Pelagic calcifying protists such as coccolithophores and foraminifera represent an important microbial component of the marine carbon cycle. Although their calcitic shells are preserved in oceanic sediments over millennia, their resilience in the future decades is uncertain. We review current literature describing the response of calcifying protists to ocean acidification and temperature warming. We examine these key ecological and biogeochemical processes through the cellular perspective, exploring the physiological, metabolic, and molecular responses of calcifying protists. Ocean acidification is a chemical process that takes place in the seawater outside the cell, whereas protists calcify inside a modified cellular microenvironment. The function of these calcification compartments depends on cellular response to ocean acidification, such as maintaining pH homeostasis. The response of calcifying protists to ocean acidification and temperature warming is species-specific, with no unifying trends but rather a range of sensitivity levels. Coccolithophores and foraminifera display physiological sensitivity that may hamper their ecological success in comparison to non-calcifying species. Yet, certain species may be more adaptable, especially when comparing to highly vulnerable calcifying molluscs as pteropods. As the molecular machinery mediating cellular calcification is not fully resolved, as well as the functional role of the calcitic shell, our ability to predict the fate of calcifying microorganisms in a warmer, more acidic ocean is limited. We propose the urgent need to expand the study of these model systems by advancing cell biology approaches, to better understand the impact of climate change on microbial food webs in the ocean.
Continue reading ‘Uncertain fate of pelagic calcifying protists: a cellular perspective on a changing ocean’Archive Page 48
Uncertain fate of pelagic calcifying protists: a cellular perspective on a changing ocean
Published 26 February 2025 Science ClosedTags: adaptation, biological response, molecular biology, otherprocess, physiology, protists, review
Vertical expansion of aragonite undersaturated waters in the Canada Basin of the Arctic Ocean from 2003 to 2019
Published 25 February 2025 Science ClosedTags: Arctic, chemistry, field
Abstract
The Canada Basin of the Arctic Ocean is considered the region of the world’s open ocean most susceptible to the Ocean Acidification (OA). This study examines progression of OA in the Canada Basin, focusing on expansion of surface and subsurface aragonite undersaturated waters (USW). Surface USW thickness increased from 0 m in 2003 to 19 ± 2 m in 2019. This change was due to freshening until 2012, and then due to increased uptake of anthropogenic CO2 after 2012. In the subsurface layer, USW thickness increased from 94 ± 6 m in 2003 to 136 ± 11 m in 2019. This change is primarily attributed to OA in upstream shelf regions, driven by increased CO2 uptake and respiration, with some contribution from thickening in the Pacific Winter Water layer. The combined thickening of surface and subsurface USW layers increased the percentage of USW in the 0–250 m water column from 38 ± 3% in 2003 to 62 ± 5% in 2019. Because of the concurrent deepening of the water masses due to the enhanced Beaufort Gyre, the replacement of oversaturated water to USW occurred mostly at the subsurface layer below 190 m. The thickness of the oversaturated layer between surface and subsurface USWs remained almost unchanged. If Beaufort Gyre weakens in the future, it would bring subsurface USW shallower, potentially affecting marine life.
Key Points
- Long-term observations revealed expansion of aragonite undersaturated waters (USW) in the Canada Basin of the Arctic Ocean
- Increase in USW thickness was mainly due to physical processes in the earlier period and biogeochemical processes in the later period
- Although USW thickened in surface and subsurface layers, the thickness of the oversaturated layer between them did not change
Plain Language Summary
The Canada Basin of the Arctic Ocean is particularly vulnerable to a process called Ocean Acidification (OA), which makes the water less suitable for marine life. This study focuses on how OA has been changing in this area, especially the expansion of certain types of problematic water (called “aragonite undersaturated waters” or USW) in the surface and subsurface layers. At the surface, this less hospitable USW has become thicker, going from essentially nothing in 2003 to 19 ± 2 m deep in 2019. This change was due to the water becoming less salty (freshening) and increased absorption of carbon dioxide (CO2). In the subsurface layer, USW also got thicker, increasing from 94 ± 6 m in 2003 to 136 ± 11 m in 2019. This happened because of OA driven by more atmospheric CO2 absorption and increased respiration in the upstream shallow shelf areas. The combined increase in the thickness of these surface and subsurface USW layers means that a larger portion of the water now consists of this less hospitable USW, going from 38 ± 3% in 2003 to 62 ± 5% in 2019. If physical conditions change in the future, the less suitable subsurface water would be brought closer to the surface, potentially impacting marine life.
