Posts Tagged 'echinoderms'

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

Published 30 April 2026 Science Leave a Comment
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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.

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Short-term tolerance to ocean acidification of the sub-antarctic sea-urchin arbacia dufresnii

Published 29 January 2026 Science Closed
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The accumulation of anthropogenic CO2 in the ocean is impacting the carbonate system chemistry in seawater, particularly in polar regions. Acidified seawater can impair the echinoderms internal regulation of pH due to an increase in hydrogen ions concentration, potentially affecting growth, and calcification, among other physiological activities. The goal of this work was to assess the effects of Ocean Acidification (OA) on Arbacia dufresnii, a sub-Antarctic sea urchin species. Adult specimens were exposed to three pH treatments: 7.4, 7.7, and 8.0 (control), for 21 up to 23 days. We assessed spine regeneration, a proxy of calcification, by cutting spines at the base of the shaft and evaluating the magnesium content, height, and weight of the regenerated part. The coelomic fluid was sampled for pH assessment and magnesium and calcium content analysis. The RNA/DNA ratio, a proxy of metabolic activity, was assessed in the gonads and body walls. The spine regenerated weight was significantly correlated to regenerated height but not to treatments. The coelomic fluid pH (6.77 ± 0.34) did not differ between treatments (pANOVA = 0.15). No significant differences were observed between treatments regarding RNA/DNA ratio in both body wall (pANOVA = 0.65) and gonads (pKruskal-Wallis = 0.34), the spine regenerated height (pANOVA = 0.35) and Mg regenerate content (pANOVA = 0.58). Our results suggest that A. dufresnii owns physiological mechanisms to cope with OA conditions during short-term exposure.

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Combined effects of ocean acidification, warming, and salinity on the fertilization success in an Arctic population of sea urchins

Published 9 January 2026 Science Closed
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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.

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Effects of long-term ocean acidification exposure on the structural, mineralogical, and mechanical properties of sea urchin (Echinometra spp.) skeletons at a natural volcanic CO2 seep

Published 23 December 2025 Science Closed
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Two decades of mesocosm studies document generally negative effects of ocean acidification (OA) on adult sea urchin growth, feeding performance, skeletal structure, and strength. Whether experimental observations hold true in natural systems will determine whether they can be extrapolated to predict responses under ecologically relevant contexts. Here, we employ a suite of imaging, chemical, and mechanical techniques to examine the skeletal properties of two closely related sea urchin species (genus Echinometra) living at a natural carbon dioxide (CO2) seep in Japan. Test plates and spines from urchins living under elevated CO2 conditions were thinner, more porous, and had less biomineral than those at reference sites; however, tooth structure was resilient to elevated CO2. The magnesium content of the test and spines did not differ between sites; however, they exhibited reduced nanohardness and became more brittle under elevated CO2. Together, altered structural and mechanical properties may compromise the protective function of urchin skeletons at the CO2 seep. These responses have implications for ecosystem structure if urchin function is suppressed at the population level. Future work might explore the repeatability of these findings across successive species and localities to recognize generality, its limits, and the conditions that mediate the influence of OA.

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Morphological adjustments enable sea urchins to sustain calcified structure function under ocean acidification

Published 10 December 2025 Science Closed
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Ocean acidification can reduce the size of calcified structures produced by marine calcifiers, raising questions about their competitiveness and persistence in future oceans. Yet, size reduction in calcified structures may represent a plastic response to ocean acidification if these structures remain functional. To test this hypothesis and examine whether morphological plasticity can influence the functionality of calcified structures, we assessed the effects of ocean acidification on the morphological, mechanical and chemical properties of the calcified structures of a sea urchin species prevailing at natural CO2 vents. We found that the rigid shells covering sea urchins’ bodies (‘tests’) were thinner and that they had smaller teeth and lower spine density at vents, but the mechanical performance of these calcified structures (mechanical resilience, wear resistance and bending strength) was maintained, possibly mediated by the capacity of sea urchins to sustain acid-base balance for calcification (i.e. increased Na/Ca). Our findings suggest that such morphological shifts in calcified structures may enable sea urchins to maintain structural performance under ocean acidification. Since ocean acidification is a slow process relative to the life cycle of sea urchins, some sea urchin species may acclimate, or even adapt, to ocean acidification so that their populations and ecological functions can persist in a future high-CO2 world.

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Dynamics of a coral reef system under climate change

Published 28 November 2025 Science Closed
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Highlights

  • It is established that a new a stochastic coral-starfish model with global warming and ocean acidification.
  • It is revealed that the change in global warming has a decisive impact on the dominant position of corals and starfish.
  • It is found that the variation of pH is able to destabilize coral-starfish interactions.

