Posts Tagged 'reproduction'

Combined effects of ammonium and pH on sea urchin embryogenesis: insights for sediment quality assessment

Published 30 April 2026 Science Leave a Comment
Tags: , , , , , , , ,

Highlights

  • Reduced pH enhances ammonium toxicity on sea urchin embryos in filtered seawater.
  • In elutriates ammonium is a major driver of P. lividus embryotoxicity.
  • Data support setting ammonium thresholds in sediment quality frameworks.
  • Ocean acidification potentially increases ammonium toxicity for sea urchin larvae.

Abstract

Ammonium is a key component of coastal marine systems, originating from both natural and anthropogenic sources, with possible toxic effects on marine organisms depending on the concentration and pH. This study evaluates, for the first time, the combined effects of ammonium and seawater acidification on early development of the sea urchin Paracentrotus lividus under both laboratory conditions and exposure to environmental matrices derived by dredged sediments from harbor area. Embryos were incubated with increasing concentrations of ammonium in filtered seawater at pH 8.1 and 7.6, as well as in sediment elutriates from the Pescara harbor (Adriatic Sea, Italy), selected as a case study with relevant concentrations of ammonium (0.1–3.5 mg/L). A combined effect between ammonium and pH was observed, with increasing ammonium toxicity by ∼20% at pH 7. Moreover, in sediment elutriates, ammonium affect sea urchin embryo development, with EC50 ranging between 1.388 and 1.538 mg/L NH4+ at pH 8.1 and 7.6, respectively, without significant differences due to pH. Chemical analyses of sediments confirmed low levels of trace metals and organic pollutants, indicating that ammonium is the primary driver of embryotoxicity without a direct toxic effect of other contaminants. The results further underscore the need to integrate ammonium assessment into sediment quality frameworks and for management strategies, particularly in the context of future ocean acidification, to safeguard the early life stages of sensitive marine invertebrates.

Continue reading ‘Combined effects of ammonium and pH on sea urchin embryogenesis: insights for sediment quality assessment’

Ocean acidification and harmful algal blooms combine to suppress the growth and survival of North Atlantic bivalve larvae

Published 29 April 2026 Science Leave a Comment
Tags: , , , , , , , ,

While harmful algal blooms (HABs) and ocean acidification (OA) are environmental factors that can impair bivalves, the manner in which these two stressors may act and interact to impact bivalve larvae is poorly understood. This study exposed larvae of hard clams (Mercenaria mercenaria) and Eastern oysters (Crassostrea virginica) to a range of pCO2 levels found in estuaries (400–3,000 µatm) and three harmful algae, Alexandrium catenella, Dinophysis acuminata, and Margalefidinium polykrikoides, at densities found during HABs (500–7,000 cells mL-1), with one HAB species exposure per experiment. The combined OA and HAB treatment significantly reduced larval survival in all 21 experiments by 91 ± 4.6% (SE) compared to controls and reduced larval sizes in 92% of experiments by 40 ± 3.5%. Cultured M. polykrikoides had a stronger negative effect on larvae than cellular equivalent bloom populations. Densities of D. acuminata >750 cells mL-1 reduced larval survival and size (p < 0.01), but the addition of OA to D. acuminata did not suppress survival further. While the combined A. catenella and OA treatment reduced larval growth and survival at all densities (p < 0.01), A. catenella alone did not impact M. mercenaria survival or size at or below 1,000 cells mL-1 and did not impact C. virginica at any density. Oyster larvae were less impacted than hard clams by OA (33 vs. 67% of experiments) and by HABs (67 vs. 100% of experiments). Given the very low survival of bivalve larvae when exposed to combined HABs and OA in all experiments (<0.1–5%), bivalve restoration and conservation efforts should seek to avoid regions that experience these co-stressors.

