reproduction Archives - Page 6 of 53

Posts Tagged 'reproduction'

Impacts of ocean acidification and altered prey fatty acids on the early development of northern rock sole (Lepidopsetta polyxystra) larvae

Published 3 July 2025 Science Closed
Tags: biological response, fish, laboratory, morphology, mortality, multiple factors, North Pacific, physiology, reproduction

Highlights

Carbon dioxide (CO₂) and dietary fatty acids (FAs) had stage-specific effects on northern rock sole larvae.
After 2-weeks of feeding, larvae had faster growth under elevated CO₂ conditions.
After 5-weeks of feeding, larvae had higher lipid storage when fed a diet with balanced-essential FAs.

Abstract

Ocean acidification (OA) is predicted to affect the physiological rates of larval fish and invertebrates and is also expected to significantly impact marine fisheries through alteration of food webs. We examined whether mortality rates, body size, and condition of first-feeding larval northern rock sole, Lepidopsetta polyxystra, were synergistically influenced by prey quality (essential fatty acids, EFAs) and high carbon dioxide (CO₂) exposure. Larvae were exposed to ambient and high CO₂ levels (∼ 330 vs. 1020 μatm) and were fed diets with balanced or unbalanced EFA ratios for 7 weeks immediately following hatch. After 2 weeks, significant effects from CO₂ and diet were observed, with the largest larvae occurring in the high CO₂ exposure group that received a balanced EFA diet. After 5 weeks of exposure, the effects of elevated CO₂ had a diminished impact on larval size, but larvae reared on the balanced EFA diet maintained higher lipid-based condition metrics than those fed an unbalanced EFA diet. Survival was variable across replicate tanks and not significantly different between treatments. This study suggests that L. polyxystra larvae are most vulnerable to OA and food web change at different points in their development. Further understanding of these ecosystem effects will be required to predict the impacts of OA on northern rock sole fisheries.

Continue reading ‘Impacts of ocean acidification and altered prey fatty acids on the early development of northern rock sole (Lepidopsetta polyxystra) larvae’

Ocean acidity extremes retard shell formation of bivalve larvae: insights from transcriptomics and lipidomics

Published 2 July 2025 Science Closed
Tags: biological response, laboratory, molecular biology, mollusks, morphology, North Pacific, physiology, reproduction

Highlights

Effects of ocean acidity extremes (OAX) on early development of clams were assessed.
OAX retarded shell formation of clam larvae.
Reduced Ca²⁺ uptake and HCO₃⁻ production led to larval developmental retardation.
OAX decreased cell membrane fluidity, limiting the uptake of calcification substrates.
Larval shell formation under OAX was inhibited by depletion of energy reserves.

Abstract

In view of climate change and human activities, ocean acidity extreme (OAX) events have been increasingly reported worldwide over the last decades, which possibly retard the growth and development of marine organisms, particularly at their early life-history stages (e.g., embryos or larvae). Thus, understanding whether they can adjust to the sudden increase in seawater acidity has drawn growing attention. Using a commercially and ecologically important bivalve species (Ruditapes philippinarum) with a widespread distribution in the world, we assessed the impact of OAX on its embryonic and larval development as well as expressions of functional genes and lipids to indicate physiological and cellular performance. We found that embryonic development and larval shell formation were inhibited by OAX mainly due to the downregulation of key genes responsible for the uptake of calcium ions from ambient seawater (e.g., NCX, VGCC and SERCA) and the reduced production of bicarbonate ions through the catalytic action of carbonic anhydrase. In addition, a major remodelling in membrane lipids (e.g., PC, PE, PG, PI and PS) indicated that OAX impacted the fluidity and stability of cell membrane, hindering the uptake of calcification substrates. The depletion in energy reserves, such as triacylglycerol, can also account for the impairment in larval shell formation under OAX conditions. By integrating transcriptomics and lipidomics, our findings illustrate a novel molecular mechanism underlying the detrimental effect of OAX on larval development and hence population maintenance of marine organisms, which can have profound implications for sustaining ecosystem stability and aquaculture management.

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Developmental and transgenerational effects of climate change on inorganic mercury toxicity in a marine copepod

Published 25 June 2025 Science Closed
Tags: biological response, crustaceans, laboratory, molecular biology, multiple factors, North Pacific, oxygen, physiology, reproduction, zooplankton

Highlights

Offspring/persistent OA plus OW aggravated IHg toxicity in T. japonicus.
Persistent OA had stronger mitigating effect on IHg toxicity than offspring OA.
OA plus OW intensified IHg toxicity in copepods mainly via lysosome dysfunction.
Persistent OA enhanced energy metabolism and Hg efflux, decreasing IHg toxicity.
Different scenarios of climate change can variably affect IHg toxicity in copepods.

