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’Posts Tagged 'reproduction'
Increasing acidification does not affect sexual reproduction of a solitary zooxanthellate coral transplanted at a carbon dioxide vent
Published 8 May 2025 Science ClosedTags: biological response, corals, field, Mediterranean, morphology, reproduction, vents
Ocean acidification research on ecologically and economically important sea cucumbers Is limited globally
Published 18 April 2025 Science ClosedTags: 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 ClosedTags: 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 pHNBS 8.1, larvae exposed at pHNBS 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 pHNBS 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.
Continue reading ‘Initiation of bivalve shell calcification under ocean acidification: integrating insights from shell to cell’Food availability, but not tidal emersion, influences the combined effects of ocean acidification and warming on oyster physiological performance
Published 25 March 2025 Science ClosedTags: 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’Physiological effects of acute exposure to acidification conditions in embryos of the American lobster (Homarus americanus)
Published 12 March 2025 Science ClosedTags: 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.
Continue reading ‘Physiological effects of acute exposure to acidification conditions in embryos of the American lobster (Homarus americanus)’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’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’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’Ocean acidification may contribute to recruitment failure for Bering Sea red king crab
Published 29 January 2025 Science ClosedTags: 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.
Continue reading ‘Ocean acidification may contribute to recruitment failure for Bering Sea red king crab’Single-larva RNA sequencing reveals that red sea urchin larvae are vulnerable to co-occurring ocean acidification and hypoxia
Published 22 January 2025 Science ClosedTags: 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’Exposure to a gradient of warming and acidification highlights physiological,molecular, and skeletal tolerance thresholds in Pocillopora acuta recruits
Published 21 January 2025 Science ClosedTags: biological response, corals, laboratory, molecular biology, morphology, mortality, multiple factors, North Pacific, reproduction, temperature
Ocean warming and acidification are among the biggest threats to the persistence of coral reefs. Organismal stress tolerance thresholds are life stage specific, can vary across levels of biological organization, and also depend on natural environmental variability. Here, we exposed the early life stages of Pocillopora acuta in Kāne‘ohe Bay, Hawai‘i, USA, a common reef-building coral throughout the Pacific, to projected ocean warming and acidification scenarios. We measured ecological, physiological, biomineralization, and molecular responses across the critical transition from larvae to newly settled recruits following 6 days of exposure to diel fluctuations in temperature and pH in Control (26.8-27.9°C, 7.82-7.96 pHTotal), Mid (28.4-29.5°C, 7.65-7.79 pHTotal) and High conditions (30.2-31.5°C, 7.44-7.59 pHTotal). We found that P. acuta early life stages are capable of survival, settlement, and calcification under all scenarios. The High conditions, however, caused a significant reduction in survival and settlement capacity, with changes in the skeletal fiber deposition patterns. In contrast to a limited impact on the expression of biomineralization genes, the dominant transcriptomic response to the High conditions relative to the two other treatments included depressed metabolism, reduced ATP production and increased activity of DNA damage-repair processes. Collectively, our findings indicate that corals living in environments with large diurnal fluctuations in seawater temperature and pH, such as Kāne‘ohe Bay, can tolerate exposure to moderate projected increased temperature and reduced pH. However, under more severe environmental conditions significant negative effects on coral cellular metabolism and overall organismal survival jeopardize species fitness and recruitment.
Continue reading ‘Exposure to a gradient of warming and acidification highlights physiological,molecular, and skeletal tolerance thresholds in Pocillopora acuta recruits’Meta-analysis of larval bivalve growth in response to ocean acidification and its application to sea scallop larval dispersal in the Mid-Atlantic Bight
Published 21 January 2025 Science ClosedTags: biological response, growth, individualmodeling, modeling, mollusks, reproduction, review
Ocean acidification, caused by increasing atmospheric carbon dioxide and coastal physical, biological, and chemical processes, is an ongoing threat to carbonate-utilizing organisms living in productive coastal shelves. Bivalves exposed to acidification have shown reduced growth, reproduction, and metabolic processes, with larval stages exhibiting the greatest susceptibility. Here, we compile results from published studies on larval bivalve growth responses to acidification to estimate a relationship between larval growth and seawater aragonite saturation state. We then apply this relationship to a larval dispersal individual-based model for Atlantic sea scallops (Placopecten magellanicus), an economically vital species in the Mid-Atlantic Bight that is historically under-studied in acidification research. To date, there have been no published studies on sea scallop larval response to ocean acidification. Model simulations allowed the identification of potential impacts of acidification on scallop success in the region. Results show that larval sea scallops that are sensitive to ocean acidification had a 17% lower settlement success rate and over 50% reduction in larval passage between major Mid Atlantic Bight fisheries habitats than those that are not sensitive to acidification. Additionally, temperature and ocean acidification interact as drivers of larval success, with aragonite saturation states > 3.0 compensating for temperature-induced mortality (> 19 ˚C) in some cases. This balance between drivers influences larval settlement success across spatial and interannual scales in the Mid Atlantic Bight.