Continue reading ‘Ocean acidification and harmful algal blooms combine to suppress the growth and survival of North Atlantic bivalve larvae’

The impact of climate change on lobster production: a systematic synthesis of literature

Published 6 April 2026 Science Closed
Tags: , , , , , , , ,

Climatic impact-drivers are projected to change in coastal and marine regions globally, especially towards the fisheries production of the commercially important global shellfish, such as lobster species. Thus, there is an immediate need for ongoing, rigorous systematic review that continuously assesses and analyzes the risk of climatic factors towards lobsters’ production (i.e., growth, reproduction, etc.). A global relevant literature was analyzed from the inception to 31st December 2024. The review targets commercially important lobster, across various life history stages. The current study presents a systematic analysis of the research articles on lobster growth, reproduction, and development from relevant literature through two main academic databases, Scopus (n = 284) and Web of Science (n = 310). During literature search, duplicate articles were removed manually (n = 177). A total of 46 research articles were generated from the strict systematic selection process at various life history stages of lobsters. Climate change elements such as temperature, salinity, carbon dioxide, pH, and hypoxia significantly impact ovigerous females, reproduction, hatching success, larval stages, and juvenile development of lobsters. As global climate change intensifies, the reproductive and developmental capacity of lobster populations may be increasingly compromised, particularly in early life history stages. To date, a comprehensive synthesis of reproductive and biological impacts across taxa and regions has been lacking. This review provides a foundational reference for future assessments and adaptation strategies for sustainable management of lobsters under climate change.

Continue reading ‘The impact of climate change on lobster production: a systematic synthesis of literature’

Combined ecotoxicity of microplastics and crude oil co-pollutants: occurrence, distribution and its synergistic impact with ocean acidification on Artemia franciscana

Published 3 April 2026 Science Closed
Tags: , , , , , , , , ,

Microplastics (MPs) are recognized as a global concern, with specific attention shifted towards marine MPs pollution. This particular study investigates the abundance and distribution of crude oil-loaded microplastics (COMPs) along the Chennai coastline, Tamil Nadu, India and evaluates their combined toxicological effects with ocean acidification on Artemia franciscana. Spatial analysis revealed that Ennore Creek exhibited the highest MP concentration (10.82 ± 0.2 items/L). Polypropylene was recorded as the predominant polymer type followed by low density polyethylene and polyethylene terephthalate, with particle size ranging from 250 to 500 µm. COMPs were detected across all sampling sites, with concentrations declining from Ennore Creek (0.21 ± 0.03 items/L) to Kasimedu Beach (0.10 ± 0.02 items/L). The adsorption of crude oil on MPs is primarily mediated by physical interaction with multi-layer adsorption behaviour. The results highlighted that increase in MP concentration and decrease in seawater pH significantly induced acute toxicity and oxidative stress responses in A. franciscana. At pH 7.8, experimental groups exposed to 0.5 mg/mL of COMPs developed higher ROS, SOD and catalase activity (p<0.001). Whereas control groups alone showed significant increase in oxidative stress responses at lower pH level such as pH 7.8 and 8.0. Combined exposure of COMPs and low pH conditions significantly increased oxidative damages in A. franciscana and affected its hatching ability. The observations from this study emphasize the urgent need for integrated monitoring and further research to explore combined toxicological effects of MPs and ocean acidification to other marine organisms as well.

Continue reading ‘Combined ecotoxicity of microplastics and crude oil co-pollutants: occurrence, distribution and its synergistic impact with ocean acidification on Artemia franciscana’

Ocean acidification affects the timing of puberty and the reproductive output in a marine temperate fish

Published 2 April 2026 Science Closed
Tags: , , , , , , , ,

Ocean acidification (OA) is a major climate-related threat to fish that can disrupt the regulation of the reproductive axis of fish, impacting reproductive success. However, previous studies have only focused on a single reproductive cycle and reported increased fecundity in some species exposed to OA. Since acclimation over several reproductive cycles can occur, it is necessary to evaluate successive reproductive cycles for predicting the actual resilience of species to OA. In this study we assessed the impact of lifetime exposure to different ocean pH/pCO2 levels (Current condition, Moderate OA and High OA) on the sexual maturation and spawning phenology of the European sea bass, over its two first reproductive periods. We tested the hypothesis that OA would exert its greatest impact at the onset of puberty (first reproduction). Accordingly, High OA exposure induced an earlier onset of puberty in both sexes, resulting in a longer spawning period and an increased fecundity. These effects were reduced during the second reproductive season. However, OA affected egg quality and sperm motility profile during the second reproductive season, leading to a total mortality at hatching of embryos spontaneously produced. This mortality was not observed in embryos produced through hormone-induced oocyte maturation and in vitro fertilisation. These results suggest that OA affects the regulation of oocyte maturation and/or the synchronisation of eggs and sperm release. The OA-driven shift in spawning may misalign with optimal environmental conditions for offspring survival. This increases the population’s vulnerability and could favour species whose reproduction is more resilient to OA.