Abstract

Dynamic shifts in multiple stressors are frequent in the marine environment. Here, we conducted a multigenerational experiment (F1-F4) to explore how different temporal scenarios of climate change, i.e., offspring/persistent ocean acidification (OA), warming (OW), and their combination (AW), could affect inorganic mercury (IHg) toxicity in the marine copepod Tigriopus japonicus. We found that persistent OA exhibited stronger mitigating effect on IHg toxicity in copepods than offspring OA, while offspring/persistent OW and AW aggravated its toxicity effects. We specifically performed transcriptomic analysis for the copepods of F4. Our transcriptomic result showed energy metabolism and detoxification were activated by persistent OA, enabling the copepods to resist IHg exposure. Instead, detoxification- and reproduction-related processes were inhibited in IHg-treated copepods under offspring/persistent OW and AW scenarios. Although apoptosis was suppressed to probably protect IHg-treated copepods under persistent AW, oxidative stress and lysosomal dysfunction ultimately caused reproductive impairment. Our study highlights that offspring/persistent (i.e., developmental/transgenerational) OA and OW could differentially modulate Hg toxicity in marine copepods, and more studies should focus on the temporal variation and complex interaction of multiple stressors, helping accurately project marine biota’s response in the future ocean.

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Population and maternal variation in the sensitivity of Dungeness crab Metacarcinus magister zoeae to elevated CO2

Published 10 June 2025 Science Closed
Tags: adaptation, biological response, crustaceans, laboratory, morphology, mortality, North Pacific, otherprocess, reproduction

The response of marine organisms to ocean acidification depends on their adaptive capacity, which can be partially understood by evaluating the amount of existing variability in CO₂ sensitivity within a species. The process of local adaptation is a mechanism that can drive variability in CO₂ sensitivity. In this study, we measured the survival and molt rate of Dungeness crab Metacarcinus magister zoeae that were produced by gravid crabs collected from 3 locations in waters off of Washington State, USA, and reared in a common laboratory in ambient, medium, and high CO₂ treatments. The 3 locations from which crabs were collected have different carbonate chemistry dynamics, and Dungeness crabs in these locations are to some extent genetically distinct. We hypothesized that these conditions may favor local adaptation. We did not find evidence of local adaptation, but did see different levels of CO₂ sensitivity associated with the mother. This variation in CO₂ sensitivity suggests an adaptive capacity that is likely to influence Dungeness crab response to future acidification.

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Effects of ocean warming and acidification on the embryonic development of Doryteuthis opalescens and Doryteuthis pealeii

Published 9 June 2025 Science Closed
Tags: biological response, mollusks, morphology, multiple factors, North Pacific, physiology, reproduction, temperature

Projected increases in ocean temperature and partial pressure of carbon dioxide (pCO₂) due to anthropogenic carbon emissions are expected to significantly alter coastal marine ecosystems, particularly within the Southern California Bight and Northwest Atlantic Ecoregion. These changes may disrupt food web stability through alterations in abiotic conditions. To assess the impacts of elevated temperature and pCO₂ on embryonic development in the superorder Decapodiformes, I investigated two mid-trophic squid species, Doryteuthis opalescens and Doryteuthis pealeii, during their paralarval stage. Specifically, I examined metabolic and morphological responses in squid reared in four seawater treatments: combinations of present-day and projected levels of temperature and pCO₂ by the end of the century. The results revealed species-specific responses. D. opalescens paralarvae exhibited generally negative responses, including reduced morphological development, under elevated temperature and pCO₂ conditions. In contrast, D. pealeii paralarvae demonstrated positive responses, with increased morphological dimensions under the same conditions. Additionally, D. pealeii paralarvae showed elevated O₂ consumption rates, while D. opalescens paralarvae exhibited a more subdued metabolic response to temperature increases. These findings highlight significant interspecific variability in responses to future ocean conditions, despite the similarity in life history traits between the two species. This study underscores the complexity of climate change impacts on Decapodiformes and emphasizes the necessity of species-specific assessments to predict ecological consequences for marine organisms.