Continue reading ‘Vertical expansion of aragonite undersaturated waters in the Canada Basin of the Arctic Ocean from 2003 to 2019’Carbonate and nutrient dynamics in a Mississippi River influenced eutrophic estuary
Published 25 February 2025 Science ClosedTags: biogeochemistry, chemistry, field, North Atlantic
There is limited information on how the nutrient and freshwater input affects water column carbonate chemistry in the estuaries along the northern Gulf of Mexico. In this study, we assess the seasonal and spatial variability in carbonate chemistry in the Barataria Basin, a eutrophic estuary adjacent to the mouth of the Mississippi River. Eleven stations were sampled along a salinity gradient during the winter (January), spring (April), summer (July), and fall (October) of 2021. Surface and bottom water samples were collected for the analyses of dissolved inorganic carbon (DIC); total alkalinity (TA); and nitrite plus nitrate (NO2 + NO3), phosphate (PO4), and dissolved silica (SiO4). Dissolved CO2 (pCO2) was measured in the surface water. Seasonal surface DIC and TA values ranged from 1553 to 2582 μmol kg−1 and 1217 to 2217 μmol kg−1, respectively. DIC and TA varied seasonally and showed an increasing trend from fresh stations to saline stations. The highest DIC and TA values were observed during the fall season, likely due to the increased contribution of DIC and TA from adjacent marshes as a result of enhanced porewater exchange. In contrast to DIC and TA, pCO2 decreased with the increase of salinity. The seasonal and spatial patterns in carbonate chemistry could not be explained solely by physical mixing and reflected complex interactions between biogeochemical processes driven by nutrient supply and temperature as well as tidal flushing and material exchanges with adjacent marshes.
Continue reading ‘Carbonate and nutrient dynamics in a Mississippi River influenced eutrophic estuary’The nasal microbiota of two marine fish species: diversity, community structure, variability and first insights into the impacts of climate change-related stressors
Published 25 February 2025 Science ClosedTags: biological response, BRcommunity, community composition, fish, laboratory, molecular biology, multiple factors, otherprocess, prokaryotes, temperature
Vertebrate nasal microbiota (NM) plays a key role regulating host olfaction, immunity, neuronal differentiation, and structuring the epithelium. However, little is known in fish. This study provides the first comprehensive analysis of the NM in two marine fish species, the European seabass and the Atlantic cod. Given its direct environmental exposure, fish NM is likely influenced by seawater fluctuations. We analysed the community structure, specificity regarding seawater, and interindividual variability of 32 to 38 fish reared under ambient conditions. Additionally, we conducted an experiment to investigate the influence of acidification and a simplified heatwave on cod NM (3 fish per replicate). High-throughput 16S rRNA sequencing revealed species-specific NM communities at the genus-level with Stenotrophomonas and Ralstonia dominating seabass and cod NM, respectively. This suggests potential habitat- or physiology-related adaptations. The most abundant bacterial genera in seabass NM were also present in seawater, suggesting environmental acquisition. Alpha diversity was highest in Brest seabass NM and variability greatest in Tromsø cod NM. Simulated climate change-related scenarios did not significantly alter cod NM structure. We propose a minimum of 13 cod rosettes per replicate for future studies. This research establishes a foundation for understanding marine fish NM and its response to environmental changes.
Continue reading ‘The nasal microbiota of two marine fish species: diversity, community structure, variability and first insights into the impacts of climate change-related stressors’Blue dot: mussels and a scientific detective story at Bodega Marine Lab and ocean acidification mapping
Published 25 February 2025 Media coverage ClosedHost Dave Schlom is joined by two researchers who have connections to UC Davis’s Bodega Marine Laboratory on the Northern California coast.
Emily Longman, now a marine biologist at the University of Vermont, was a leader in a detective story with roots in UC in the days leading up to World War II.
Two young undergrads did a study of mussel colonies at Bodega in 1941. Their unpublished paper was found recently and Longman led a team to see how the mussel colony had changed in the course of 80 years.
Astonishingly, they found that while mussels are struggling on parts of the California coast, they are thriving at the original study site!
Then, UC Berkeley Professor Rachel Carlson visits with Dave to discuss her work on mapping ocean acidification along the Pacific coast and its implications for marine life as our climate changes.
Continue reading ‘Blue dot: mussels and a scientific detective story at Bodega Marine Lab and ocean acidification mapping’Environmental speaker series presents: integrated social and ecological science for ocean acidification
Published 25 February 2025 Events ClosedWhen: Thu, Mar 6 2025, 4:30 – 5:20pm
Location: Online: Zoom; In-Person at WWU: Academic West 204
Description: This place-based collaborative effort to understand, anticipate, and prepare for ocean changes affecting natural and human systems owes its success to how oceanographic, ecological, and social scientists and tribal community partners co-designed and co-produced the project. Our goal was to provide an assessment of coupled social-ecological vulnerability to effects from ocean acidification based on new social science and a synthesis of existing data and model projections relevant to the Olympic Coast, its biological resources, and its inhabitants. We outlined eight objectives to guide our project, developing areas of strong integration, including drawing from Indigenous knowledge to inform social science understanding, and drawing on these two systems of knowledge for guiding selection of species of focus for biological risk assessment, with feedback to community preparation and adaptation actions. I will focus on ecological elements of the risk assessment but stress its utility in the context of the social science.