Continue reading ‘Ocean acidification affects the timing of puberty and the reproductive output in a marine temperate fish’

Impacts of ocean acidification on marine zooplankton: a review of physiological, developmental, and reproductive responses

Published 31 March 2026 Science Closed
Tags: , , , , , ,

Acidification. The increasing levels of carbon dioxide CO₂ in the atmosphere are leading to ocean acidification, and this is altering the chemical content of marine water and is endangering life in the oceans. The examples of marine zooplankton, including Copepods, Pteropods, krill, and larvae of invertebrates are essential to the pelagic food webs and carbon cycles, even though they differ in their tolerance to low PH concentration and high pCO₂ levels. Early developmental phases are particularly vulnerable, with them showing retardation in developmental stages, reduced hatch rates, physical deformities as well as a lack of calcification. Higher carbon dioxide CO₂ levels interfere with the acid-base balance, increase oxidative stress and alter the allocation of metabolism, leading to trade-offs that lower growth, reproduction and survival rates. Calcifying organisms such as the pteropods are highly susceptible whereas some of the non-calcifying copepods exhibit a level of physiological resilience. Negative effects of other stressors may be affected by increased temperature, oxygen depletion, and nutrient enrichment which may further compound negative effects. There is some evidence that there is some possible acclimation in the short term and that there might be transgenerational plasticity but we do not understand adaptive capacity in the long term. Knowledge gaps exist in regard to multigenerational response, non-calcifying and gelatinous species and how physiological plasticity occurs. Species-specific responses are an important aspect of predictive models to estimate the impact of the ecosystem and guide conservation efforts. To ensure marine ecosystems remain stable as ocean acidification continues, vulnerable zooplankton should be safeguarded to preserve tropic structure, nutrient cycling, and nutrient stability.

Continue reading ‘Impacts of ocean acidification on marine zooplankton: a review of physiological, developmental, and reproductive responses’

Resilient adults but vulnerable larvae: demographic pathways of chiton decline under ocean acidification

Published 26 March 2026 Science Closed
Tags: , , , , , , , , , , , , , ,

Highlights

  • Natural CO₂ seep systems showed reduced intertidal chiton abundance.
  • Adult chitons showed resilience to acidification in field and lab experiments.
  • Larval survival and recruitment were strongly impaired under acidified seawater.
  • Population declines are linked to early life-stage vulnerability.
  • Loss of chitons may reduce grazing and bulldozing, reshaping intertidal communities.

Abstract

Ocean acidification (OA) is a major threat to marine calcifiers; however, the sensitivity across taxa and life stages remains elusive. In this study, we combined field surveys of natural CO₂ seeps with laboratory exposure, transplantation, and larval settlement experiments to assess the effect of OA on chitons, a group of calcifying grazers and bulldozers that play critical roles in the structure of rocky intertidal ecosystems. Field surveys revealed approximately 98.6% reduction in chiton (Acanthopleura loochooana, Liolophura japonica, and Acanthochitona rubrolineata) abundance at acidified habitats (pH 7.6), despite greater microalgal food availability and no detectable increase in predator abundance. Laboratory CO₂-exposure experiments showed no direct effect of OA on adult A. loochooana survival, which is consistent with the presence of protective structural features in the valves that confer resistance to dissolution. Transplant experiments revealed no evidence of increased adult A. loochooana mortality in the acidified habitats (pH 7.6). In contrast, larvae showed pronounced sensitivity to OA, with acidified seawater (pH 7.6) reducing larval settlement by approximately 81.5% compared to control conditions (pH 8.1); early life stages were the most vulnerable. These findings suggest that OA-associated decline in chiton abundance is mainly mediated by impaired recruitment rather than by direct adult mortality, predation, or food limitation. Given the role of chitons as grazers and bulldozers, their loss could substantially change intertidal community dynamics by decreasing grazing pressure and disturbing algal and microbial assemblages. Our findings underscore the criticality of considering life-stage vulnerability and ecological function when evaluating the ecosystem-level consequences of OA.

