Carbon dioxide capture and storage (CCS) is a technology that can be used to reduce carbon dioxide (CO2) emissions generated by both natural and anthropogenic industrial processes, particularly petroleum production. To mimic and investigate the effects of CO2 leakage that may result from CCS, the acute toxicity of seawater acidification induced by continuous CO2 injection was studied in Asian seabass (Lates calcarifer) fry under static bioassay conditions. Fry (0.828 ± 0.22 g) were exposed to seawater with different pH levels (5.5, 6.0, 6.5, 7.5, and 8.3). Rapid and 100% mortality within 15 min was observed in the pH 5.5 exposure group, while mortality rates ranging from 10.00–41.67% were recorded at 6–96 h in the pH 6.0 exposure group; no mortality was noted in the other pH exposure groups. According to these mortality data, the median lethal concentration at 96 h (96 h LC50) was determined to be a pH of 5.884. Interestingly, after exposure to seawater with pH levels of 5.5 and 6.0, histopathological alterations in the skin, gills, trunk kidney and liver were evident. Additionally, some water quality parameters, especially dissolved oxygen (DO) levels, alkalinity, ammonia levels, and nitrite levels, vary depending on the pH. To further investigate the effects of seawater with pH levels of 8.3 and 5.884 (96 h LC50) and 6.5 (10% safety level) on health status, immune responses and disease susceptibility, fingerling fish (21.25 ± 3.89 g) were studied. Unexpectedly, fish exposed to seawater with a pH of 5.884 rapidly lost muscle control and gradually died, reaching 100% mortality within 24 h, and all response analyses were aborted. Interestingly, with the exception of hematocrit and some immune parameters, various serum innate immune indices, blood biochemistry parameters and immune-related gene expression patterns were similar in fish exposed to seawater with pH levels of 8.3 and 6.5. Additionally, fish were challenged with 0 (control), 1 × 107 and 1 × 109 CFU/mL Vibrio vulnificus, and fish in seawater with a pH level of 6.5 showed a higher sensitivity to 1 × 109 CFU/mL Vibrio vulnificus than fish in seawater with a pH level of 8.3, with mortality rates of 71.24% and 25.44%, respectively (p < 0.05). These findings enhance the understanding of the toxicity effects of seawater acidification caused by CO2, which will be useful for further assessing the site-specific effects of CCS projects.
Continue reading ‘Acute CO2 toxicity and the effects of seawater acidification on health status, histopathology, immunity and disease resistance in Asian Seabass (Lates calcarifer)’Posts Tagged 'reproduction'
Acute CO2 toxicity and the effects of seawater acidification on health status, histopathology, immunity and disease resistance in Asian Seabass (Lates calcarifer)
Published 12 January 2026 Science ClosedTags: biological response, fish, laboratory, molecular biology, mortality, physiology, reproduction
Strength and duration of diel pH and dissolved oxygen cycles control the survival and performance of early life stage North Atlantic bivalves (Mercenaria mercenaria, Crassostrea virginica, Argopecten irradians and Mytilus edulis)
Published 9 January 2026 Science ClosedTags: biological response, growth, laboratory, mollusks, mortality, multiple factors, North Atlantic, oxygen, physiology, reproduction, respiration
Highlights
- Cycling from nocturnal hypoxia – acidification to mild hyperoxia- hypocapnia reduced larval survival in all experiments.
- Cycling from nocturnal hypoxia – acidification to normoxia- normocapnia reduced survival of larvae in 50 % of experiments.
- Nocturnal hypoxia and acidification caused increased clearance and respiration rates in juvenile mussels.
- The impacts of diel DO and pH cycles on early life stage bivalves depend on cycle duration, cycle intensity, and species.
