water, solitary, azooxanthellate coral as a model to better understand how varying oceanographic conditions across its geographic range have shaped its ability to tolerate and potentially adapt to current and future ocean acidification conditions. I collected B. elegans individuals from four sites across 2,500km of their range and subjected them to two pH treatments to investigate site-specific protein expression in response to low pH. Using proteomic analysis, I found that corals from each site responded differentially to low pH, mainly through changes in regulation of metabolism, calcification, and homeostasis-related proteins. Additionally, health condition varied significantly between sites after exposure to low pH, providing further evidence of site-specific responses. These results demonstrate site-specific variation in responses and tolerance to low pH, a pattern that could inform future investigations into environmental-driven adaptive expression. Such site-specific responses highlight the importance of multi-source studies for predicting a species’ ability to navigate future climate changes.
Continue reading ‘Geographic variation in proteomic responses to ocean acidification in a cold-water coral (Balanophyllia elegans)’Coastal phytoplankton response to acidification and warming under differing levels of nutrient availability
Published 12 June 2026 Science ClosedTags: biological response, community composition, mesocosms, multiple factors, nutrients, otherprocess, photosynthesis, phytoplankton, South Pacific
Ocean acidification and warming will alter phytoplankton biomass and composition, yet despite numerous studies, there are few consistent responses on which to base predictions. To determine the responses of chlorophyll-a and phytoplankton size and composition to predicted lower pH (−0.33 to −0.5) alone, and also combined with elevated temperature (+2.5–3.5 °C), two mesocosm experiments were carried out in austral spring and autumn in temperate New Zealand coastal waters. Lower pH alone had no effect on chlorophyll-a in either experiment and, as the treatment pH was lower than the pH minimum recorded in a parallel four-year time series, this lack of response in chlorophyll-a was not attributable to prior in situ exposure. Conversely, chlorophyll-a increased under lower pH and warming in both experiments, with the large (>20 µm) phytoplankton size fraction showing opposing responses under nutrient deplete and replete conditions. Diatom biomass also increased in both treatments when nutrient availability was maintained, with a dominant pennate species Cylindrotheca clostridium emerging. The results highlight the value of contextual time series for experimental interpretation, and also the importance of assessing warming and acidification together using regionally representative nutrient concentrations, for prediction of coastal phytoplankton response to climate change.
Continue reading ‘Coastal phytoplankton response to acidification and warming under differing levels of nutrient availability’Effects of ocean acidification on the growth, shell integrity, and vulnerability to thermal stress and predation in Pacific oysters (Magallana gigas), and bay mussels (Mytilus spp.)
Published 17 April 2026 Science ClosedTags: biological response, laboratory, mesocosms, mollusks, morphology, mortality, multiple factors, North Pacific, predation, temperature
The ocean is absorbing approximately one third of the anthropogenic carbon dioxide (CO₂) emissions to the atmosphere. As a result, the pH of the ocean is declining steadily, a phenomenon known as ocean acidification (OA). This decline in pH and the associated reductions in calcium carbonate saturation states of the water can have widespread consequences for marine life, particularly to calcifying organisms. In this thesis, I aim to understand the effects of OA on the growth, shell integrity, and susceptibility to secondary stressors like heatwaves or predation, of two important shellfish species in British Columbia, Pacific oysters (Magallana gigas) and bay mussels (Mytilus spp.). I also aim to identify potential tipping points beyond which the biological responses of these shellfish to OA rapidly become more pronounced. I reared oysters and mussels in experimental mesocosms, in four pCO₂ treatments for eight-weeks to determine growth. I subsequently exposed these OA-acclimated animals to a secondary stressor by simulating heatwave conditions to assess thermal tolerance, and by introducing a predatory sea star to assess vulnerability to predation. Finally, shell condition was visually assessed, and shells were mechanically crushed to determine integrity. I found that OA decreased the growth of both oysters and mussels. No tipping point was observed for oyster growth, but reduced growth only emerged at the highest levels of OA in mussels. Sensitivity to atmospheric warming was not increased after exposure to acidic conditions for either species, although oysters had a considerably higher thermal tolerance than mussels. Mussel vulnerability to predation did increase, although the relationship was complex and depended on predator size. OA negatively affected shell strength, and possible tipping points emerged for this response metric in both species. Overall, OA was shown to negatively affect both species, but patterns of effect and the presence of potential tipping points depended on the species and the response metric. Understanding how these ecologically and commercially important bivalves are responding to OA is important for understanding how changing ocean chemistry will affect marine ecosystems, and to inform aquaculture managers on mitigation strategies.