Continue reading ‘Resilient adults but vulnerable larvae: demographic pathways of chiton decline under ocean acidification’

Tolerance of egg and yolk-sac larval yellowfin sole (Limanda aspera) to ocean warming and acidification

Published 23 March 2026 Science Closed
Tags: , , , , , , , , , , ,

Yellowfin sole (Limanda aspera) support the largest flatfish fishery in the world and contribute substantially to the eastern Bering Sea (EBS) flatfish catch. The EBS has been warming and acidifying, trends that are expected to intensify into the future. Sustainable management of yellowfin sole requires an understanding of how yellowfin sole respond to environmental change, which can be assessed through controlled laboratory investigations. Across four independent trials, yellowfin sole embryos and larvae were incubated at one of six experimental treatments spanning three temperatures (9°C, 12°C, and 15°C) and two pCO2 target levels (low and high), and a range of organismal and physiological responses were measured. Embryonic daily mortality rates and metabolic rates increased with increasing temperature but were not affected by ocean acidification. At- hatch and at- yolk absorption, morphometric measurements (length, dry weight, myotome height, and yolk area) were temperature- sensitive, but the response differed across the four trials. There was a consistent increase in length- based growth and yolk absorption rates with increasing temperature across trials. All morphometric and rate- based measurements were not affected by ocean acidification. Yellowfin sole metabolic enzyme activities were measured at- yolk absorption. Lactate dehydrogenase (anaerobic metabolism) and β- hydroxyacyl CoA dehydrogenase (fatty acid metabolism) both increased with increasing temperature, indicating elevated energy demand. Citrate synthase (aerobic metabolism) declined with increasing pCO2 levels, indicating potential metabolic suppression. Overall, embryonic and larval yellowfin sole demonstrated relatively high tolerance to ocean warming and acidification. We hypothesize the variation in temperature responses across the trials may be driven by maternal effects, which could support tolerance to future ocean conditions.

Continue reading ‘Tolerance of egg and yolk-sac larval yellowfin sole (Limanda aspera) to ocean warming and acidification’

Ocean acidification disrupts the biomineralization process in the oyster Crassostrea virginica via intracellular calcium signaling dysregulation

Published 20 March 2026 Science Closed
Tags: , , , , , , ,

Calcium is a key component in the shell and skeleton structure, serving as a second messenger for regulating biomineralization across many species. Ocean acidification (OA) is well-studied for causing shell dissolution in marine bivalve species by disordering calcium deposition. However, the regulatory pathway of calcification affected by OA remains unclear. This study assessed eastern oyster (Crassostrea virginica) to determine how calcium signaling responds to elevated pCO2 and influences shell formation. Under elevated pCO2, increased calcium influx was found in mantle epithelial cells, followed by the upregulation of calmodulin, a primary sensor of intracellular calcium. Expression levels of shell matrix proteins (SMPs), representing shell construction conditions, were significantly upregulated in the CO2-induced mantle cells. Larval C. virginica exhibited developmental stage-dependent alterations in calcium signaling and SMPs disarrangement stimulated by pCO2. Pharmaceutical blockage of the calcium binding on calmodulin induced abnormal expression of downstream genes and shell matrix changes consistent with those caused by elevated pCO2. Restored SMPs expressions in CO2-treated mantle cells were achieved by rescuing the level of calcineurin, a downstream effector of calmodulin. These findings suggest that shell deformities under OA are primarily caused by the disruption of the calcium-calmodulin signaling pathway in mantle epithelial cells.

Continue reading ‘Ocean acidification disrupts the biomineralization process in the oyster Crassostrea virginica via intracellular calcium signaling dysregulation’

Influence of ocean warming and acidification on juveniles of the true giant clam, Tridacna gigas, and its microalgal symbionts