Abstract
Many economically important bivalves spawn during the summer months when diel cycles of dissolved oxygen (DO) and pH occur in estuaries. Little is known, however, regarding how cycles of differing durations and magnitudes affect these organisms. Here, larval bivalves (Mercenaria mercenaria, Crassostrea virginica, Argopecten irradians) and juvenile mussels (Mytilus edulis) were exposed to cycles of low DO and pH of varying duration (4-, 6-, 8-, and 12-h) and strength (moderate: DO range ∼ 6 mg L−1, pH range ∼ 0.6 and severe: DO range ∼ 10 mg L−1, pH range ∼ 0.9) compared to positive (normoxic and normocapnic) and negative (hypoxic and acidified) static controls. Growth, survival, respiration and clearance rates were measured. During experiments, 12 h of nocturnal hypoxia and acidification coupled with mildly hyperoxic (∼11.3 mg L−1 DO) and hypocapnic (∼8.13 pH) conditions by day significantly reduced survival in larval C. virginica, M. mercenaria, and A. irradians in all experiments (p < 0.05), while 12 h of nocturnal hypoxia and acidification without hyperoxic and hypocapnic conditions did so in only half of experiments indicating that hyperoxia and hypocapnia were additional and significant stressors. Six hours of low DO/pH significantly reduced survival in only 16 % of experiments, indicating that larval bivalves are more impacted by longer duration and greater magnitude cycles of DO and pH compared to cycles of shorter duration or lower magnitude. Across species, M. mercenaria larvae were more resilient to nocturnal hypoxia and acidification than A. irradians and C. virginica. The growth and survival of juvenile M. edulis were unaffected by nocturnal hypoxia and acidification but mussels experienced significantly increased clearance and respiration rates under these conditions (p < 0.01) evidencing physiological mechanisms for coping with these stressors. Collectively, this study demonstrates that the impacts of diel DO and pH cycles on early life stage bivalves are dependent upon cycle duration, cycle intensity, bivalve life stage, and bivalve species.
Continue reading ‘Strength and duration of diel pH and dissolved oxygen cycles control the survival and performance of early life stage North Atlantic bivalves (Mercenaria mercenaria, Crassostrea virginica, Argopecten irradians and Mytilus edulis)’Combined effects of ocean acidification, warming, and salinity on the fertilization success in an Arctic population of sea urchins
Published 9 January 2026 Science ClosedTags: Arctic, biological response, echinoderms, laboratory, multiple factors, reproduction, salinity, temperature
Anthropogenic stressors, including ocean acidification (OA), ocean warming (OW), and salinity changes, are rapidly altering marine ecosystems, with Arctic regions being particularly vulnerable. This study investigates the combined effects of these stressors on the fertilization success of the green sea urchin (Strongylocentrotus droebachiensis) from Kongsfjorden, Svalbard. We exposed gametes to various levels of pH, temperature, and salinity to assess their individual and combined impacts on fertilization performance. Our results show that temperature and pH significantly influenced fertilization success, with temperature having the strongest effect, while salinity had no significant impact. A significant statistical interaction between temperature and pH indicated that warming enhanced fertilization more effectively at higher pH levels, while low pH suppressed this increase. To compare the relative influence of each stressor, we used a conceptual model based on standardized slopes, which supported temperature as the dominant driver, followed by pH. These findings highlight the importance of considering the effects of combined stressors when assessing marine organism responses to climate change, especially in polar ecosystems. Our study underscores the need for further research into the mechanisms driving these combined effects, given that Arctic ecosystems face accelerated environmental changes.
Continue reading ‘Combined effects of ocean acidification, warming, and salinity on the fertilization success in an Arctic population of sea urchins’Reproduction of the viviparous marine isopod Cirolana harfordi held in seawater with raised temperature and lowered pH
Published 2 January 2026 Science ClosedTags: biological response, crustaceans, growth, laboratory, mortality, multiple factors, reproduction, temperature, zooplankton
Cirolanid isopods play important ecological roles as predators and scavengers, but when populations increase, they can form swarms that attack fish and humans. Understanding how the reproduction of cirolanid isopods will be affected by future warmer and more acidic oceans is therefore important. Samples of the viviparous species Cirolana harfordi were held in 4 combinations of 2 temperatures (18 and 24°C) and 2 pH levels (7.7 and 8.1), and the development of embryos and mancas was investigated by microscopic examination of each pregnant female through the transparent ventral cuticle of their thorax. Higher temperature increased the rate of development, thereby reducing pregnancy duration and accelerating the growth of mancas postpartum. By contrast, increased acidity had no significant effect on these parameters and had no deleterious effects on the development of the mancas. Higher temperature did not have a significant effect on the number of postpartum mancas after the 22 weeks that the adults spent in treatments. Increased temperature and/or lowered pH had no effect on the adult survival or growth. These data are in keeping with the hypothesis that C. harfordi may be able to withstand future warmer and more acidic oceans. Longer-term studies are needed to determine whether decreasing pregnancy durations in higher temperatures increases the number of times females can become pregnant over their lifetime, potentially leading to greater population numbers.