Continue reading ‘Effects of ocean acidification on the growth, shell integrity, and vulnerability to thermal stress and predation in Pacific oysters (Magallana gigas), and bay mussels (Mytilus spp.)’Intracellular acid-base regulation mediates a trade-off between shell and somatic growth in a clam under ocean acidification
Published 9 April 2026 Science ClosedTags: biological response, growth, individualmodeling, laboratory, mesocosms, modeling, molecular biology, mollusks, North Pacific, physiology
Highlights
- Clams actively regulate intracellular pH against ocean acidification via CAc
- RNAi confirms CAc’s essential role in H+ efflux, measured by in vivo SIET.
- A CAc-sAC-NKA network forms a conserved regulatory pathway for acid-base balance.
- DEB model shows this pH defense sustains shell linear growth despite metabolic costs.
SUMMARY
Ocean acidification (OA) is predicted to threaten marine bivalves, casting them as passive victims of changing carbonate chemistry. Contributing to a revised understanding, we identified a conserved mechanism for acid-base regulation that supports intracellular resilience. Using the Manila clam Ruditapes philippinarum as a model, this study demonstrated that intracellular pH (pHi) homeostasis under elevated pCO2 was maintained through cytosolic carbonic anhydrase (CAc)-mediated H+ efflux. A causal link was established by combining in vivo scanning ion-selective electrode technique (SIET) with RNA interference (RNAi), where RpCAc knockdown suppressed H+ efflux and compromised pHi. A coordinated regulatory network involving CAc, soluble adenylyl cyclase (sAC), and Na+/K+-ATPase (NKA) was synergistically upregulated, suggesting an evolved adaptive pathway. Dynamic Energy Budget (DEB) modeling, calibrated with experimental data, revealed that this cellular compensation carries a high energetic cost, leading to a significant reallocation of resources: shell growth was maintained, but somatic growth was severely suppressed. These results elucidate a conserved cytoprotective mechanism that enables short-term tolerance of OA at a substantial somatic cost, redefining resilience to include energetic trade-offs.
Continue reading ‘Intracellular acid-base regulation mediates a trade-off between shell and somatic growth in a clam under ocean acidification’Stony coral symbioses show variable responses to future ocean conditions
Published 16 March 2026 Science ClosedTags: adaptation, biological response, BRcommunity, community composition, corals, laboratory, mesocosms, multiple factors, North Pacific, otherprocess, phytoplankton, temperature
Coral reefs support over a quarter of marine species and nearly a billion people worldwide but are also among the ecosystems most threatened by anthropogenic impacts. There is long-standing debate about whether coral symbioses will be disrupted or respond adaptively under future ocean conditions. Using a factorial 2.5-year future-ocean mesocosm experiment across eight coral species representing the major coral lineages, we tracked symbiont community shifts within replicate fragments from the same individual coral. Some corals exhibited stochastic divergence consistent with dysbiosis, whereas others showed deterministic, thermally adaptive shifts. Heat stress generally reduced symbiont diversity and promoted predictable restructuring, supporting deterministic processes under moderate stress but stochastic dysbiosis under extreme conditions. We propose that adaptive and stochastic responses represent endpoints along a continuum of host-orchestrated symbiont sorting. This study bridges coral reef ecology with broader host–microbiome theory, offering an integrated perspective on how symbiotic systems may respond to environmental change.