Published 19 March 2026 Science Closed
Tags: , , , , , , , , , ,

Uncontrolled carbon dioxide emissions from human activities contribute to ocean warming and acidification. These alterations in ocean chemistry threaten marine organisms, such as the true giant clam, Tridacna gigas, which is already imperiled due to overharvesting and habitat destruction. To gain an understanding of the physiological and molecular responses of T. gigas and its symbiotic dinoflagellates to ocean warming and acidification, we subjected juvenile individuals to different treatments simulating predicted seawater pH (7.6 and 8.0) and temperature (28°C, 30°C, 32°C and 34°C) levels for the next century. Juvenile giant clams were able to tolerate sustained exposure to temperatures of up to 32°C and pH as low as 7.6, while exposure to higher temperature (34°C), regardless of pH level, resulted in total mortality after a week. However, symbiosis was compromised even in the sublethal treatments, as indicated by the decrease in Symbiodiniaceae density and changes in symbiont gene expression. Symbionts significantly upregulated genes involved in splicing, translation, fatty acid metabolism, and DNA repair, which may constitute an adaptive response, while downregulating genes involved in photosynthesis and transmembrane transport, suggests impaired transfer of photosynthates to the host. These findings demonstrate the vulnerability of the juvenile T. gigas holobiont to heat stress, highlighting the critical importance of continued conservation and management alongside efforts to mitigate global changes in ocean conditions to safeguard this iconic marine bivalve.

Continue reading ‘Influence of ocean warming and acidification on juveniles of the true giant clam, Tridacna gigas, and its microalgal symbionts’

Effects of rapid acidification in marine seawater: focus on Actinopterygii

Published 17 March 2026 Science Closed
Tags: , , , , , , ,

Highlights

  • The review reports physiological, behavioural, developmental and reproductive effects.
  • Studies on Actinopterygii exposure to various pCO₂ levels are integrated.
  • Fishes show strong species- and life-stagesingle bondspecific vulnerability to high pCO2.
  • Most experiments with extreme CO₂ levels are short-term, limiting current knowledge.

Abstract

The progressive acidification of the world’s oceans has led to widespread concern regarding the potential consequences for marine biosphere. As a result, most research has been focused on the steady increase of dissolved CO₂ and consequent acidification thus on calcifying species while less attention has been paid to the physiological and developmental impacts of teleost fish. However, rapid and massive release of carbon dioxide (CO₂) into the marine environment may occur due to both natural and anthropogenic causes. This review specifically examines the outcomes of rapid but confined CO₂ emissions, with a focus on their role in accelerating the local acidification of seawater and on the related effects on Actinopterygii. It examines the impacts of elevated CO₂ levels on marine fishes, also emphasizing the lack of experimental evidence on embryonic larval and larval phases, which are highly vulnerable to acid-base imbalances and related physiological disruptions. A broad review of literature published between 1963 and 2025, on fishes’ exposure to varying CO₂ conditions, highlights pronounced variability in responses across species and developmental stages. Early life phases frequently exhibit reduced survival, skeletal and sensory anomalies, and shifts in metabolic demand. Although some taxa demonstrate compensatory adjustments, the resulting energetic costs and physiological trade-offs can limit growth, reproduction, and long-term resilience. Advancing our understanding of fish vulnerability and adaptive potential under seawater acidification of marine fishes in an acidifying environment requires long-term, ecologically relevant designs and integrated approaches that link multiple life stages and biological scales.

Continue reading ‘Effects of rapid acidification in marine seawater: focus on Actinopterygii’

Interactive effects of ocean acidification and settlement biofilm on the early development of the European abalone Haliotis tuberculata

Published 3 March 2026 Science Closed
Tags: , , , , , , , , , ,

Highlights

  • Interactive effects of OA and settlement biofilm were investigated on juvenile abalone.
  • Post-larval density and total length decreased significantly under lower pH.
  • Biofilm composition induced indirect effects through changes in diatom biomass.
  • (pH × Ulvella) interaction affected abalone shell resistance and colouration.

Abstract

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 effects of OA and algal density, acting through an Ulvella-conditioned settlement biofilm, on post-larval and juvenile abalone (Haliotis tuberculata). In a three-month full 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. Biofilm biomass and composition assessed with pigment proxies 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 unit) and highlight indirect macroalgal effects through changes in diatom cover. In natural environment, 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 settlement biofilm on the early development of the European abalone Haliotis tuberculata’

Short-term mechanisms, long-term consequences: molecular effects of ocean acidification on juvenile snow crab