Continue reading ‘Reproduction of the viviparous marine isopod Cirolana harfordi held in seawater with raised temperature and lowered pH’Shell proteome plasticity assists oyster larval biomineralization in adverse carbonate chemistry
Published 30 December 2025 Science ClosedTags: biological response, laboratory, mollusks, morphology, mortality, physiology, reproduction
Bivalve planktonic development is a critical phase during which larvae must secrete the first calcium carbonate shell, the prodissoconch I (PD I). As PD I formation is in close contact with seawater, this process can be negatively affected by adverse seawater carbonate chemistry. It is hypothesized that bivalves can regulate shell formation under environmental stress through biologically controlled biomineralization involving a complex extracellular shell proteome. However, the plasticity of this regulatory mechanism during PD I development is unknown. We assessed the PD I shell proteome of the Hong Kong oyster (Magallana hongkongensis) in carbonate chemistry that was adverse or favorable for biomineralization to understand the regulatory capacity of larval shell formation. While survival rates were not affected in adverse carbonate chemistry, there were significant changes, including the upregulation of several calcium-binding proteins and downregulation of proton-generating processes and putative calcification inhibitors. With 198 sequences, the oyster larval shell proteome was twice to over six times larger than those reported for other bivalve species at the same developmental stage. However, in adverse carbonate chemistry, the oyster larval shells were thinner and smaller, and protein diversity decreased to 131 sequences, with overall lower functional redundancy and reduced expression of structural proteins, indicating potential trade-offs. The proteomic and shell structural data also suggest that direct cellular control and biologically induced mechanisms, which will require further investigation, may be involved in PD I formation.
Continue reading ‘Shell proteome plasticity assists oyster larval biomineralization in adverse carbonate chemistry’Interactive effects of ocean acidification and benthic biofilm composition on the early development of the European abalone Haliotis tuberculata
Published 23 December 2025 Science ClosedTags: biological response, communityMF, laboratory, mollusks, morphology, multiple factors, North Atlantic, performance, phytoplankton, reproduction, respiration
Ocean acidification (OA) and associated shifts in carbonate chemistry represent major threats to marine organisms, particularly calcifiers. OA effects can be influenced by other environmental variables, including the biotic environment. This study investigated the individual and interactive effects of OA and algal density, acting through biofilm composition, on post-larval and juvenile abalone (Haliotis tuberculata). In a three-month factorial experiment, abalone were exposed from metamorphosis onward to two pH conditions (ambient 8.0 and reduced 7.7) and two initial densities of the green alga Ulvella lens on settlement plates. Biofilm biomass and composition were characterised using spectral reflectance and HPLC pigment analysis. Biological (density, length), physiological (respiration rate), behavioural (hiding response) and shell parameters (colour, surface corrosion, strength) of abalone were measured throughout the experiment. Biofilm biomass and composition remained relatively stable under both pH conditions, though greater variability in algal biomass occurred at low initial Ulvella density. Post-larval density and total length decreased significantly under low pH, while high Ulvella density reduced juvenile length at 80 days, likely due to competition between algal groups. A pH × Ulvella interaction affected shell fracture resistance and colouration, but not metabolism or behaviour, indicating that juvenile abalone maintained vital functions. Overall, the results confirm the sensitivity of early H. tuberculata stages to moderate OA (−0.3 pH units) and highlight indirect macroalgal effects through changes in diatom communities. In natural environments, the capacity of abalone to cope with future OA will depend on complex trade-offs between direct acidification effects and food-related biotic interactions.
Continue reading ‘Interactive effects of ocean acidification and benthic biofilm composition on the early development of the European abalone Haliotis tuberculata’Ocean acidification reduces juvenile snow crab, Chionoecetes opilio, survival but does not affect growth or morphometrics
Published 18 December 2025 Science ClosedTags: biological response, crustaceans, laboratory, morphology, mortality, North Pacific, reproduction
Highlights
- Snow crab were reared at 3 pHs for 396 days.
- Low pH did not affect size at molt.
- Low pH did not affect intermolt period.
- Survival was lower at a pH of 7.5 than at ambient or pH 7.8.
- Snow crab are moderately sensitive to ocean acidification.
Abstract
Anthropogenic release of CO2 and its subsequent dissolution in the oceans results in a decrease in the pH of seawater, known as ocean acidification, which can negatively affect marine organisms. Little is known about the response of snow crab, Chionoecetes opilio, to reduced pH. Juvenile snow crab were captured in the Bering Sea and exposed to three different pH treatments (Ambient (pH ∼7.95), pH 7.8, and pH 7.5) for 396 days at a constant temperature of 4 °C with thirty crabs randomly assigned to each treatment. Crabs were checked daily for molting or mortality. Wet mass and carapace morphometrics were measured after every molt. Reduced pH did not affect the intermolt duration, the carapace width after each molt, or wet mass of the crabs after each molt, giving no indication that growth rate was changed by reduced pH. There also was no change in morphometrics caused by reduced pH. However, the mortality rate of crabs held at pH 7.5 was 40 % higher than those held at pH 7.8 or Ambient. Such a substantial increase in mortality without accompanying sublethal effects is surprising; individuals susceptible to reduced pH might have died early in the experiment, or that differences in growth rate might have become apparent with longer exposure. Regardless, juvenile snow crab are somewhat sensitive to ocean acidification, although, consistent with studies at other life-history stages, snow crab may be more resistant to changes in pH than other Alaska crab species.