Continue reading ‘Meta-analysis of larval bivalve growth in response to ocean acidification and its application to sea scallop larval dispersal in the Mid-Atlantic Bight’Effects of sediment acidification on germinability of Scrippsiella acuminata cysts in hypoxic zones
Published 16 January 2025 Science ClosedTags: biological response, field, laboratory, morphology, North Pacific, phytoplankton, reproduction, sediment
We investigated the calcareous cysts of Scrippsiella acuminata, with a focus on morphological changes from spiny to naked types in the surface sediments of hypoxic zones. The cyst-type abundance and bottom environmental conditions at two stations, representing hypoxic and normoxic conditions, were compared. Germination tests simulating in situ pH conditions were conducted to elucidate differences in germinability between spiny and naked cysts. The pH values at the hypoxic station reached a minimum of 7.2 in September, coinciding with high bottom-water temperatures and low dissolved oxygen levels. Significant differences in cyst abundance were observed; naked and intermediate cysts dominated the hypoxic station, whereas spiny cysts were more abundant at the normoxic station. Both cyst types exhibited a similar negative effect of germinability decrease (62 to 25% for spiny cysts and 75 to 32% for naked cysts) in acidic conditions (7.2) compared to normal pH conditions (7.7). Morphological changes in ungerminated cysts, such as cytoplasmic degradation and wall thickening, occurred under acidified conditions.
Continue reading ‘Effects of sediment acidification on germinability of Scrippsiella acuminata cysts in hypoxic zones’Molecular response to CO2-driven ocean acidification in the larvae of the sea urchin Hemicentrotus pulcherrimus: evidence from comparative transcriptome analyses
Published 13 January 2025 Science ClosedTags: biological response, echinoderms, laboratory, molecular biology, morphology, North Pacific, reproduction
Highlights
- Ocean acidification affects morphology of Hemicentrotus pulcherrimus larvae.
- Comparative transcriptome analyses were performed.
- Six key potential biomarkers correlated with low pH tolerance were identified.
Abstract
In order to explore the impact of CO2-driven ocean acidification (OA) on gene expression of sea urchins, gametes of Hemicentrotus pulcherrimus were fertilized and developed to the four-armed larvae in either seawater at current pH levels (pHNBS = 7.98) or in three laboratory-controlled OA conditions (ΔpHNBS = −0.3, −0.4, −0.5 units) based on the projections of the Intergovernmental Panel on Climate Change (IPCC) for 2100. Four-armed larval specimens were collected, and comparative transcriptome analysis was then performed. The results showed that 58 differentially expressed genes (DEGs) were identified in OA-treated groups as compared to the control. Moreover, more transition and transversion SNPs were observed in OA-treated groups than those in the control indicating a potential occurrence of adaption to OA in H. pulcherrimus larvae. Six candidate DEGs shared among OA-treated groups were identified as potential biomarkers correlated with low pH tolerance, mainly enriched in nine pathways associated with Notch signaling, dorso-ventral axis formation, oxidative phosphorylation, lysine degradation, valine, leucine and isoleucine degradation, lysosome, cell adhesion molecules, glutathione metabolism and PPAR signaling pathway. These results will not only enrich our knowledge of the impacts of OA on sea urchin larvae from the aspect of gene expression, provide a better understanding on larval forms coping with OA, but also offer more clues and biomarkers for developing protection or management strategies for sea urchins under near-future OA conditions.
Continue reading ‘Molecular response to CO2-driven ocean acidification in the larvae of the sea urchin Hemicentrotus pulcherrimus: evidence from comparative transcriptome analyses’Dynamic responses during early development of the sea urchin Strongylocentrotus intermedius to CO2-driven ocean acidification: a microRNA-mRNA integrated analysis
Published 9 January 2025 Science ClosedTags: biological response, echinoderms, laboratory, molecular biology, reproduction
Highlights
- Sea urchin blastula stage is the most sensitive stage to ocean acidification (OA).
- The PI3K/Akt pathway may be a hub pathway responding to OA in sea urchin larvae.
- MiR-1 may be a key regulator in the dynamic response of sea urchin larvae to OA.
Abstract
To explore the dynamic molecular responses to CO2-driven ocean acidification (OA) during the early developmental stages of sea urchins, gametes of Strongylocentrotus intermedius were fertilized and developed to the four-armed larva stage in either natural seawater (as a control; pHNBS = 7.99 ± 0.01) or acidified conditions (ΔpHNBS = −0.3, −0.4, and − 0.5 units) according to the prediction for ocean pH by the end of this century. Specimens from five developmental stages (fertilization, cleavage, blastula, prism, and four-armed larva) were collected and comparative microRNA (miRNA) and mRNA transcriptome analyses were performed. The results showed that 1) a total of 22,224 differentially expressed genes (DEGs) and 51 differentially expressed miRNAs (DEMs) were identified in the OA-treated groups compared with the control group. 2) The numbers of both DEGs and DEMs were the largest at the blastula stage, indicating dramatic changes in gene expression. 3) Five “miR-1/DEG” modules were identified as potential biomarkers reflecting the response of sea urchins to OA during the early developmental period. 4) The PI3K/Akt signaling pathway was a key pathway involved in the response of S. intermedius to OA in its early developmental stages. This study deepens our understanding of the dynamic molecular regulatory mechanisms underlying sea urchin responses to CO2-driven OA.