Published 20 February 2026 Science Closed
Tags: , , , , , , , , , ,

Understanding how marine species tolerate acidified conditions is critical for predicting biological responses to ocean change. A recent one-year experiment (Long 2026) found that juvenile snow crab (Chionoecetes opilio) maintain growth and molting under acidification (pH 7.8, 7.5), and survival begins to decline only after ∼250 days under severe acidification (pH 7.5). In this companion study, we characterized whole-transcriptome responses after 8 hours and 88 days of exposure to identify molecular mechanisms underlying short-term tolerance and chronic effects of ocean acidification. The immediate transcriptional response involved strong activation of genes associated with mitochondrial metabolism and biogenesis, protein homeostasis, cuticle maintenance, and immune modulation, processes shared between moderate and severe treatments but of greater magnitude under severe acidification. After 88 days, expression patterns diverged, revealing sustained upregulation of stress- and damage-mitigation pathways in the severe treatment (pH 7.5) compared to the moderate treatment (pH 7.8). These findings indicate that crabs in severe acidification are likely to experience chronic OA stress that precedes outward physiological effects, and provides a mechanistic basis for delayed mortality. We further highlight potential early indicators of chronic acidification stress in snow crab, among which a gene likely coding for carbonic anhydrase 7 (CA7, GWK47_031192) appears to be the most promising biomarker.

Continue reading ‘Short-term mechanisms, long-term consequences: molecular effects of ocean acidification on juvenile snow crab’

Molecular indicators of warming and other climate stressors in larval Pacific cod

Published 19 February 2026 Science Closed
Tags: , , , , , , ,

Recent marine heatwaves in the Gulf of Alaska negatively impacted Pacific cod (Gadus macrocephalus) through a series of failed year classes and poor recruitment to the fishery. Experimental work by Slesinger et al. (2024) corroborated the hypothesis that warming directly impacts recruitment by increasing larval mortality rates. In this companion study, we applied transcriptomics with larvae from Slesinger et al. (2024) to better understand how warming affected their physiology and identify potential mechanisms contributing to mortality. RNASeq data reveal that warm-exposed larvae have unique gene expression profiles that may reflect high levels of inflammation, lipid dysregulation or depletion, and altered development of visual systems and neurological pathways. Warming may therefore cause a metabolic mismatch whereby energy-demanding activities (development, inflammation, growth) exceed energy production capacity despite access to prey. We also report the less pronounced transcriptional differences in larvae exposed to cold, acidification, and a combination of stressors reflecting future climate scenarios. This information will guide future genetic and experimental work that will ultimately inform recruitment forecasts in years with conditions similar to those tested here.

Continue reading ‘Molecular indicators of warming and other climate stressors in larval Pacific cod’

Resilience of the macroalgae Gongolaria barbata under ocean acidification: physiological responses and restoration perspective

Published 3 February 2026 Science Closed
Tags: , , , , , , , , ,

The increasing CO2 concentration is a major cause of the climate change phenomenon. Concurrently, the same increase is leading to ocean acidification (OA), which is projected to decrease seawater pH by 0.4 units by 2100. Here we investigated the potential impacts of OA on the canopy-forming brown macroalga Gongolaria barbata from the Venice Lagoon. One-year-old individuals were maintained in mesocosms under two pH levels: 8.1 (current ambient value) and 7.7 (the end-of-the-century value predicted under the current scenario of anthropogenic CO2 emissions). The physiological responses of the algae were assessed during the experiment in terms of oxygen production and consumption, and maximal PSII photochemical efficiency. At the end of the experiment, we analyzed the percentage of mature receptacles, algal growth rate and the total polyphenolic content and antioxidant capacity as indicators of the stress response. The significant decrease in polyphenolic content indicates the impairment of the defence mechanisms, which could make the algae more vulnerable to grazing under acidified conditions. Yet, conversely, our results suggest that changes in pH levels do not significantly affect the physiological processes, growth or fertility of the algae. These findings suggest that while OA may weaken defence mechanisms, the preservation of physiological and reproductive functions would still support the potential of G. barbata populations from the Venice Lagoon to act as donor sources for restoration efforts, highlighting their resistance to the acidified conditions expected in the future.