Continue reading ‘Ocean acidification reduces juvenile snow crab, Chionoecetes opilio, survival but does not affect growth or morphometrics’A global meta-analysis reveals consistently negative effects of ocean acidification on marine cultured bivalves: implications for future bivalve aquaculture
Published 16 December 2025 Science ClosedTags: biological response, calcification, fisheries, growth, mitigation, mollusks, mortality, performance, physiology, reproduction, review
The exponential rise in atmospheric CO₂ driven by human activities is accelerating climate change and causing ocean acidification (OA). While the effects of elevated CO₂ on a wide range of marine species have been well documented, the implications of OA for bivalve aquaculture have received comparatively little attention. Using a multi-level meta-analytical approach, we evaluated the impacts of two elevated pCO₂ levels—classified as high and extreme—on cultured bivalves, based on 266 observations from 24 species across tropical and temperate regions. Overall, both elevated pCO₂ levels negatively affected bivalves, reducing survival, growth, feeding rates, development, and calcification. Larvae were generally more vulnerable than juveniles and adults. Our analyses further indicated that temperate bivalves were more sensitive to OA than tropical and subtropical counterparts. Among taxa, clams were the most vulnerable under high CO₂ emission scenarios, whereas scallops were the most sensitive under extreme pCO₂ levels. We also discuss potential mitigation strategies for the bivalve aquaculture industry. With advancements in local and regional monitoring, coupled with targeted measures such as buffering sites, selective breeding, and integrated multi-trophic aquaculture, the adverse effects of OA on bivalve farming could be mitigated.
Continue reading ‘A global meta-analysis reveals consistently negative effects of ocean acidification on marine cultured bivalves: implications for future bivalve aquaculture’Stressed overwintering bottleneck hypothesis: ocean warming and acidification synergistically disrupt Arctic zooplankton overwintering
Published 1 December 2025 Science ClosedTags: Arctic, biological response, crustaceans, laboratory, molecular biology, mortality, multiple factors, physiology, reproduction, respiration, temperature, zooplankton
Ocean warming (OW), driven by the influx of warm Atlantic water masses, and acidification (OA) are threatening Arctic marine ecosystems. However, their potential synergistic effects are poorly understood, especially during the Polar Night when marine species are particularly vulnerable to stressors. Here, we tested our novel Stressed Overwintering Bottleneck Hypothesis (SOBH): warming will disrupt the overwintering of the keystone pan-Arctic copepod Calanus glacialis, a pivotal secondary producer, by impairing fitness-related traits underpinning survival and reproduction. We exposed C. glacialis to current and projected future OW levels (0 °C and 4 °C) and OA levels (pH 8.0 and 7.4-7.3) for 53 days during the mid-Arctic Polar Night. We assessed survival, development, and physiological and molecular mechanisms (oxygen consumption, lipid depletion, the expression of nine targeted genes related to oxidative stress and damage repair, and DNA damage). OW alone did not affect C. glacialis mortality; however, OA increased copepod survival at 0 °C. Notably, their combined effects (OWA) synergistically doubled mortality, as predicted by SOBH. Warming also accelerated moulting from copepodite stage V to adulthood in December, and increased respiration, exhausted lipid reserves entirely by early March, approximately one to four months before the spring algal bloom, further supporting SOBH. DNA damage and gene expression patterns indicated low investment in maintenance and damage repair. Collectively, these findings reveal hidden mechanisms by which OW and OA synergistically threaten overwintering Calanus copepods by drastically increasing mortality, accelerating moulting, raising metabolic rates, and causing early lipid depletion. These effects generate cross-seasonal phenological mismatches among overwintering survival, energy reserves, reproduction, and primary production. Such stressed overwintering bottlenecks in foundational secondary producers like Calanus copepods provide novel explanations for how OW and OA can constrict Arctic marine food webs. At a broader perspective, SOBH highlights how multiple stressors induced overwintering disruption could reshape pan-Arctic and global biodiversity.