Continue reading ‘Dynamic responses during early development of the sea urchin Strongylocentrotus intermedius to CO2-driven ocean acidification: a microRNA-mRNA integrated analysis’Low pH means more female offspring: a multigenerational plasticity in the sex ratio of marine bivalves
Published 7 January 2025 Science ClosedTags: biological response, field, laboratory, molecular biology, mollusks, North Pacific, reproduction
Global changes can profoundly affect the sex determination and reproductive output of marine organisms, disrupting the population structure and ecosystems. High CO2-driven low pH in the context of ocean acidification (OA) has been shown to severely affect various calcifiers, but less is known about the extent to which low pH influences sex determination and reproduction of marine organisms, particularly mollusks. This study is the first to report a biased sex ratio over multiple generations toward females, driven by exposure to high CO2-induced low pH environments, using the ecologically and economically important Portuguese oyster (Crassostrea angulata) as a model. This phenomenon, which we term pH-mediated sex determination (PSD), has no consequences for fecundity, gonadal development, or reproductive function in the offspring. Moreover, PSD persisted into a second year of reproduction and was inherited across multiple generations. Transcriptomic analysis indicates PSD is associated with the activation of the Wnt signaling pathway in females and inhibition of spermiogenesis-related functions in males. This work expands our understanding of environmental sex determination and highlights the possible impact of global changes on reproduction and population dynamics of mollusks and other marine organisms.
Continue reading ‘Low pH means more female offspring: a multigenerational plasticity in the sex ratio of marine bivalves’Characterization of coral communities in the shallow hydrothermal vents of Mabini, Batangas, Philippines
Published 31 December 2024 Science ClosedTags: algae, biological response, BRcommunity, chemistry, community composition, corals, field, growth, North Pacific, reproduction, vents
The existence of shallow hydrothermal vents in Mabini, Batangas, Philippines, has been recognized to contribute to CO2-rich submarine groundwater discharges. However, little is known about the existing coral community structure in the area which provides valuable ecosystem goods and ecological services. We characterized the reef community in this unique microenvironment falls within the predicted future reef condition with low pH and aragonite saturation using coral recruitment tiles, examined coral life-history strategies and size frequency distribution, and measured calcification of transplanted fragments from the genus Goniopora sp., Pectinia sp., and Porites sp. The availability of larval supply has proven that corals can still settle (45–73 recruits m−2) due to the presence of hard substrate and settlement cues such as the crustose coralline algae. The existing coral colonies were mostly dominated by stress-tolerant groups and sizes ranging from 5 to 20 cm. Deployed coral fragments showed growth via extension, and calcification was negatively affected by local conditions, such as Porites sp. fragments. Higher nutrient input may have promoted coral growth, but combined with low carbonate chemistry, it likely made the corals more susceptible to physical damage, as seen on the fragments. This study highlights the importance of naturally occurring extreme environments to determine climate-resilient corals that can adapt to changing conditions and recover from disturbances over time.
Continue reading ‘Characterization of coral communities in the shallow hydrothermal vents of Mabini, Batangas, Philippines’Will climate change alter the swimming behavior of larval stone crabs?: a guided-inquiry lesson
Published 23 December 2024 Science ClosedTags: biological response, crustaceans, education, multiple factors, performance, reproduction, temperature
The ocean has absorbed ~one third of the excess atmospheric carbon dioxide (CO2) released since the Industrial Revolution. When the ocean absorbs excess CO2, a series of chemical reactions occur that result in a reduction in seawater pH, a process called ocean acidification. The excess atmospheric CO2 is also resulting in warmer seawater temperatures. These stressors pose a threat to marine organisms, especially during earlier life stages (i.e., larvae). The larvae of species like the Florida stone crab (Menippe mercenaria) are free swimming, allowing a population to disperse and recruit into new habitats. After release, stone crab larvae undergo vertical swimming excursions in response to abiotic stimuli (gravity, light, pressure) allowing them to control their depth. Typically, newly hatched larvae respond to abiotic cues that would promote a shallower depth distribution, where surface currents can transport them offshore to complete development. As larvae develop offshore, they become less sensitive to certain abiotic stimuli, which promotes a deeper depth distribution that may expose them to variable current speeds, thus influencing the direction of advection (horizontal movement). Environmental stressors like ocean acidification and elevated seawater temperatures may also impact the larvae’s natural response to these abiotic stimuli throughout ontogeny (development). Changes in their natural swimming behavior due to climate stressors could, therefore, influence the transport and dispersal of the species. This guided-inquiry lesson challenges introductory marine biology and oceanography students to determine how future ocean pH and temperature projections could impact the swimming behavior of Florida stone crab larvae.
Continue reading ‘Will climate change alter the swimming behavior of larval stone crabs?: a guided-inquiry lesson’