Continue reading ‘Stony coral symbioses show variable responses to future ocean conditions’Ocean acidification reduces diatom and photosynthetic gene abundance on plastic in an coastal bay mesocosm experiment
Published 25 February 2026 Science ClosedTags: abundance, biological response, BRcommunity, community composition, laboratory, mesocosms, molecular biology, North Pacific, otherprocess, phytoplankton, prokaryotes
Discarded plastics are accumulating in the global ocean and posing threat to marine life. The plastisphere – the community colonizing plastic surfaces – profoundly influences plastic’s environmental behavior, affecting its degradation and entry into marine food webs. Ocean acidification (OA) resulted from anthropogenic CO2 emissions, is also threatening marine ecosystems, but the effect of OA on the structure and ecological function of the plastisphere community remains poorly understood. Here, using a mesocosm experiment, we investigated the effects of OA on the plastisphere colonizing floating PET plastic bottles. The study was conducted using subtropical eutrophic coastal water from Southern China under two CO2 conditions: increased CO2 to 1000 μatm (HC) and ambient CO2 410 μatm (LC). Metagenomic sequencing of the plastic samples, after exposure for 32 days, showed striking changes in relative abundance of eukaryotes and bacteria caused by HC. There was a 75.3 % decrease in eukaryote read abundances at high CO2, most strikingly a 95.6% decrease in the relative abundance of diatoms. In addition, the relative abundance of genes involved in photosystem II light reactions and pigment synthesis decreased under high CO2 conditions. This suggests that OA could reduce the photosynthetic potential within the plastisphere. Shifts in plastisphere community structure and potentially diminished photosynthesis under OA could influence the food chains within plastisphere, plastic degradation, transportation, and carbon cycle involving plastics. Overall, our results suggest that OA can alter the functional ecology of the plastisphere, with potential implications for marine biogeochemical processes and food web dynamics in subtropical eutrophic coastal water.
Continue reading ‘Ocean acidification reduces diatom and photosynthetic gene abundance on plastic in an coastal bay mesocosm experiment’Indo-Pacific coral reef sponge diversity declines under predicted future ocean conditions
Published 19 February 2026 Science ClosedTags: abundance, biological response, BRcommunity, community composition, corals, laboratory, mesocosms, multiple factors, North Pacific, otherprocess, porifera, temperature
Future oceans are predicted to favor groups like sponges over calcifying taxa such as scleractinian corals. Here, we test this hypothesis by examining the development of coral reef communities in experimental mesocosms over 23 months. 85 sponge species among the calcifying class Calcarea (~33%), and non-calcifying Demospongiae (~60%) and Homoscleromorpha (<10%) recruited to warming (+2°C), acidification (-0.2 pH), and warming+acidification (+2°C, -0.2 pH) future ocean treatments. The diversity of calcifying sponges was unimpacted across any treatment, whereas non-calcifying classes showed greatest declines. 57-66% of demosponges decreased under future ocean conditions, and homoscleromorphs were entirely absent from acidified treatments. Through the sponge loop, sponges play a fundamental role in coral reef nutrient cycling, and altered coral reef community composition likely has functional consequences. This study challenges the assumption that non-calcifying species are less impacted and highlights the importance of understanding how community composition may alter ecosystem functioning under future ocean conditions.