The Environmental Speaker Series is free and open to the public. Talks are held each Thursday at 4:30pm in Academic Instructional Center West, room 204. Join us at WWU or online on Zoom!
Continue reading ‘Environmental speaker series presents: integrated social and ecological science for ocean acidification’Resilient mantle, vulnerable shell: ocean acidification’s impact on juvenile pen shell Atrina maura
Published 24 February 2025 Science ClosedTags: biological response, laboratory, mollusks, morphology, North Pacific, physiology
Highlights
- OA does not affect the mantle tissue structure.
- OA influences shell growth but does not impact the shell index.
- OA produces malformation and dissolution of the calcite prismatic and nacre layers of juvenile A. maura.
Abstract
Ocean acidification results from the accumulation of CO2 in seawater. Predictions indicate a pH decrease of 0.3–0.5 units by the year 2100 and 0.7 units by the year 2300. The effects of OA vary among species, exposure time, physiological limits, and short-term adaptability. This phenomenon can be exacerbated in many coastal marine habitats due to nutrient inputs, upwelling events, and terrestrial sources of acidity. This study analyzed the effects of pH reduction on the shell and mantle tissue structure of the juvenile pen shell (Atrina maura) living in coastal bay where the natural pH is 7.8. These organisms were exposed to a reduction of pH (7.5) for 40 days. Scanning electron microscopy (SEM) analysis of the shells revealed signs of malformation and dissolution of the calcite prismatic layer and the nacre layer at acidic pH (7.5 ± 0.2) compared to controls (7.8 ± 0.1) throughout the experiment. However, shell growth increased 13.95 % after CO2 injection after 40 days of exposure, while the shell index and the mantle tissue remained unaffected any of the times evaluated. The results suggest that A. maura, a species naturally exposed to acidic environments, may experience effects from pH reductions primarily in their shell microstructure, while mantle morphology remains unaffected. The results obtained here prove that resilience of marine species, such as A. maura, can be compromised by ocean acidification (OA), highlighting the importance of continued exploration in this field to better understand the broader implications of OA on marine ecosystems.
Continue reading ‘Resilient mantle, vulnerable shell: ocean acidification’s impact on juvenile pen shell Atrina maura’Metabolomic and phenotypic effects of ocean acidification on cuttlefish differ across early life stages
Published 24 February 2025 Science ClosedTags: biological response, laboratory, mollusks, morphology, North Atlantic, physiology, reproduction
Highlights
- Low pH conditions delay the timing of hatching and reduce hatching success of cuttlefish
- Low pH conditions impact cuttlefish egg swelling but not hatchling size
- The maximum rate of O2 consumption is not altered in response to low pH exposure
- Metabolome suggests a metabolic depression in embryos exposed to seawater pH below 7.54
- Metabolic stress due to hatching event exceeds pH effect on metabolite profile
Abstract
Ocean acidification (OA) affects the physiology and behaviour of some marine organisms, impacting their development and metabolism during vulnerable early-life stages. Among them, the embryo of the cuttlefish develops for about two months in encapsulated eggs with harsh perivitelline conditions of hypoxia and hypercapnia, potentially worsened by OA. In this study, common cuttlefish Sepia officinalis embryos and juveniles, were exposed to five pH conditions (pHT 8.08 to 7.43). Growth, development and metabolite profiles were explored during the embryonic development period up to 10 days-post-hatching. Our results show delayed embryonic development and decreased hatching success at pH 7.43, but no effect on juvenile weight upon hatching. The 1H Nuclear Magnetic Resonance (NMR) spectroscopy revealed that decreasing pH affected metabolites profiles in embryos until a metabolic suppression was observed at pH 7.43. The O2 consumption in 10d-old juveniles did not change with pH whereas metabolites indicated a switch to anaerobic metabolism under low pH. Overall, our results suggest that the transition from the encapsulated embryonic stage to the free juvenile life shapes a metabolomic reprogramming more drastically than ocean acidification.
Continue reading ‘Metabolomic and phenotypic effects of ocean acidification on cuttlefish differ across early life stages’Interactive effects of elevated atmospheric CO2 and UV-B radiation: a multi-level study on marine diatom Skeletonema pseudocostatum
Published 24 February 2025 Science ClosedTags: biological response, growth, laboratory, light, multiple factors, photosynthesis, physiology, phytoplankton
Highlights
- Combined effects of UVB radiation and increased atmospheric CO2 was assessed on Skeletonema pseudocostatum.
- Additive, synergistic and antagonistic effects were characterized based on modified independent action (IA) model.