Continue reading ‘Resilience of the macroalgae Gongolaria barbata under ocean acidification: physiological responses and restoration perspective’

Parental exposure to ocean acidification impacts the larval development and transcriptome of the Pacific oyster Crassostrea gigas

Published 2 February 2026 Science Closed
Tags: , , , , , , , ,

Atmospheric carbon dioxide (CO2) levels are escalating at an unprecedented rate, leading to the phenomenon of ocean acidification (OA). Parental exposure to acidification has the potential to enhance offspring resilience through cross-generation plasticity. In this study, we analyzed larval growth and transcriptomic profiles in the Pacific oyster, Crassostrea gigas, a species of significant ecological relevance, under both control and elevated CO2 conditions experienced by their parental generation. Our findings indicate that the oyster populations exposed to OA exhibited a higher incidence of abnormalities during the D-shaped larval stage, followed by accelerated growth at the eyed stage. Through a comparative transcriptomic investigation of eyed larvae (25 d after fertilization), we observed that parental exposure to OA substantially influenced the gene expression in the offspring. Genes associated with lipid catabolism and shell formation were notably upregulated in oysters with parental OA exposure, potentially playing a role in cross-generational conditioning and conferring resilience to OA stressors. These results underscore the profound impact of OA on oyster larval development via cross-generational mechanisms and shed light on the molecular underpinnings of cross-generation plasticity.

Continue reading ‘Parental exposure to ocean acidification impacts the larval development and transcriptome of the Pacific oyster Crassostrea gigas’

Transgenerational effects of extreme weather on Manila clam resilience: implications for aquaculture sustainability

Published 27 January 2026 Science Closed
Tags: , , , , , , , , , , , , ,

Highlights

  • SAE+MHW synergistically impaired clams during reproduction.
  • Progeny exhibited lasting developmental delays and high mortality.
  • Long-term physiological dysfunction persisted into later life stages.
  • Compound extremes threaten bivalve aquaculture resilience.

Abstract

Extreme environmental events, including sea acidity extremes (SAE) and marine heatwaves (MHW), pose increasing threats to coastal aquaculture species. This study examined the individual and combined effects of SAE and MHW on Manila clams (Ruditapes philippinarum) and their transgenerational impacts. Adults exposed to SAE+MHW showed reduced survival, decreased condition index, lower clearance rate (CR) and assimilation efficiency (AE), elevated ammonia excretion (ER), and negative scope for growth, indicating disrupted energy budgets. Reproductive output and gonadal development were also compromised. Offspring from stressed parents exhibited lower larval survival, stunted shell growth, reduced metamorphic success, smaller settlement size, reduced juvenile (6-month-old) survival rate and disrupted energy homeostasis, revealing persistent transgenerational impacts on development and energy homeostasis. These findings suggest that parental exposure to synergistic SAE+MHW alters energy allocation and may involve epigenetic mechanisms, ultimately impairing offspring fitness. Overall, our study demonstrates that compound extreme events can severely affect metabolic resilience and cross-generational performance in Manila clams, highlighting the need for multigenerational assessments, selective breeding, and aquaculture strategies to enhance climate resilience.

Continue reading ‘Transgenerational effects of extreme weather on Manila clam resilience: implications for aquaculture sustainability’

Integrated biochemical profiling, comparative transcriptome and weighted gene co-expression network analysis to explore the response mechanism of global warming and ocean acidification to the stress of Sepia esculenta larvae

Published 16 January 2026 Science Closed
Tags: , , , , , , , ,

Highlights

  • Multi-angle analysis of Sepia esculenta under global warming and ocean acidification.
  • Stress enhanced the immune defense and antioxidant defense of S.esculenta.
  • The hub genes closely related to stress resistance were identified and screened out.
  • Provided a theoretical basis for the breeding of fine varieties and pond culture.

Abstract

The Sepia esculenta has high economic value and nutritional value, and accounts for a high proportion of the catch of cephalopods in China ‘s coastal waters. Global warming and ocean acidification, as major environmental problems currently facing the world, have a serious negative influence on the survival and breeding of S. esculenta. Therefore, in the research, transcriptome sequencing and biochemical quantitative analysis were performed on the larvae of S. esculenta after high temperature, low pH and combined stress at different time points, and the differential expressed genes (DEGs) and response mechanisms were identified. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that these DEGs were mainly involved in a large number of immune-related biological processes and signaling pathways, including Immune response、Phagocytosis、Regulation of DNA-templated transcription and Positive regulation of DNA-templated transcription. Then, we further explored the functional relationship between these DEGs by constructing weighted gene co-expression network and protein-protein interaction networks. We identified ten hub genes including HSP90AA1, ALDH1L1, VPS13A, MAPK8IP1 and KDM6A. These hub genes may play an important role in the face of high temperature, low pH and their combined stress at different times. Our findings not only elucidate the molecular response mechanisms of S. esculenta to environmental stress and delineate the key regulatory pathways underlying its adaptation, but also provide a theoretical foundation for advancing pond cultivation.