Continue reading ‘Indo-Pacific coral reef sponge diversity declines under predicted future ocean conditions’Resilience of the macroalgae Gongolaria barbata under ocean acidification: physiological responses and restoration perspective
Published 3 February 2026 Science ClosedTags: algae, biological response, laboratory, Mediterranean, mesocosms, morphology, photosynthesis, physiology, reproduction, respiration
The increasing CO2 concentration is a major cause of the climate change phenomenon. Concurrently, the same increase is leading to ocean acidification (OA), which is projected to decrease seawater pH by 0.4 units by 2100. Here we investigated the potential impacts of OA on the canopy-forming brown macroalga Gongolaria barbata from the Venice Lagoon. One-year-old individuals were maintained in mesocosms under two pH levels: 8.1 (current ambient value) and 7.7 (the end-of-the-century value predicted under the current scenario of anthropogenic CO2 emissions). The physiological responses of the algae were assessed during the experiment in terms of oxygen production and consumption, and maximal PSII photochemical efficiency. At the end of the experiment, we analyzed the percentage of mature receptacles, algal growth rate and the total polyphenolic content and antioxidant capacity as indicators of the stress response. The significant decrease in polyphenolic content indicates the impairment of the defence mechanisms, which could make the algae more vulnerable to grazing under acidified conditions. Yet, conversely, our results suggest that changes in pH levels do not significantly affect the physiological processes, growth or fertility of the algae. These findings suggest that while OA may weaken defence mechanisms, the preservation of physiological and reproductive functions would still support the potential of G. barbata populations from the Venice Lagoon to act as donor sources for restoration efforts, highlighting their resistance to the acidified conditions expected in the future.
Continue reading ‘Resilience of the macroalgae Gongolaria barbata under ocean acidification: physiological responses and restoration perspective’Asymmetric effects of acidification and warming on foundation species and their predators in the California rocky intertidal zone
Published 11 December 2025 Science ClosedTags: algae, BRcommunity, calcification, laboratory, mesocosms, mollusks, morphology, multiple factors, North Pacific, performance, photosynthesis, respiration, temperature
The effects of climate change on marine organisms act through multiple pathways, as ocean warming and acidification can affect both their physiology and interspecies interactions. Asymmetries in species-specific physiological responses to climate change may alter the strength of interactions, such as those between predator and prey, which will have cascading effects on ecosystem structure. How foundation species and their interactions are affected by climate change will profoundly affect their community due to their dominance. I assessed the physiological responses of two common California rocky intertidal consumer–resource pairs across multiple trophic levels. I measured metabolic rates after four weeks of exposure to a range of nine pH levels (7.2–8.0) at two temperature levels (ambient, +4°C). At the lowest trophic level, I examined the effects of climate change on a primary producer foundation species, Silvetia compressa (golden rockweed), and its herbivore, Tegula eiseni, under differing upwelling regimes in early and late spring. Rockweed responded more to acidification than warming, decreasing photosynthetic rates in early spring and increasing rates during late spring. Their snail consumer, however, responded most strongly to temperature—increasing both respiration rates and calcification under warm conditions in late spring. In addition to species specific responses to climate stressors, the rockweed–snail pair had context-dependent responses based on background environmental conditions. Greater upwelling during late spring, combined with a younger snail population could explain differences in responses between early and late spring. Next, I examined asymmetries between a calcifying foundation species, Mytilus californianus, and its whelk predator, Nucella emarginata. Specifically, mussels were generally resistant to acute exposure to ocean warming and acidification, while whelks were highly sensitive to temperature. Whelks decreased their calcification, respiration, shell extension, and probability of drilling a mussel under warmer conditions. Across both experiments, I observed asymmetries in response to changes in pH and temperature between consumer and resource, which can shift ecosystems between bottom-up and top-down processes. Overall, I showed that mesopredators, such as herbivorous and carnivorous snails, appeared to be the most sensitive to changes in temperature relative to their foundation species prey. Climate change may reshape rocky intertidal communities by altering predation patterns on foundation species, which could either facilitate or threaten the survival of other associated species in a changing environment.