- The combined effects on S. pseudocostatum were dose-dependent and target-specific.
- Additivity was most common, synergy occurred in ROS and growth, while carotenoids content reduced antagonistically.
- An effect pathway was developed to characterize the propagation of combined effects across t biological levels.
Abstract
Climate change as a result of increases in greenhouse gas emissions, such as CO2, is causing significant alteration in global environmental conditions, including ocean acidification (OA). Although the depletion of the ozone layer has reduced, the penetration of ultraviolet-B (UVB) radiation into the oceans still remains an environmental factor that may potentially enhance the effects of OA on biota. Improved understanding of the complex interactions between multiple stressors, such as UV-B radiation and increased CO2 levels, is thus important for safeguarding ecosystems and developing effective conservation and management strategies. A 72 h experiment was carried out to investigate the combined effects of UVB irradiance (0.5 W m−2) and varying CO2 levels (350, 500, 1000 ppm) on the diatom Skeletonema pseudocostatum. The study aimed to characterize the potential combined effects at different levels of biological organization, including ROS formation, lipid peroxidation (LPO), photosynthesis, pigments, oxidative phosphorylation (OXPHOS) and growth. The findings indicate that exposure to elevated CO2 (500 ppm) alone resulted in increased total carotenoid content and growth of S. pseudocostatum, but did not significantly impact photosystem efficiency, oxidative stress, and OXPHOS. Sole UVB exposure induced oxidative stress, inhibited photosynthesis and OXPHOS processes, and suppressed growth in S. pseudocostatum. However, when co-exposed with CO2, synergistic impacts were observed for reactive oxygen species (ROS), lipid peroxidation (LPO), and growth, while carotenoids were reduced in an antagonistic manner. A putative impact pathway was proposed as an initial effort to characterize the combined effects of these stressors under proposed future marine OA scenarios involving elevated CO2.
Continue reading ‘Interactive effects of elevated atmospheric CO2 and UV-B radiation: a multi-level study on marine diatom Skeletonema pseudocostatum’Effect of thermal and non-thermal processes on the variability of ocean surface pCO2 and buffering capacity in the North Indian Ocean
Published 24 February 2025 Science ClosedTags: biogeochemistry, chemistry, Indian, modeling, regionalmodeling
Highlights
- A coupled atmosphere–ocean-biogeochemistry model is customised for NIO.
- High surface pCO2 in upwelling regions of NIO are controlled by non-thermal processes.
- Surface pCO2 changes in upwelling regions of NIO are more sensitive to changes in DIC.
- Diffusion, CO2 flux and Phytoplankton uptake primarily control DIC variability in NIO.
Abstract
The oceans have absorbed nearly 30% of the anthropogenic CO2 that alters the ocean carbon chemistry. The oceanic processes are highly complex, which mandate approaches that couple its physical, chemical and biological states. Here, we use a coupled atmosphere–ocean-biogeochemistry model, incorporating spatially and temporally varying atmospheric CO2 to simulate the north Indian Ocean (NIO) carbon dynamics for the period 2013–2020. We assess the seasonal variability of Dissolved Inorganic Carbon (DIC), total Alkalinity (ALK), ocean surface pCO2 and buffering capacity. To assess the mechanisms that control carbon dynamics in the region, we segregate the ocean surface pCO2 into temperature-driven (thermal) and bio-physical processes induced (non-thermal) pCO2. We find that the thermally driven pCO2 is dominant in summer (June, July, August and September; JJAS), but the non-thermal component in winter (December, January and February; DJF) in the northern Arabian Sea (AS). The northern AS is characterised by a deep mixed layer and convection-induced vertical mixing during winter. DIC from the subsurface layer is uplifted to the surface, which results in high ocean surface pCO2 in winter. Off the Oman coast, the non-thermal processes control the surface pCO2 in summer. In the northern bay, the thermal component of pCO2 is dominant in summer and non-thermal component is prominent in winter as in northern AS, but their magnitudes are lower due to large riverine flux. The budget analysis reveals strong influence of diffusion, CO2 flux and biological processes in controlling DIC variability in NIO. Low buffering capacity in upwelling regions indicates that pCO2 changes are more sensitive to changes in DIC, primarily due to the upwelled DIC-rich surface waters. Therefore, it results in a reduced ability to absorb CO2. This warrants the need to address recent changes in carbon dynamics in response to the increased levels of atmospheric CO2.