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Positive interactions in a warmer and more acidic ocean: crustose coralline algae holobionts enhance gorgonian larval settlement under climate change

Published 21 May 2025 Science Closed
Tags: algae, biological response, BRcommunity, corals, laboratory, Mediterranean, molecular biology, multiple factors, physiology, prokaryotes, reproduction, temperature

Background: The increasing frequency of marine heatwaves is leading to mass mortality of gorgonians in the Mediterranean Sea, threatening some populations with local extinction. A better understanding of the dynamics of gorgonians’ early life stages under climate change is urgent to ensure their conservation. Crustose coralline algae (CCAs) and their associated bacteria are known to induce the larval settlement of several coral species through the production of chemical cues. The larvae of the white gorgonian Eunicella singularis have been observed to preferentially settle and metamorphose on CCAs. Here, we investigated this positive interaction, and explored how it might be altered by climate change. Specifically, we tested the capacity of two Mediterranean CCA holobionts, Macroblastum dendrospermum and Lithophyllum stictiforme, to foster E. singularis larval settlement after exposure to SSP5-8.5 projected conditions for 2100 (warming and acidification), combined or not with a simulated marine heatwave event.

Results: Our results showed a threefold increase of larval settlement in presence of the CCAs previously exposed to acidification and warming treatments. After these treatments, both CCAs hosted a consistently high abundance of bacteria belonging to the Pirellulaceae family, and exhibited a higher abundance of monosaccharides in their exudates. We hypothesize that the enhanced larval settlement was driven by the bacterial breakdown and utilization of CCA polysaccharides, in combination with their release through the CCA cell walls. This release may have been enhanced by a decalcification process induced by climate change conditions. Furthermore, we showed that CCAs act as sources of bacterial taxa that can establish and persist in adult E. singularis holobiont, independently of climate change effects.

Conclusions: Our results highlight that CCA-larvae interaction is critical for E. singularis recruitment success, especially under future climatic conditions, and influences the development of its microbiome. This research underscores the importance of studying positive interspecific interactions across biological levels (from microorganisms to macroorganisms) under climate change scenarios, and provides valuable insights that inform the conservation and restoration of the Mediterranean white gorgonian.

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Exposure of larval pinto abalone to ocean acidification and warming negatively impacts survival, settlement, and size

Published 13 May 2025 Science Closed
Tags: biological response, laboratory, mollusks, morphology, mortality, multiple factors, North Pacific, reproduction, temperature

Pinto abalone (Haliotis kamtschatkana), the only abalone species native to Washington, declined by 97% in the state from 1992 to 2017. Their decline is a loss for indigenous tribes, recreational divers, and the health of subtidal rocky reefs and kelp beds. Current restoration actions are facing threats of ocean acidification and warming in the northeast Pacific. This research aims to deepen our understanding of the tolerance and physiological flexibility of early life history stages of pinto abalone and inform hatchery practices under future climate change scenarios. We conducted an experiment to test how seawater pH and temperature stress impact abalone larvae. We exposed abalone post-fertilization to elevated temperature and reduced seawater pH for ten days spanning their larval development period: (1) 7.95pH/14°C (ambient), (2) 7.60pH/14°C, (3) 7.95pH/18°C, and (4) 7.60pH/18°C. Abalone in the ambient treatment had the best survival, those in the 7.60pH/18°C treatment had the worst survival, and those in the two single-stressor treatments had survival in between. Among the surviving larvae, pH was the dominant stressor influencing settlement success, with higher settlement rates under ambient pH treatments at both temperatures. pH also had a stronger effect than temperature on shell length. The information gleaned from this study is essential for optimizing future restoration aquaculture for pinto abalone and determining their ideal habitat and potential geographic range.

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Examining behavioral alterations in zebrafish (Danio rerio) larvae in the context of anthropogenic climate change

Published 9 May 2025 Science Closed
Tags: biological response, fish, laboratory, multiple factors, performance, reproduction, temperature