Continue reading ‘Stressed overwintering bottleneck hypothesis: ocean warming and acidification synergistically disrupt Arctic zooplankton overwintering’Acidification-mediated perturbations of developmental pathways and life-stage transitions in Artemia salina
Published 27 November 2025 Science ClosedTags: biological response, crustaceans, fisheries, laboratory, mortality, reproduction
Projected increases in atmospheric carbon dioxide are anticipated to induce a 0.3–0.5 unit decline in oceanic pH by the year 2100, posing a significant threat to marine ecosystems. This study investigated the sub lethal effects of simulated ocean acidification on the ontogenetic success of Artemia salina, a key trophic link in aquaculture systems. A controlled, in vitro experiment employing a Completely Randomized Design (CRD) was conducted, maintaining constant temperature, salinity, and dissolved oxygen. Embryonic development and larval survival were assessed across a gradient of pH levels, representing projected future ocean acidification scenarios. Preliminary data indicate a negative correlation between decreasing pH and both hatching success and larval survivorship. Further investigations are warranted to elucidate the long-term ecological consequences of ocean acidification on Artemia salina populations and their role in aquaculture.
Continue reading ‘Acidification-mediated perturbations of developmental pathways and life-stage transitions in Artemia salina’The larva-Symbiodiniaceae association at risk: putative impacts of climate change on reproduction, dispersal, and recruitment in coral reefs
Published 24 November 2025 Science ClosedTags: biological response, BRcommunity, cnidaria, corals, mollusks, physiology, phytoplankton, porifera, reproduction, review
The relationship between invertebrates and Symbiodiniaceae dinoflagellates is the ecological foundation of diverse and productive coral reef ecosystems. Climate change-induced breakdown of this partnership, i.e., bleaching, is repeatedly driving widespread reef degradation. Thus, the future trajectory of this ecosystem depends on the reproduction and dispersal capacity of invertebrate-Symbiodiniaceae symbiosis. This review examines how climate change affects the biology of larvae from three invertebrate phyla—Porifera, Cnidaria, and Mollusca—that host Symbiodiniaceae, focusing on differences in symbiont transmission mode, symbiont location, and the larvae´s reliance on these associations. Due to limited research on Porifera and Mollusca hosts, most knowledge of larvae-Symbiodiniaceae associations stems from coral larvae patterns. The myriads of combinations of genetic and ecophysiologically distinct hosts and symbionts result in highly context-dependent responses to warming, but symbiotic larvae tend to be more susceptible to oxidative stress and show higher mortality than aposymbiotic larvae. While ocean acidification has little direct effect on the algal symbionts, it impacts larvae variably, especially calcifying larvae (e.g., mollusks), which suffer from impaired calcification and higher mortality. Climate change also impairs the reproductive processes of Symbiodiniaceae-bearing invertebrates, reducing gamete output, causing asynchronous spawning, and lowering larval survival. These effects will result in a persistent decline in recruitment with increased larval retention, consequently reducing reef connectivity and genetic diversity, thus weakening ecosystem resilience. This underscores the urgent need to hasten knowledge on larval ecology under climate change and the functional role of symbionts to better inform marine conservation planning and to incorporate larval ecology in the future predictions.
Continue reading ‘The larva-Symbiodiniaceae association at risk: putative impacts of climate change on reproduction, dispersal, and recruitment in coral reefs’Newly discovered CO2 (carbon dioxide) vent cave drives r-strategy shift in a Mediterranean aphotoendosymbiotic coral
Published 14 November 2025 Science ClosedTags: abundance, biological response, chemistry, corals, field, growth, Mediterranean, morphology, reproduction, vents
Highlights
- Characterization of an unexplored CO2 vent cave
- CO2 vents chemical-physical parameters affect ecological traits of calcifiers
- Aphotoendosymbiotic solitary coral naturally inhabiting a CO2-rich gas environment.
- Prolonged acidified conditions did not affect C. inornata growth rate
- Shift towards an r-demographic strategy in response to acidified conditions
Abstract
Submarine CO2 volcanic vents represent peculiar environments with varying seawater chemical-physical parameters that may affect the ecological traits of calcifying organisms, such as growth and demographic characteristics. The present study focused on exploring the growth and population dynamics of a temperate, solitary and aphotoendosymbiotic coral Caryophyllia inornata (Duncan, 1878) living in a CO2 vent cave at 14 m depth. The volcanic emissions in and around the cave led high levels of pCO2, resulting in lower calcium carbonate saturation state (Ωa: 2.1–2.2) values compared to those observed in the ambient seawater of the Mediterranean Sea, not affected by venting activity. Prolonged acidified conditions (pHT: 7.5) did not affect C. inornata growth rate but resulted in a population with higher percentage of juvenile individuals, lower average ages and a lower age at maximum biomass percentage, thus suggesting a transition in its population dynamics towards an r-demographic strategy. This study provides a detailed characterization of a previously unexplored CO2 vent cave, highlighting the importance of these sites as natural laboratories to offer valuable insights into understanding the full ecological impact of aphotoendosymbiotic corals under ocean acidification.