Continue reading ‘Effect of thermal and non-thermal processes on the variability of ocean surface pCO2 and buffering capacity in the North Indian Ocean’High-resolution temporal assessment of physicochemical variability and water quality in tropical semi-enclosed bays and coral reefs
Published 24 February 2025 Science ClosedTags: biological response, BRcommunity, chemistry, community composition, corals, field, North Atlantic, otherprocess
Highlights
- Mangrove, seagrass, and coral habitats are at risk from global and local stressors
- We assessed >20 (a)biotic parameters and pollution at high temporal resolution
- Strong diel and seasonal variability was recorded in semi-enclosed bays
- The bays showed higher nutrient levels and ecotoxicological risks than nearby reefs
- A water quality monitoring framework for reef-associated habitats is provided
Abstract
Tropical coastlines featuring mangrove, seagrass, and coral habitats are of immense ecological and socio-economic importance, supporting biodiversity, carbon storage, coastal protection, fisheries, and tourism. However, climate change, coastal development, and low water quality increasingly threaten these interconnected coastal ecosystems, particularly in semi-enclosed bays where the impacts of these stressors are often amplified. Yet, physicochemical conditions are rarely assessed at sufficient temporal resolution (i.e., diel and seasonal variation) and time-integrated pollution monitoring is rarely performed. Here, we used a multi-disciplinary approach to assess >20 abiotic parameters characterizing two mangrove- and seagrass-dominated inland bays and two nearby coral reefs in Curaçao (southern Caribbean) during the cool, dry season and warm, wet season. This was combined with time-integrated pollution monitoring using bioindicators to assess nutrients and trace metal pollution (inland bays only), and passive samplers and bioassays to assess organic chemical pollution (all four sites) during the wet season. This approach revealed a previously undocumented extent of strong diel and seasonal environmental variability in Curaçao’s inland bays, with temperature, pH, and dissolved oxygen frequently reaching values predicted under moderate-to-severe future climate scenarios as outlined by the IPCC (2021). In addition, the inland bays had greater nutrient concentrations (especially ammonium) and potential ecotoxicological risks than the nearby reefs during the wet season due to run-off and anthropogenic activities. These findings emphasize the importance of high-resolution monitoring to understand risks across appropriate temporal scales and establish an environmental baseline against which future monitoring can be benchmarked. Moreover, our study provides a robust water quality assessment framework that can be used by natural resource managers to monitor reef-associated habitats and conserve their high ecological and socio-economic value. Overall, our work highlights the urgent need to improve monitoring, water quality, and protection of these valuable reef-associated habitats.
Continue reading ‘High-resolution temporal assessment of physicochemical variability and water quality in tropical semi-enclosed bays and coral reefs’Assessing benthic invertebrate vulnerability to ocean acidification and de-oxygenation in California: the importance of effective oceanographic monitoring networks
Published 21 February 2025 Science ClosedTags: biological response, chemistry, crustaceans, echinoderms, fisheries, methods, multiple factors, oxygen, policy, review
Greenhouse gas emissions from land-use change, fossil fuel, agriculture, transportation, and electricity sectors expose marine ecosystems to overlapping environmental stressors. Existing climate vulnerability assessment methods analyze the frequency of extreme conditions but often minimally consider how environmental data gaps hinder assessments. Here, we show an approach that assesses vulnerability and the uncertainty introduced by monitoring data gaps, using a case study of ocean acidification and deoxygenation in coastal California. We employ 5 million publicly available oceanographic observations and existing studies on species responses to low pH, low oxygen conditions to calculate vulnerability for six ecologically and economically valuable benthic invertebrate species: red sea urchin (Mesocentrotus franciscanus), purple sea urchin (Strongylocentrotus purpurpatus), warty sea cucumber (Apostichopus parvimensis), pink shrimp (Pandalus jordani), California spiny lobster (Panulirus interruptus), and Dungeness crab (Metacarncinus magister). Further, we evaluate the efficacy of current monitoring programs by examining how data gaps heighten associated uncertainty. We find that most organisms experience low oxygen (<35% saturation) conditions less frequently than low pH ( < 7.6) conditions. It is only deeper dwelling (>75 m depth) life stages such as Dungeness crab adults and pink shrimp embryos, juveniles, and adults that experience more frequent exposure to low oxygen conditions. Adult Dungeness crabs experience the strongest seasonal variation in exposure. Though these trends are intriguing, exposure remains low for most species despite well-documented pH and oxygen declines and strengthening upwelling in the central portions of the California Current. Seasonal biases of data collection and sparse observations near the benthos and at depths where organisms most frequently experience stressful conditions undermine exposure estimates. Herein we provide concrete examples of how pink shrimp and Dungeness crab fisheries may be impacted by our findings, and provide suggestions for incorporating oceanographic data into management plans. By limiting our scope to California waters and assessing the limitations presented by current monitoring coverage, this study aims to provide a granular, actionable framework that policymakers and managers can build from to prioritize targeted enhancements and sustained funding of oceanographic monitoring recommendations.