Behavioral responses induced by climate change in fish have received increased attention in recent years. Near future projected CO₂ levels (420 µatm to 1000 µatm) and increased temperature (~4 °C) expected in ocean and freshwater basins by 2100 have been shown to impair various behaviors such as locomotor activity and learning in early life stage fish. Despite widespread characterization, we know little about why these disruptions occur and how compounded effects of climate change might disrupt behavioral paradigms. Using the biomedical research model, the zebrafish (Danio rerio), a species with a well-documented behavioral repertoire and broadly utilized for mapping neural activity linked to behavior, this study aimed to assess how elevated CO₂ and temperature may affect behavior during early development. Larvae 6-7 days post fertilization were acclimated to either control (420 µatm CO₂; 28 °C) or 1,000 µatm pCO₂ and temperatures of 32 °C combined or singly before being subjected to various behavioral assays, consisting of acoustic- and visual stimuli to examine startle responses and their habituation. The results suggest that temperature more than CO₂ significantly altered the startle response, and to some extent, the habituation of this response. Both acoustic- and visual startle response were negatively affected by climate change relevant heat-exposure, while aquatic acidification had no significant effect on the acoustic startle response singly. Conversely, habituation appears to have increased under elevated temperature treatment in isolation compared to ambient levels. This experiment may help highlight zebrafish’s potential as a model organism for further climate- behavioral and physiological investigations, supported by their advanced gene editing and transgenic tools, optical transparency, and compatibility with high-throughput screening approaches.

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Increasing acidification does not affect sexual reproduction of a solitary zooxanthellate coral transplanted at a carbon dioxide vent

Published 8 May 2025 Science Closed
Tags: biological response, corals, field, Mediterranean, morphology, reproduction, vents

The absorption of atmospheric carbon dioxide is causing significant changes to the carbonate chemistry of the ocean, in a phenomenon called ocean acidification. The latter makes it potentially more difficult for marine calcifiers like corals, to build their calcium carbonate structures, thus affecting their ability to survive and reproduce. Research on how ocean acidification impacts coral sexual reproduction has focused on tropical species investigated under controlled conditions in aquaria, lacking insights into the intricate natural environment. Here we show that the sexual reproduction of the zooxanthellate solitary scleractinian Balanophyllia europaea transplanted at a CO2 vent off the Island of Panarea (Tyrrhenian Sea, Italy) for up to 5 months is unaffected by decreasing pH (pH range 8.1–7.4). These findings reinforce earlier evidence, suggesting that zooxanthellate corals may exhibit a certain degree of short-term resilience to ocean acidification. However, the interplay between ocean acidification and additional environmental stressors, including warming, will ultimately define the boundaries that distinguish winners and losers amid swift climatic changes.

Continue reading ‘Increasing acidification does not affect sexual reproduction of a solitary zooxanthellate coral transplanted at a carbon dioxide vent’

Ocean acidification research on ecologically and economically important sea cucumbers Is limited globally

Published 18 April 2025 Science Closed
Tags: biological response, echinoderms, physiology, reproduction, review

Ocean acidification (OA) caused by increasing levels of partial pressure of carbon dioxide (CO₂) and subsequent changes in seawater carbonate chemistry exerts knock-on effects on various calcifying organisms. However, little is known about the echinoderms (e.g., sea cucumbers) that are being overexploited globally for economic benefits. Most importantly, less is known about the impacts of OA on these organisms. Within this framework, the current study synthesized the available global data on the effects of OA on various sea cucumber species. Results indicate studies on OA impacts on sea cucumbers are limited to 10 species across eight countries globally, with Apostichopus japonicus being highly utilized under experimental conditions. Our results suggest that OA impacts reproduction, spawning events and sperm flagellar motility of sea cucumbers under low pH. This leads to the loss of energy allocations and reduction in somatic growth. Under low pH, the effects on Ca2+ and Mg2+ composition of calcareous ring and ossicles were species-specific and enzymatic activity was reduced. This study highlights the existing gaps that need to be addressed to prevent various knock-on effects of OA on sea cucumbers. This information is critical to managers and conservationists to manage the globally declining sea cucumber populations.

Continue reading ‘Ocean acidification research on ecologically and economically important sea cucumbers Is limited globally’

Initiation of bivalve shell calcification under ocean acidification: integrating insights from shell to cell

Published 9 April 2025 Science Closed
Tags: biological response, laboratory, molecular biology, mollusks, morphology, North Pacific, physiology, reproduction

The formation of initial bivalve shell is sensitive to ocean acidification, encoding the basis of shell formation and environmental information. Here, we demonstrated how the initial shell building processes were affected under various acidified conditions. With decreasing pH, larvae showed smaller shells and higher incidences of deformity. Shell elemental and isotopic profiles suggested that larvae almost exclusively used seawater dissolved inorganic carbon to calcify and exhibited diminished ability to maintain the calcifying fluid homeostasis. Compared to those reared at pH_NBS 8.1, larvae exposed at pH_NBS 7.7 downregulated the expression of genes related to transport of calcification substrates and regulation of carbonate chemistry, all of which were subsequently upregulated at pH_NBS 7.4. This integrated finding advances the application of sclerochronology by providing insights into the initial shell formation, a crucial phase that is overlooked in sclerochronological studies, particularly in how environmental stressors affect the interpretation of geochemical proxies in adult shells.