Continue reading ‘Asymmetric effects of acidification and warming on foundation species and their predators in the California rocky intertidal zone’Ocean acidification alters phytoplankton diversity and community structure in the coastal water of the East China Sea
Published 5 December 2025 Science ClosedTags: biogeochemistry, biological response, community composition, laboratory, mesocosms, North Pacific, otherprocess, phytoplankton, primary production, respiration
Anthropogenic CO2 emissions and their continuous dissolution into seawater lead to seawater pCO2 rise and ocean acidification (OA). Phytoplankton groups are known to be differentially affected by carbonate chemistry changes associated with OA in different regions of contrasting physical and chemical features. To explore responses of phytoplankton to OA in the Chinese coastal waters, we conducted a mesocosm experiment in a eutrophic bay of the southern East China Sea under ambient (410 μatm, AC) and elevated (1000 μatm, HC) pCO2 levels. The HC stimulated phytoplankton growth and primary production during the initial nutrient-replete stage, while the community diversity and evenness were reduced during this stage due to the rapid nutrient consumption and diatom blooms, and the subsequent shift from diatoms to hetero-dinoflagellates led to a decline in primary production during the mid and later phases under nutrient depletion. Such suppression of diatom-to-dinoflagellate succession occurred with enhanced remineralization of organic matter under the HC conditions, with smaller phytoplankton becoming dominant for the sustained primary production. Our findings indicate that, the impacts of OA on phytoplankton diversity in the coastal water of the southern East China Sea depend on availability of nutrients, with primary productivity and biodiversity of phytoplankton reduced in the eutrophicated coastal water.
Continue reading ‘Ocean acidification alters phytoplankton diversity and community structure in the coastal water of the East China Sea’Environmental stressors interplay with top-down and bottom-up effects upon shell structure and function of an intertidal marine snail
Published 17 November 2025 Science ClosedTags: biological response, calcification, growth, laboratory, mesocosms, mollusks, morphology, multiple factors, physiology, predation, South Pacific, temperature
Highlights
- Environmental stressors affect shell properties varied across the trophic network.
- OA, OW and predator cues, reduced snail’s shell growth and calcification.
- OA and OW influenced shell structure and resistance more than predator risk.
- Food quality modulates periostracum organic content under OA and OW conditions.
- Biopolymer plasticity aids shell resistance, reducing climate stress vulnerability.
Abstract
Mollusc gastropods have evolved complex shells to protect their soft tissues from biotic and abiotic stress, but the impact of biological and environmental interactions on shell properties is not well understood. This study assessed how the individual and combined effects of increased temperature and pCO2 affect the structural and functional properties in shells of the intertidal snail Tegula atra, considering predator risk from the crab Homalaspis plana and changes in the nutritional quality of its food source, the brown kelp Lessonia spicata. Ocean acidification (OA) and ocean warming (OW) significantly affected growth rate and calcification of snails, with greater impacts under predator risk (top-down) than food quality (bottom-up) influences. FTIR-ATR analyses of the organic composition of shell periostracum indicated that OA conditions increased total organic matter, while polysaccharides, and carbonate content signals showed complex interactive effects under OA and OW conditions, with minor predator cue effects, while the nutritional value of the food source alters polysaccharides and lipids signals. Functional properties (resistance) of the shell material were affected by OA, OW, and predator cues but not by food quality source. These findings provides a novel understanding of how interacting climate stressors and trophic dynamics shape the structural (biomineralization) and functional (biomechanical) resilience of intertidal gastropods.