Continue reading ‘Assessing benthic invertebrate vulnerability to ocean acidification and de-oxygenation in California: the importance of effective oceanographic monitoring networks’Transcriptomic reaction norms highlight metabolic depression as a divergence in phenotypic plasticity between oyster species under ocean acidification
Published 21 February 2025 Science ClosedTags: adaptation, biological response, laboratory, molecular biology, mollusks, mortality, otherprocess, physiology
Ocean acidification occurs at a rate unprecedented for millions of years, forcing sessile organisms, such as oysters, to respond in the short term by relying on their phenotypic plasticity. Phenotypic plasticity has limits, tipping points, beyond which species will have to adapt or disappear. These limits could be related to the adaptation of species to different habitat variabilities. Here we expose juvenile pearl oysters, Pinctada margaritifera, to a broad range of pH and determine the response at the gross physiological, lipidome and transcriptome levels. Thus, we identify its high tolerance with low tipping points at pH 7.3-6.8 below which most physiological parameters are impacted. We then compare the transcriptomic reaction norms of the tropical subtidal P. margaritifera, with those of an intertidal temperate oyster, Crassostrea gigas, reusing data from a previous study. Despite showing similar tipping points with C. gigas, P. margaritifera exhibits strong mortalities and depletion of energy reserves below the tipping points, which is not the case for C. gigas. This divergence relies mainly on the induction of metabolic depression, an adaptation to intertidal habitats in C. gigas, but not in P. margaritifera. Our method makes it possible to detect divergences in phenotypic plasticity, probably linked to the species’ specific life-history strategies related to different habitats, which will determine the survival of species to ongoing global changes. Such an approach is particularly relevant for studying the physiology of species in a world where physiological tipping points will be increasingly exceeded.
Continue reading ‘Transcriptomic reaction norms highlight metabolic depression as a divergence in phenotypic plasticity between oyster species under ocean acidification’Transcriptome and lipidome integration unveils key mechanisms constraining bivalve larval sensitivity in an acidifying sea
Published 21 February 2025 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, North Pacific, physiology, reproduction
Highlights
- OA inhibits key ion transport required for larval calcification.
- OA induces major remodeling of membrane lipids in larvae.
- OA exerts distinct inhibitory mechanisms on larval shell formation.
Abstract
The intensity, frequencye and duration of seawater acidification in coastal seas have already surpassed projections for open oceans. Bivalve larvae are extremely sensitive to intensifying coastal seawater acidificaiton during their initial shell building, a critical period constraining recruitment success and population maintenance, but underlying mechanisms of larval shell formation sensitivity to acidification remain largely debated. Here, we performed an integrated analysis of the transcriptome and lipidome of trochophore of Ruditapes philippinarum to compare the core molecular responses involved in initial shell formation under ambient (pH 8.1), moderately (pH 7.7), and severely (pH 7.4) acidified conditions. Ocean acidification (OA) affected the ion transport efficiency by inhibiting gene expression of key ion transporters, thereby inhibiting initial shell formation, but the gene downregulation in the moderate exposure group was more significant. OA also induced major membrane lipid remodeling in larvae, which also significantly affected the ion transport efficiency. The TAG content of larvae which sustained the energy supply for active transport of calcification substrates and synthesis of organic matrix in the severe exposure group was significantly reduced. Overall, OA inhibited the formation of the initial larval shell, but different levels of OA had different inhibitory mechanisms on the initial larval shell formation, and the present study also further identified the role of lipids in initial shell formation, which can provide a theoretical basis for for a more accurate and comprehensive assessment of the impact of OA on bivalve calcification in an acidifying ocean.
Continue reading ‘Transcriptome and lipidome integration unveils key mechanisms constraining bivalve larval sensitivity in an acidifying sea’Adaptive resilience of sea urchins against seawater acidification: a study on egg quality and offspring performance within a volcanic vents area
Published 20 February 2025 Science ClosedTags: adaptation, biological response, echinoderms, field, multiple factors, otherprocess, reproduction, toxicants, vents
Highlights
- Sea urchins were collected within and outside a volcanic carbon vents area
- Egg quality was investigated revealing differences in size and energetic profile
- Offspring performances were tested at 2 pH levels both with and without herbicide
- Sea urchins from the Vents area showed better offspring performance
- Glyphosate-AMPA mixture caused additional but limited effects compared to pH.
Abstract
Local adaptation plays a critical role in an organism’s ability to survive and reproduce in diverse environmental conditions, potentially improving an organism’s response to stressful conditions such as ocean acidification or pollution. In this study, the effects of lower pH coupled with the presence of environmental contaminants were assessed on sea urchins (Paracentrotus lividus) collected outside and inside a volcanic CO2-vent system, where the mean ambient pH is 8.1 and 7.7, respectively.