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Food availability, but not tidal emersion, influences the combined effects of ocean acidification and warming on oyster physiological performance

Published 25 March 2025 Science Closed
Tags: biological response, growth, laboratory, mollusks, multiple factors, North Atlantic, physiology, reproduction, respiration, temperature

Highlights

Effects of pH/temperature conditions, tidal treatments, and food levels are studied.
Ocean acidification and warming enhance the physiological performance of oysters.
Food level impacts responses to future conditions and disease susceptibility.
Intertidal oysters increase food intake to compensate for limits during emersion.

Abstract

Many studies on the effects of ocean acidification and warming (OAW) in intertidal mollusks overlook critical factors like tidal emersion and food availability, both of which can shape organisms’ responses. Experiments on intertidal bivalves often use constant immersion and abundant food, which likely underestimate global change impacts and underscore the need for more realistic experiments mimicking natural ecosystems. This study investigated the physiological responses of juvenile Pacific oyster Crassostrea gigas exposed for 81 days to current and OAW conditions (+3 °C, −0.3 pH units) under two tidal treatments (0 vs. 30 % emersion) and two food levels (ad libitum vs. limited). We measured growth, reproduction, food ingestion, respiration, and biochemical traits like energy reserves and membrane fatty acids. At the experiment’s end, oysters were challenged with a viral disease to assess the physiological cost of acclimation and potential trade-offs. Results showed improved oyster physiological performance under OAW with high food level. Nevertheless, food availability emerged as the predominant factor in oyster performance, limiting growth, reproduction, and energy reserves, while increasing oxygen consumption and disease susceptibility. Food deprivation attenuated the beneficial effects of OAW through antagonistic interaction, suggesting physiologically weakened oysters may struggle to adapt to environmental hazards. Finally, tidal treatment had no significant effect, implying that oysters possess physiological compensatory mechanisms, particularly in food acquisition, enabling them to meet nutritional needs during immersion periods. This study provides valuable insights for designing global climate change experiments that align with ecological realism and improves our understanding of the acclimation potential in bivalves facing rapid ocean changes.

Continue reading ‘Food availability, but not tidal emersion, influences the combined effects of ocean acidification and warming on oyster physiological performance’

Combined effects of ocean acidification and copper exposure on the polyps of moon jellyfish Aurelia coerulea

Published 24 March 2025 Science Closed
Tags: biological response, cnidaria, laboratory, metals, morphology, multiple factors, performance, physiology, reproduction, respiration

Ocean acidification (OA) can interact with Copper (Cu) pollutants and threaten marine organisms and ecosystems. In this study, we assessed the effects of OA and Cu²⁺, alone and in combination, on the polyps of Aurelia coerulea, a common jellyfish renowned for its complex life cycle and frequent global blooms. The results revealed that ocean acidification and Cu²⁺ exposure significantly inhibited the activities of catalase, Ca²⁺-ATPase, acid phosphatase, and alkaline phosphatase in polyps, resulting in antioxidative stress effects and a significant increase in respiratory metabolism. In addition, the combination of ocean acidification and Cu²⁺ exposure caused severe tissue damage to polyps, thereby impeding their predation behavior and reducing their asexual reproduction rates. These two environmental stressors showed synergistic effects on the Ca²⁺-ATPase activity, predation rate, reproduction rate, and injury index of polyps. Therefore, reduced seawater pH and copper contamination adversely affect the physiology, growth, and development of A. coerulea polyps, which may affect the survival and population dynamics of wild populations.

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Physiological effects of acute exposure to acidification conditions in embryos of the American lobster (Homarus americanus)

Published 12 March 2025 Science Closed
Tags: biological response, crustaceans, laboratory, North Atlantic, physiology, reproduction

Highlights

Protein carbonyl concentration increased, and Na⁺/K⁺-ATPase activity decreased with decreasing acute pH in American lobster embryos.
Oxygen consumption rate and antioxidant content of embryos increased significantly over development.
American lobster embryos were sensitive to acute pH reductions representative of future ocean and coastal acidification.