Continue reading ‘Environmental stressors interplay with top-down and bottom-up effects upon shell structure and function of an intertidal marine snail’Gut microbial community plasticity as a climate shield mediating sea cucumber resilience to ocean acidification and warming
Published 28 October 2025 Science ClosedTags: biological response, BRcommunity, community composition, echinoderms, laboratory, mesocosms, multiple factors, North Pacific, otherprocess, physiology, prokaryotes, temperature
Ocean acidification (OA) and ocean warming (OW) pose escalating threats to marine ecosystems, particularly to benthic organisms, such as sea cucumbers, that play pivotal roles in nutrient cycling and sediment health. Existing studies have mostly focused on the physiological responses of sea cucumbers, yet overlooked the critical roles of both gut microbial communities and metabolites in the host’s responses under environmental stress. Herein, a mesocosm experiment was constructed and analyzed by using integrated gut microbiome and metabolomics approaches to investigate the responses of sea cucumbers Apostichopus japonicus to OA and OW. Results revealed that microbial community plasticity underpins holobiont adaptation, with warming restructuring gut microbiota toward thermotolerant taxa, whereas acidification enriches alkalinity-modulating Rhodobacteraceae and Halioglobus sp.. Metabolomic profiling identified 43 amino acid derivatives that exhibit significantly increased concentrations in the OA and OW groups. These derivatives include upregulated N-methyl-aspartic acid and γ-glutamyl peptides, which stabilize macromolecules and enhance redox homeostasis. Conversely, antioxidative metabolites, such as ergothioneine and L-homocystine, are suppressed, reflecting trade-offs between energy allocation and stress protection. In OW group, the antioxidant synthesis pathway is shifted to energy metabolism related to heat tolerance, whereas in OA group, energy is preferentially used for alkalinity regulation pathways rather than oxidative stress defense. Changes in microbial community structure mechanistically explain the trends in metabolite concentrations, as the proliferation of Vibrio spp. in the OW group drives lysine catabolism, leading to a significant increase in L-saccharopine levels. The reduction of Bacteroidetes in the OA group is correlated with the downregulation of L-homocystine, suggesting that pH-driven microbial interactions are disrupted. These findings demonstrate that gut microbiota reconfigure community structure and metabolic landscapes to buffer hosts against climate stress synergies, highlighting the importance of microbiome-mediated resilience in marine ecosystems under global climate change.
Continue reading ‘Gut microbial community plasticity as a climate shield mediating sea cucumber resilience to ocean acidification and warming’Adaptive phenotypic evolution of Skeletonema costatum to ocean acidification and warming with trade-offs from a multi-year outdoor experiment
Published 11 August 2025 Science ClosedTags: adaptation, biological response, growth, laboratory, mesocosms, multiple factors, otherprocess, photosynthesis, physiology, phytoplankton, temperature
Human-induced climate change is increasing variability in marine environments, significantly affecting marine organisms and ecosystems. While marine diatoms can adapt to ocean acidification and warming in stable laboratory settings, their responses to long-term environmental changes under natural variability remain unclear. To investigate this, we cultivated Skeletonema costatum in outdoor semi-continuous cultures for over 3 years, exposing them to fluctuating natural light and temperature that tracked the in situ sea surface temperatures. We simulated current and future ocean conditions through four treatments: ambient CO2 and temperature (LTLC), elevated CO2 (LTHC), elevated temperature (+4°C, HTLC) and combined increases (HTHC). After 1396 days, we assessed populations in two assay environments (20°C, 400 ppm CO2 and 24°C, 1000 ppm CO2) for adaptations in growth rate, pigment composition and photosynthesis. The HTLC-selected group showed the highest growth rates in the HTHC assay environment, while the LTLC-selected group grew fastest in the LTLC assay environment, indicating adaptive evolution. Furthermore, populations selected under elevated conditions exhibited lower fitness in LTLC environments, highlighting a trade-off and underscoring the complexity of evolutionary adaptation in marine diatoms. Understanding these mechanisms is crucial for predicting phytoplankton dynamics and their role in marine ecosystems, especially in response to climate change.