Continue reading ‘Newly discovered CO2 (carbon dioxide) vent cave drives r-strategy shift in a Mediterranean aphotoendosymbiotic coral’Mothers know best: maternal signaling boosts larval resilience under ocean acidification conditions
Published 12 November 2025 Science ClosedTags: adaptation, biological response, fisheries, molecular biology, mollusks, morphology, mortality, otherprocess, physiology, reproduction
Highlights
- Environmental priming effectively rescued larval phenotype under OA conditions.
- Egg ‘omics were investigated to elucidate mechanism of priming across generations.
- Clam egg lipidomes were largely unperturbed by maternal low-pH exposure.
- Differentially expressed genes were identified in eggs of low-pH primed clams.
Abstract
Bivalve aquaculture is a growing sector worldwide, producing sustainable animal protein to meet growing demand from consumers. Yet, the industry remains vulnerable to environmental changes that can impact their product across life stages, especially at the larval stage. Parental priming, or the exposure of broodstock to adverse environmental conditions as they undergo gametogenesis, holds promise as a method to increase resilience in bivalve offspring. We exposed Manila clam (Ruditapes philippinarum) broodstock to low pH conditions (pH 7.4 for 78 days during gametogenesis). Larvae were produced from primed (low pH) and unprimed (ambient pH) broodstock and exposed to ambient or low pH conditions in a full factorial design. Larval phenotype in response to low pH was partially rescued by broodstock priming: larvae from low pH-exposed broodstock had better survival and growth than larvae from broodstock held under ambient conditions. Clam egg lipidomic and transcriptomic analyses were performed to determine the physiological differences associated with broodstock environmental conditions. Egg lipid abundance profiles were not significantly different between parental treatments. The egg transcriptome revealed 48 differentially expressed transcripts associated with parental environmental conditions. These genes are involved in important processes for early larval physiology, including metabolism, cell cycle, and transcriptional regulation. Broodstock clams were minimally impacted by their exposure to low pH for 78 days, however we show here that subtle maternal signals may contribute to the vastly improved larval performance observed under low pH conditions.
Continue reading ‘Mothers know best: maternal signaling boosts larval resilience under ocean acidification conditions’Impact of crustose coralline algae, ocean acidification, and ocean warming on larval pinto abalone settlement and juvenile survival
Published 11 November 2025 Science ClosedTags: algae, biological response, BRcommunity, communityMF, laboratory, mollusks, morphology, mortality, multiple factors, North Pacific, reproduction, temperature
Highlights
- Ocean acidification reduced pinto abalone settlement and survival in the hatchery.
- Ocean acidification is likely a greater threat than warming to Washington pinto abalone.
- Use of a natural settlement inducer improves abalone settlement and survival.
- Coralline algae may improve survival of pinto abalone under ocean acidification.
Abstract
Since 1994, Washington State (USA) has experienced a 97 % drop in the native pinto abalone population. Since 2007, conservation aquaculture initiatives have been underway to return the population to a self-sustaining level. Successful restoration, however, depends on both the ability to successfully raise juveniles in hatchery settings and the capacity of outplanted pinto abalone to survive and reproduce in the wild as threats of ocean acidification and warming continue to increase. Crustose coralline algae (CCA) can play an important role in restoration efforts by acting as natural inducers of larval settlement. Additionally, studies have shown that CCA can create a boundary layer with elevated pH, potentially providing a refuge for benthic species. We examined the settlement of pinto abalone under different environmental conditions (7.90 pH/14 °C (ambient), 7.90 pH/18 °C, 7.55 pH/14 °C; and 7.55 pH/18 °C) using two substrates: CCA-covered rocks and clean rocks with GABA (a chemical settlement inducer). Low pH negatively impacted larval settlement. Though settlement was higher with CCA than with GABA, this difference was not statistically significant. Juvenile survival was negatively impacted by low pH, but positively impacted by CCA presence, demonstrating the potential of CCA to increase juvenile pinto abalone survival and ameliorate the negative effects of low pH. Using CCA in hatchery culture and selecting sites with CCA cover for pinto abalone outplants may improve the efficiency of restoration in Washington.