Both groups of sea urchins were spawned, and offspring were reared at pH 8.1 and 7.7, and in the presence or absence of a mixture of 100 μg/L of glyphosate and its main metabolite aminomethylphosphonic acid. Offspring performance metrics (development, abnormalities, and growth) were investigated under the different exposure conditions. The exposure to reduced pH affected the development and larval growth in echinoplutei obtained from adults of both sites, although to a different extent. Chemicals mixture had an additive effect in slowing embryo development.
Results revealed that sea urchins living within the lower pH Vents area exhibited significantly higher egg quality, which likely enhanced embryonic development, reduced abnormalities, and increased larval size compared to their counterparts outside the Vents system, both in the presence and absence of contaminants. Findings suggest that sea urchins living within the CO2-Vents system developed adaptations to thrive under lower pH conditions. Elevated egg quality and improved offspring performance suggest organisms’ resilience to environmental stressors associated with seawater acidification. Although insights gained from this study are preliminary, mostly due to the limited number of replicates in the egg biochemical analysis, they contribute to unveiling the adaptive capabilities of sea urchins in facing ongoing ocean acidification challenges.
Continue reading ‘Adaptive resilience of sea urchins against seawater acidification: a study on egg quality and offspring performance within a volcanic vents area’Influences on chemical distribution patterns across the west Greenland shelf: the roles of ocean currents, sea ice melt, and freshwater runoff
Published 19 February 2025 Science ClosedTags: Arctic, chemistry
The west Greenland shelf is a dynamic marine environment influenced by various physicochemical and biological processes. This study provides an overview of the main factors affecting the distribution of macronutrients, carbonate system parameters, and dissolved trace elements during late summer. Key drivers include major ocean currents, melting sea ice, and terrestrial freshwater runoff, each uniquely contributing to the cycling and spatial distribution of chemical constituents. Major ocean currents, such as the southward-moving Baffin Island Current (BIC) and the northward-moving West Greenland Current (WGC), shape the chemical composition of shelf waters by introducing water masses with distinct chemical signatures. Melting sea ice is an important source of freshwater and dissolved constituents for the marine environment. The east-to-west direction of sea ice retreat creates nutrient gradients, with low nutrient levels in highly productive shelf waters and high nutrient levels in areas with prolonged ice cover. This process also affects the carbonate system, leading to changes in pH and aragonite saturation states, which is critical for the health of marine organisms. Terrestrial freshwater runoff, particularly from the Greenland Ice Sheet (GIS), replenishes macronutrients in the photic zone, stimulating primary production and creating important CO2 sinks. However, surface waters become more susceptible to acidification by the input of poorly buffered glacial freshwater. Understanding these key drivers is essential for forecasting future changes in the marine chemistry and biology of the west Greenland shelf, especially in the context of ongoing climate change within this high-latitude region.
Continue reading ‘Influences on chemical distribution patterns across the west Greenland shelf: the roles of ocean currents, sea ice melt, and freshwater runoff’Transcriptome‐to‐phenome response of larval Eastern oysters under multiple drivers of aragonite undersaturation
Published 19 February 2025 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, morphology, mortality, multiple factors, reproduction, respiration, salinity, temperature
Understanding how interactive environmental challenges affect marine species is critical to long‐term ecological and economic stability under global change. Marine calcifiers are thought to be vulnerable to ocean acidification (OA; elevated pCO2); active dissolution of aragonite (Ωar) is associated with disrupted development, survivorship, and gene expression in bivalve larvae, resulting in an early life‐stage bottleneck. Dynamic carbonate chemistry in coastal systems emphasizes the importance of multiple stressors, e.g., warming and low salinity events may change organismal responses relative to OA alone. We exposed Eastern oyster larvae ( Crassostrea virginica ) to a full‐factorial experimental design using two temperatures (23°C and 27°C), salinities (17 and 27), and pCO2 levels (~700 μatm and 1850 μatm pCO2), resulting in Ωar conditions 0.3–1.7. Ωar reduced by low salinity, elevated pCO2, and low temperature, each slowed early development and reduced survival. Low salinity × elevated pCO2 was linked to severe Ωar undersaturation (< 0.5) that suppressed expression of bicarbonate transport, biomineralization and augmented expression for ciliary locomotion, proteostasis, and histone modifiers. In isolation and under moderate Ωar intensity (0.5 < Ωar < 1), larvae increased transcription for osmoregulatory activity and endocytosis under low salinity, and suppressed transcription for iron metabolism under elevated pCO2. Although shell growth and survival were affected by Ωar undersaturation, gene expression patterns of D‐stage oyster larvae and oyster juveniles suggests tolerance to dynamic estuarine environments. Genes and expression patterns that confer survival of postmetamorphosed oysters can improve our understanding of environmental‐organismal interactions and improve breeding programs enabling sustainable production.