Continue reading ‘Integrated biochemical profiling, comparative transcriptome and weighted gene co-expression network analysis to explore the response mechanism of global warming and ocean acidification to the stress of Sepia esculenta larvae’

Effects of pH on growth and anatomical characters of tapeseagrass (Enhalus acoroides (Linnaeus f.) Royle)

Published 14 January 2026 Science Closed
Tags: , , , , , , , , ,

Enhalus acoroides (Linnaeus f.) Royle or tape seagrass plays a vital role in tropical seagrass meadows, especially in Thailand. While ocean acidification negatively affects many marine species, it may benefit tropical seagrasses. E. acoroides relies on seed dispersal for sexual reproduction, and pH variations may influence seedling development. This study examined the effects of pH levels (6, 7, 8, and 9) on E. acoroides seedling growth over 8 weeks in controlled aquariums. All treatments showed 100% seed germination during the first week. By week 2, no significant differences in biomass were observed, but by week 8, seedlings at pH 6 had the highest dry weight (0.21±0.01 g), as well as the greatest leaf number (5.64±0.15 leaves), leaf length (23.39±2.06 mm), and leaf width (4.74±0.14 mm). One-way ANOVA revealed significant differences in growth by week 8. Lower pH levels enhanced shoot and root growth, while higher pH increased root number but reduced root length. Chlorophyll content analysis showed no correlation with pH after 8 weeks. Anatomical examination revealed tannin cells, starch granules, and thick cell walls in the mesophyll, with an enlarged exodermis in lower pH treatments, suggesting an adaptation for stabilizing in muddy, acidic conditions. These findings indicate that pH influences the growth and adaptation of E. acoroides seedlings, highlighting the species resilience to acidification. Its adaptive capacity is crucial for management, as E. acoroides can survive acidification and continue providing habitat, preserving ecosystem balance.

Continue reading ‘Effects of pH on growth and anatomical characters of tapeseagrass (Enhalus acoroides (Linnaeus f.) Royle)’

Assessing impacts of extreme climate and weather events on endangered pearl oysters Pinctada maxima

Published 13 January 2026 Science Closed
Tags: , , , , , , , ,

Extreme climate and weather events in the ocean, especially ocean acidification (OA) and marine heatwaves (MHWs), have strikingly accelerated in the past decades, yet their compound consequences remain poorly understood. The pearl oyster (Pinctada maxima), an endangered keystone species in Indo-Pacific reef ecosystems, is highly vulnerable to such events. Here, we assessed how OA-stressed P. maxima juveniles responded to MHWs (+3 °C), based on a total of 100 individuals exposed to two weeks. Oysters reared at pH 7.7 significantly increased activities of energy-metabolizing enzymes (T-ATP and NKA) in response to MHWs, whereas both enzymes significantly decreased, albeit CMA increased, at pH 7.4. MHWs significantly depressed antioxidant enzyme activities, such as SOD at both pH levels, resulting in elevated MDA levels indicative of lipid peroxidation. Contrasting responses of immune enzymes (ACP and AKP) to MHWs were seen in oysters grown under moderately and severely acidified conditions. MHWs, also, significantly depressed expression levels of key genes related to cellular metabolism (ATP1A, ATP1B, ND5, ATPeV1F and ATPeF1A) and those associated with antioxidant defence (SOD, SOD1, SOD2, Hsp70, Hsp90 and CAT), in particular when stressed at pH 7.4. Taken together, our findings suggest that intensifying MHWs can constrain the ability of P. maxima to cope with OA and likely accelerate further population decline in this era of unprecedented climate change.

Continue reading ‘Assessing impacts of extreme climate and weather events on endangered pearl oysters Pinctada maxima’

Subscribe

Search

  • Reset

OA-ICC Highlights

Resources