Continue reading ‘Impact of crustose coralline algae, ocean acidification, and ocean warming on larval pinto abalone settlement and juvenile survival’Dulse seaweed Devaleraea mollis mitigates effects of ocean acidification on larval Pacific oysters Magallana gigas
Published 21 October 2025 Science ClosedTags: algae, biological response, BRcommunity, chemistry, laboratory, mitigation, molecular biology, mollusks, morphology, North Pacific, reproduction
Ocean acidification (OA), driven by upwelling and climate change, can negatively impact the ecological and economic contribution of marine calcifiers along coasts worldwide. OA interferes with calcification, particularly in early life stages, causing mortality, reduced growth, and morphological abnormalities in shellfish such as the Pacific oyster (Magallana gigas). This issue is gaining traction as climate change intensifies, placing shellfish in wild populations and farms alike at risk. Macroalgal photosynthesis by seaweed such as Pacific dulse (Devaleraea mollis) has been proposed to provide small-scale OA refuges, but few controlled experiments quantify this effect, and none have focused on larval shellfish. This study examines the potential for Pacific dulse to mitigate OA and its effects on Pacific oyster larvae. Under continuous light for 23 days, the presence of dulse resulted in a consistent increase in seawater aragonite saturation state by 0.1-0.9, and pH by 0.1-0.5 units, depending on OA condition. Newly fertilized oysters were reared for 48 hours in the absence or presence of dulse under treatments corresponding to ambient (pH 7.8, 450 μatm CO₂), future OA (pH 7.6, 800 μatm CO₂), and future OA + upwelling (pH 7.4, 1200 μatm CO₂) seawater conditions. Dulse fully mitigated OA effects on larval size that ranged from decreases of 5% to 10%. Under the future OA + upwelling treatment, dulse presence reduced the odds of underdeveloped oyster larvae at 14 hours post fertilization (hpf), and larvae with hinge abnormalities at 24 hpf, by over 50%. Dulse induced minor changes to immune response gene expression at 48 hpf. These findings highlight the benefits of seaweed when adjacent to organisms sensitive to OA. These findings will be particularly useful for shellfish farms, habitat restoration efforts, and ocean stewardship practices as a potential mitigation strategy under the changing climate.
Continue reading ‘Dulse seaweed Devaleraea mollis mitigates effects of ocean acidification on larval Pacific oysters Magallana gigas’DNA methylation plasticity drives copepod resilience to coastal high pCO2 and cadmium pollution under multigenerational exposure
Published 20 October 2025 Science ClosedTags: adaptation, biological response, crustaceans, laboratory, metals, molecular biology, mortality, multiple factors, North Pacific, otherprocess, reproduction, zooplankton
Highlights
- Fluctuating acidification caused the most Cd multigenerational toxicity in copepods.
- The adverse effects of acidification and Cd tended to intensify during F1-F3.
- The copepods potentially adapted to combined exposure in F4.
- DNA hypomethylation rendered copepods presenting the adaptive potential.
ABSTRACT
The vast majority of coastal organisms have been facing multigenerational scenarios of fluctuatingly high pCO2 and Cd pollution in their natural habitats. However, the adaptive capacity of these organisms to such combined stressors and the underlying mechanisms remain poorly understood. In this study, we conducted a multigenerational experiment (F1-F4) to investigate the adaptive responses of the marine copepod Tigriopus japonicus to combined fluctuatingly high pCO2 and Cd exposure, along with the associated mechanisms. Our findings revealed that steady high pCO2 aggravated Cd multigenerational toxicity, and it was more under fluctuating acidification. Notably, by the F4 generation, copepods potentially adapted to the combined stressors. Through transcriptomic and DNA methylation analyses of copepods from the F1 and F4 generations, we found that under combined exposure, F1 copepods likely reallocated more energy to counteract Cd toxicity; however, DNA hypermethylation inhibited Cd exclusion and detoxification/stress response pathways, ultimately compromising development and reproduction. In contrast, in the F4 generation, DNA hypomethylation enhanced processes such as cuticle repair program, compensatory mechanism (e.g., detoxification and immune response), and reproduction, consequently increasing the copepod’s fitness. These findings reveal an epigenetic basis for phenotypic acclimatization, offering marine copepods a supplementary mechanism to cope with combined stressors.
Continue reading ‘DNA methylation plasticity drives copepod resilience to coastal high pCO2 and cadmium pollution under multigenerational exposure’The bacterial community composition of American lobster (Homarus americanus) embryos and recently hatched larvae held under different temperature and acidification conditions
Published 16 October 2025 Science ClosedTags: biological response, BRcommunity, community composition, crustaceans, laboratory, molecular biology, multiple factors, North Atlantic, otherprocess, prokaryotes, reproduction, temperature
Previous research investigating the microbial community of American lobster embryos has long led researchers to believe this habitat comprised only a select few bacterial taxa. However, using 16S rRNA gene sequencing, we show this community to be more diverse than previously thought. We investigated how the bacterial communities of American lobster embryos and larvae change over embryogenesis and hatching in response to two environmental variables. Ovigerous female lobsters caught from Maine and Massachusetts were held under varying temperature and pH regimes that approximated observed and predicted warming and ocean acidification conditions in the Gulf of Maine (GoM) and Southern New England (SNE). The bacterial microbiome associated with the lobster embryos was quantified from two-time points during the experiment, and larvae were collected within 12 hours of hatching. Alpha diversity increased with each life history stage, and embryo and larvae microbiomes shared little community overlap with that in the surrounding tank water. Neither environmental conditions nor lobster origin significantly altered bacterial communities, with life history stage driving alpha and beta diversity. Embryos and larvae shared three core bacterial members identified as members of the genera Rubritalea, Delftia, and Stenotrophomonas. American lobster embryos and larvae appear to have a highly selective microhabitat for bacteria that is not altered by environmental conditions. This leads us to wonder what role the microbiome may have on a developing lobster, and where the microbiome is originating if not from the surrounding seawater.