Continue reading ‘Transcriptome‐to‐phenome response of larval Eastern oysters under multiple drivers of aragonite undersaturation’Buoy-based monitoring of sea surface carbon dioxide partial pressure at Qingdao coastal area
Published 19 February 2025 Science ClosedTags: chemistry, field, North Pacific
Continuous time series observations of seawater carbon dioxide partial pressure (pCO2) are crucial for documenting temporal variations in air-sea CO2 fluxes. To examine the seawater pCO2 variation and its influence factors at Qingdao coastal waters, a high-resolution observation of seawater pCO2 near the Xiaomaidao Island was conducted from May 29 to July 25 in 2024. Sea surface pCO2 varied from 519 µatm to 717 µatm during this monitoring period, with an obvious decline and rise from July 12 to 21. The variation of seawater pCO2 was mainly affected by the increasing sea surface temperature, except for the period of pCO2 decrease which was caused by Ulva prolifera bloom. Accompanied by the increase of U. prolifera, sea surface pCO2 decreased to 563 µatm, then the coverage of U. prolifera decreased and sea surface pCO2 rose to 669 µatm during period of July 12 to 21. The observation site acted as a source for atmospheric CO2 throughout the monitoring period, with air-sea CO2 flux ranging from less than 1 mmol m-2 d-1 to over 100 mmol m-2 d-1, resulting in a total CO2 release of 334 mmol m-2. Thus, it is essential for high-resolution measurement of pCO2 in coastal areas.
Continue reading ‘Buoy-based monitoring of sea surface carbon dioxide partial pressure at Qingdao coastal area’CO2 hydration at the air-water interface: a surface-mediated ‘in and out’ mechanism
Published 18 February 2025 Science ClosedTags: chemistry, modeling
An understanding of the CO2 + H2O hydration reaction is crucial for modeling the effects of ocean acidification, for enabling novel carbon storage solutions, and as a model process in the geosciences. While the mechanism of this reaction has been investigated extensively in the condensed phase, its mechanism at the air-water interface remains elusive, leaving uncertain the contribution that surface-adsorbed CO2 makes to the overall acidification reaction. In this study, we employ state of-the-art machine-learned potentials to provide a molecular-level understanding of CO2 hydration at the air-water interface. We show that reaction at the interface follows a surface-mediated ‘In and Out’ mechanism: CO2 diffuses into the aqueous surface layer, reacts to form carbonic acid, and is subsequently expelled from solution. We show that this surface layer provides a bulk-like solvation environment, engendering similar modes of reactivity and near-identical free energy profiles for the bulk and interfacial processes. Our study unveils a new, unconventional reaction mechanism that underscores the dynamic nature of the molecular reaction site at the air-water interface. The similarity between bulk and interfacial profiles shows that CO2 hydration is equally as feasible under these two solvation environments and that acidification rates are likely enhanced by this additional surface contribution.
Continue reading ‘CO2 hydration at the air-water interface: a surface-mediated ‘in and out’ mechanism’Carbon dioxide–induced acidification enhances short-lived brominated hydrocarbons production in oligotrophic oceans
Published 18 February 2025 Science ClosedTags: biogeochemistry, biological response, community composition, field, Indian, multiple factors, nutrients, otherprocess, physiology, phytoplankton, South Atlantic
Oceanic emission is a primary source of brominated very short-lived substances (BrVSLs) to the atmosphere, which have important effects on stratospheric ozone chemistry. Marine biogeochemical processes regulating BrVSLs are often sensitive to ocean acidification. Yet, the response of BrVSLs production to acidification remains poorly understood. Herein, the effects of acidification on the production of two main BrVSLs, dibromomethane (CH2Br2) and tribromomethane (CHBr3), were studied by ship-based incubation experiments at three stations in the South Atlantic and Indian Oceans. The average CH2Br2 and CHBr3 concentrations increased by 17.2–58.7% and 14.3–80.3% due to acidification under the in situ nutrient conditions with nutrient and/or iron limitation at the three stations, but the mechanisms driving these increases varied among different regions. The increased bromoperoxidase (BrPO) activity caused by acidification facilitated BrVSLs release in the Eastern Tropical Indian Ocean, where diatoms were dominant. CHBr3 increased due to acidification as a result of enhanced reactivity of dissolved organic matter (DOM) in the Eastern Tropical Atlantic, where dinoflagellates were dominant. Brominated very short-lived substances increased due to acidification as a result of a combined effect of the above two mechanisms in the Benguela Current Coastal with high phytoplankton abundance. Under the nutrient and/or iron addition conditions with nutrient and iron sufficiency, however, acidification did not promote BrVSLs production due to its only minor effect on the BrPO activity and reactivity of DOM, partly because the effect of increased oxidative stress was offset by that of changed phytoplankton composition. Our study provided a basis for future modeling on the impact of acidification on global BrVSLs emissions.
Continue reading ‘Carbon dioxide–induced acidification enhances short-lived brominated hydrocarbons production in oligotrophic oceans’