Continue reading ‘Adaptive phenotypic evolution of Skeletonema costatum to ocean acidification and warming with trade-offs from a multi-year outdoor experiment’Impact of CO2-induced aquatic acidification on environmental DNA and RNA shedding and persistence
Published 5 August 2025 Science ClosedTags: biological response, laboratory, mesocosms, molecular biology, mollusks
Anticipated future increases in CO2 levels are predicted to have a diverse array of lethal and non-lethal effects on the marine ecosystem. While there has been extensive research on the physiological impacts of ocean acidification on marine species, our understanding of how increasing levels of carbon dioxide affect the shedding and decay of environmental DNA and RNA (eDNA/ eRNA) in marine habitats is limited. This may impede the effective adoption of environmental nucleic acid–based molecular tools for monitoring marine biodiversity and detecting rare or invasive species. In the present study, we conducted mesocosm experiments to determine the shedding and decay rate constants of eDNA and eRNA in M. gigas (Magallana [Crassostrea] gigas) using mitochondrially encoded tRNA leucine 1 (mt-tl1) marker at various partial pressures of CO2 in seawater. To our knowledge, this is the first study manipulating seawater pH using CO2. We developed a sensitive and specific quantitative PCR-based assay to detect M. gigas eDNA and eRNA. Higher CO2 levels increased shedding rates, indicating greater organism stress and biological effects on oysters. Additionally, increased CO2 accelerates DNA and RNA decay, suggesting that ocean acidification may impact the reliability of eDNA-based biodiversity monitoring. Furthermore, eRNA displayed lower steady-state concentrations and a shorter persistence time in comparison to eDNA, as is consistent with known biochemical properties of the molecules. These findings are presented in the context of previous work that adjusted pH through acid–base adjustment and temperature and highlight the importance of considering ocean acidification caused by differing CO2 levels when using molecular tools for marine conservation and fisheries management.
Continue reading ‘Impact of CO2-induced aquatic acidification on environmental DNA and RNA shedding and persistence’Timing of calcification and environmental variability determine pH proxy fidelity in coastal calcifying macroalgae
Published 21 July 2025 Science ClosedTags: algae, biological response, chemistry, field, mesocosms, North Atlantic, paleo, physiology, South Pacific
Long-lived calcifying marine biota are increasingly used as paleo-archives for reconstructing ocean pH. They enable exploration of the rate and magnitude of ocean acidification in shallow-water ecosystems serving as proxies for environmental pH reconstruction. However, shallow water systems often have highly variable carbonate chemistry, and the impact of this on the accuracy of pH reconstructions from long-lived marine calcifiers is not known. In particular, a better understanding of the timing of calcification with respect to environmental pH cyclicity is needed. To test the fidelity of coastal environmental pH proxies, we assessed the synchronicity between calcification and in situ diel carbonate chemistry in a tropical (One Tree Island, Great Barrier Reef, Australia) and a temperate (Loch Sween, Scotland) location using calcifying macroalgae (rhodolith-forming coralline algae) as a model system. Calcification occurred primarily during daylight hours, meaning a recording bias was introduced when compared to the full diel pH range (< 0.02 pH units). This bias resulted in pH offsets up to 0.043 pH units over the period 1860–2020, representing up to 34% of the projected pH change from 1860 in the tropics and up to 1.8% in temperate latitudes. Therefore, when proxy records are used to extend modern instrumental records of pH, we find that this may lead to bias, indicating daytime, nighttime, and full diel pH records should be assessed separately. We suggest that temporal pH cycles should be characterized at a local scale to enable incorporation of potential biases in the application of calcifying marine macroalgae to reconstruct pH change.
Continue reading ‘Timing of calcification and environmental variability determine pH proxy fidelity in coastal calcifying macroalgae’Combined effects of ocean acidification and warming on phytoplankton productivity and community structure in the coastal water of Southern East
Published 17 July 2025 Science ClosedTags: biological response, community composition, laboratory, mesocosms, molecular biology, multiple factors, North Pacific, otherprocess, photosynthesis, physiology, phytoplankton, temperature
Highlights
- Ocean warming partly offsets acidification-driven impacts on primary productivity in a southern coastal water of China.
- Acidification alters phytoplankton communities with increased proportions of dinoflagellates and reduced that of diatoms.