Continue reading ‘The bacterial community composition of American lobster (Homarus americanus) embryos and recently hatched larvae held under different temperature and acidification conditions’Low pH does not impact reproductive success but leads to negative carry-over effects between parents and larvae in a Mediterranean gastropod
Published 15 October 2025 Science ClosedTags: biological response, laboratory, Mediterranean, mollusks, morphology, reproduction
Understanding how marine organisms respond to ocean acidification across all life stages is essential for assessing the future resilience of ecosystems. We investigated the effects of long-term exposure to low pH conditions (pHT ranging from 7.95 to 7.22) on the reproductive traits and intracapsular development of Hexaplex trunculus, a predatory Mediterranean gastropod. Spawning success, fecundity, and capsule morphology were not affected by pH. However, larval development was significantly impaired at pHT lower than 7.51, with observed delayed development and fewer larvae developing successfully to the hatchling stage. Cross-transplantation of spawns between pHs indicated a negative carryover effect of parental exposure to low pH on larval development, although this was partially reversible when spawns were transferred back to the ambient pH. Notably, we observed inter-individual variability in larval growth, suggesting that phenotypic plasticity or genotype-specific tolerance may play a role in moderating sensitivity to future ocean acidification. Our study highlights the importance of considering parental exposure, natural pH variability, and within-population variation when assessing species responses to global drivers
Continue reading ‘Low pH does not impact reproductive success but leads to negative carry-over effects between parents and larvae in a Mediterranean gastropod’Impact of ocean acidification on the biology of marine bivalves
Published 14 October 2025 Science ClosedTags: biological response, mitigation, mollusks, physiology, reproduction, review
Ocean acidification, resulting from increased atmospheric CO₂ levels, poses a significant threat to marine ecosystems, particularly to shell-forming organisms such as marine bivalves. This review synthesizes current knowledge regarding the impacts of ocean acidification on bivalves, including oysters, clams, and mussels, focusing on their physiology, development, and ecological interactions. Acidification impairs shell formation, disrupts energy metabolism, alters feeding and respiration patterns, and inhibits the growth and recruitment of larvae. These changes can destabilize bivalve populations and impair the ecosystem services they offer, such as water filtration, habitat creation, and support for fisheries and aquaculture. The report discusses potential strategies to mitigate the impacts of climate change, including the reduction of carbon emissions, selective breeding, and habitat management. This underscores the necessity of interdisciplinary research to comprehend the long-term impacts of climate change and to promote sustainable resource management that benefits the environment.
Continue reading ‘Impact of ocean acidification on the biology of marine bivalves’Effects of multiple stressors on embryos and emerging larvae of the American lobster
Published 14 October 2025 Science ClosedTags: adaptation, biological response, crustaceans, laboratory, morphology, multiple factors, North Atlantic, otherprocess, physiology, reproduction, temperature
Environmental changes in the ocean can impose significant physiological costs and morphological changes to many marine organisms, and early life stages such as eggs and larvae are predicted to be particularly vulnerable to climate change drivers including warming and acidification. Although sensitivity to ocean change stressors during development has the potential to influence the performance, and ultimately the recruitment, of postlarvae and juveniles, the nature and strength of physiological modifications during embryo development is understudied in the ecologically and economically important American lobster Homarus americanus. We investigated the long-term, interactive impacts of ocean acidification and ocean warming on the development and physiology of brooded lobster embryos. We exposed ovigerous females to a combination of 2 temperatures and 2 pH levels for 5 mo, throughout which we measured development, metabolic rate, biochemical composition, and enzyme activity in their brooded embryos. The physiology of American lobster embryos appears to be robust to ocean acidification conditions but sensitive to warming, particularly for metabolic traits. We also found that warming induced a reduction in the size of freshly hatched larvae. Understanding how environmental change influences these early life stages of lobsters can improve predictions for how this species will fare in a changing ocean environment.
Continue reading ‘Effects of multiple stressors on embryos and emerging larvae of the American lobster’