Abstract

Ocean and coastal acidification are altering carbonate chemistry conditions and inducing physiological stress in marine organisms. Early life history stages of marine invertebrates, including commercially important species like the American lobster (Homarus americanus) may have limited physiological capacity to tolerate changes in carbonate chemistry. Using American lobster embryos, we quantified physiological disturbances caused by acute changes in carbonate chemistry. We exposed freshly isolated lobster embryos to conditions ranging from 6.94 to 8.07 pH for 24 h at three points during embryo development. With more extreme conditions of acidification, protein carbonyl concentration (indicative of cellular damage from oxidative stress) increased, and Na⁺/K⁺-ATPase activity (associated with acid-base regulation) decreased at all stages of development examined. Although oxygen consumption rate and ferric-reducing antioxidant potential both increased over the course of embryogenesis, we found no evidence that the relationship between pH and these physiological metrics varied during ontogeny. Our results indicate that acid-base regulation and oxidative stress in American lobster embryos may be sensitive to acidification-induced hypercapnia within a 24-h period across a large portion of embryo development.

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Metabolomic and phenotypic effects of ocean acidification on cuttlefish differ across early life stages

Published 24 February 2025 Science Closed
Tags: 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 (pH_T 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’

Transcriptome and lipidome integration unveils key mechanisms constraining bivalve larval sensitivity in an acidifying sea

Published 21 February 2025 Science Closed
Tags: 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.

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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 Closed
Tags: 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.

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Transcriptome‐to‐phenome response of larval Eastern oysters under multiple drivers of aragonite undersaturation

Published 19 February 2025 Science Closed
Tags: 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.

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Ocean acidification may contribute to recruitment failure for Bering Sea red king crab

Published 29 January 2025 Science Closed
Tags: biological response, crustaceans, fisheries, individualmodeling, modeling, North Pacific, reproduction

We used semi-parametric Bayesian regression to determine whether ocean acidification or climate warming could explain declining productivity for southeast Bering Sea red king crab (Paralithodes camtchaticus). Negative effects of acidification explained ~21% of recruitment variability over 1980-2023, and ~45% since 2000. Ocean warming had a negligible effect in our analysis. Model-estimated annual mean bottom pH in the region has fallen from ~8.03 in 1980 to ~7.89 in 2023, approaching levels that reduce juvenile survival in laboratory studies. Improved model validation and better understanding of potential threshold effects on red king crab are needed to better understand the possible population-level acidification effect that we demonstrate.

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Single-larva RNA sequencing reveals that red sea urchin larvae are vulnerable to co-occurring ocean acidification and hypoxia

Published 22 January 2025 Science Closed
Tags: biological response, dissolution, echinoderms, fisheries, molecular biology, multiple factors, North Pacific, oxygen, physiology, reproduction

Anthropogenic carbon dioxide emissions have been increasing rapidly in recent years, driving pH and oxygen levels to record low concentrations in the oceans. Eastern boundary upwelling systems such as the California Current System (CCS) experience exacerbated ocean acidification and hypoxia (OAH) due to the physical and chemical properties of the transported deeper waters. Research efforts have significantly increased in recent years to investigate the deleterious effects of climate change on marine species, but have not focused on the impacts of simultaneous OAH stressor exposure. Additionally, few studies have explored the physiological impacts of these environmental stressors on the earliest life stages, which are more vulnerable and represent natural population bottlenecks in organismal life cycles. The physiological response of the ecologically and commercially important red sea urchin (Mesocentrotus franciscanus) was assessed by exposing larvae to a variety of OAH conditions, mimicking the range of ecologically relevant conditions encountered currently and in the near future along the CCS. Skeleton dissolution, larval development, and gene expression show a response with clearly delineated thresholds that were related to OAH severity. Skeletal dissolution and the induction of Acid-sensing Ion Channel 1A at pH 7.94/5.70 DO mg/L provide particularly sensitive markers of OAH, with dramatic shifts in larval morphology and gene expression detected at the pH/DO transition of 7.71/3.71–7.27/2.72 mg/L. Experimental simulations that describe physiological thresholds and establish molecular markers of OAH exposure will provide fishery management with the tools to predict patterns of larval recruitment and forecast population dynamics.

Continue reading ‘Single-larva RNA sequencing reveals that red sea urchin larvae are vulnerable to co-occurring ocean acidification and hypoxia’

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