- Combination of warming and acidification reduced overall microbial diversity in the coastal water.
Abstract
Progressive global ocean changes, including ocean acidification and warming, are expected to impact ecosystems differentially due to regional environmental differences that govern biogeochemical and ecological processes. In this study, we investigated the impacts of ocean acidification and warming on the phytoplankton community and primary productivity in the southern coastal water of the East China Sea by running land-based mesocosms controlled under current atmospheric pCO2 (∼430 μatm) and projected levels for the year 2100 (∼1000 μatm, HC, High CO2) at 27°C (ambient) and 30°C (warming, HT, High Temperature). Our results indicate that warming, acidification, and their combined effects (HCHT) initially enhanced community biomass as determined by chl a concentration; however, this effect diminished over time, ultimately resulting in lower biomass density compared to the control in later stages. Primary productivity per volume of seawater in the HT and HCHT treatments was initially suppressed but increased in the later stages compared to the control group, whereas the HC treatment appeared to suppress it consistently. While higher effective photochemical efficiency and non-photochemical quenching coincided with higher photosynthetic carbon fixation per chlorophyll an under the HT and HCHT treatments, their decline under the HC after the acclimation was concurrent with decreased photosynthetic carbon fixation. Analysis of 18S rDNA revealed that diatoms and dinoflagellates dominated under the treatments of HC, HT, and HCHT, but compared to the control, the proportion of diatoms decreased by 23%, 14%, and6 %, while that of dinoflagellates increased by 19%, 9%, and 11%, respectively, under the corresponding treatments. Plankton richness increased under warming, while diversity declined, particularly with combined warming and acidification, highlighting community sensitivity to the stressors. With reference to heterotrophic microbes, the relative abundance of Basidiomycota increased by 16%–18% under HT or HCHT, along with insignificant impacts on prokaryotic communities based on 16S rDNA analysis. In conclusion, the combination of ocean acidification and warming treatment during the experimental period ultimately reduced the phytoplankton biomass density and altered the microbial community structure.
Continue reading ‘Combined effects of ocean acidification and warming on phytoplankton productivity and community structure in the coastal water of Southern East’Infaunal bivalves exhibit resilience to ocean acidification but remain sensitive to food supply
Published 26 June 2025 Science ClosedTags: biological response, chemistry, dissolution, laboratory, mesocosms, mollusks, morphology, multiple factors, physiology, South Pacific
Soft-sediment habitats are crucial for marine coastal ecosystems, supporting diverse biodiversity both above and below the sediment. Ocean acidification, driven by rising CO2 and nutrient influx, enhances heterotrophic metabolism, raising CO2 levels and lowering pH. These alterations complicate the dynamics of tidal flat, emphasizing the need for further research into their impact on biodiversity. Within these ecosystems, deposit- and suspension-feeding bivalves play crucial roles. Tagelus dombeii, a bivalve mollusc found in soft sediments, exhibits burrowing behavior linked to food supply and is of significant commercial value in southern Chile. This study assessed the response capacity of T. dombeii to key stressors associated with global ocean change, such as ocean acidification and food availability. Our results revealed significant differences in pH levels between the water column and pore water from the sediment in experimental mesocosms. T. dombeii was affected by ocean acidification and food availability in terms of its morphological traits (i.e. length, width, height and growth rate), while oxygen consumption was influenced only by the interaction between acidification and food supply. Notably, heart rate remained constant but increased when food supply was low. Our study suggests that T. dombeii exhibits partial tolerance to variations in seawater pH and carbonate chemistry, possibly due to its natural exposure to acidic pore water, but it is sensitive to food availability. These plastic physiological responses suggest that T. dombeii may be less vulnerable to future global change scenarios, demonstrating potential resilience and ecological success in its natural habitat.
Continue reading ‘Infaunal bivalves exhibit resilience to ocean acidification but remain sensitive to food supply’