Abstract

The intensification of global warming and ocean acidification are important factors affecting coral reef degradation, however, their impact mechanisms on coral reef system are still unclear. In this paper, we study the dynamics of a stochastic coral-starfish model considering the factors of global warming and ocean acidification, where the stochastic environmental fluctuation is characterized by mean-reverting Ornstein-Uhlenbeck (OU) process. A key advantage of considering global warming and ocean acidification in coral reef systems is that it can accurately describe the dynamic mechanisms of coral-starfish interactions, providing a scientifically reliable theoretical basis for exploring the evolutionary succession of coral reef systems. The main purpose of this paper is to investigate how global warming and ocean acidification affect the dynamic mechanisms of coral reef systems in the presence and absence of stochastic disturbances. Mathematically, we mainly study the critical threshold conditions for the transcritical bifurcation, saddle-node bifurcation, and Hopf bifurcation of deterministic coral reef system, as well as the existence of ergodic stationary distribution, precise expressions of probability density function, persistent in the mean, and stochastic extinction dynamics in stochastic coral reef system, which in turn provide a theoretical basis for numerical simulations. Numerical analysis indicates that the variations of global warming and ocean acidification can generate a great influence on the coral-starfish dynamics with and without OU process. Significantly, it is found that coral growth dominates under the increasing global warming effect, while starfish growth dominates under the decreasing global warming effect in a randomly perturbed environment. Furthermore, the change of pH has capacity to destabilize coral-starfish interactions, while the intensified global warming can lead to the extinction of starfish. These findings may contribute to the studies of potential strategies for protecting coral reef ecosystems under the impact of climate change.

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Gut microbial community plasticity as a climate shield mediating sea cucumber resilience to ocean acidification and warming

Published 28 October 2025 Science Closed
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Ocean acidification (OA) and ocean warming (OW) pose escalating threats to marine ecosystems, particularly to benthic organisms, such as sea cucumbers, that play pivotal roles in nutrient cycling and sediment health. Existing studies have mostly focused on the physiological responses of sea cucumbers, yet overlooked the critical roles of both gut microbial communities and metabolites in the host’s responses under environmental stress. Herein, a mesocosm experiment was constructed and analyzed by using integrated gut microbiome and metabolomics approaches to investigate the responses of sea cucumbers Apostichopus japonicus to OA and OW. Results revealed that microbial community plasticity underpins holobiont adaptation, with warming restructuring gut microbiota toward thermotolerant taxa, whereas acidification enriches alkalinity-modulating Rhodobacteraceae and Halioglobus sp.. Metabolomic profiling identified 43 amino acid derivatives that exhibit significantly increased concentrations in the OA and OW groups. These derivatives include upregulated N-methyl-aspartic acid and γ-glutamyl peptides, which stabilize macromolecules and enhance redox homeostasis. Conversely, antioxidative metabolites, such as ergothioneine and L-homocystine, are suppressed, reflecting trade-offs between energy allocation and stress protection. In OW group, the antioxidant synthesis pathway is shifted to energy metabolism related to heat tolerance, whereas in OA group, energy is preferentially used for alkalinity regulation pathways rather than oxidative stress defense. Changes in microbial community structure mechanistically explain the trends in metabolite concentrations, as the proliferation of Vibrio spp. in the OW group drives lysine catabolism, leading to a significant increase in L-saccharopine levels. The reduction of Bacteroidetes in the OA group is correlated with the downregulation of L-homocystine, suggesting that pH-driven microbial interactions are disrupted. These findings demonstrate that gut microbiota reconfigure community structure and metabolic landscapes to buffer hosts against climate stress synergies, highlighting the importance of microbiome-mediated resilience in marine ecosystems under global climate change.

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Effect of ocean acidification on the metabolism and behavior of tropical sea cucumbers

Published 16 September 2025 Science Closed
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In recent years, CO₂ emitted by human activities has continued to rise. The ocean absorbs these CO₂ and has caused seawater acidification. It is expected that the pH of the sea surface will drop by 0.3~0.4 by the end of this century. Tropical sea cucumbers are the “engineers” of the subsea ecosystem, promoting organic degradation and nutrient circulation through feeding disturbances. This study reviews the effects of marine acidification on the metabolism and behavior of tropical sea cucumbers. Studies have shown that under low pH conditions, sea cucumbers have increased respiratory metabolic pressure, digestive enzyme activity is reduced, and more energy is used to maintain the acid-base balance in the body, and their growth and reproduction are limited. At the same time, sea cucumber feeding rate and defense behavior are inhibited, and habitat distribution may change. These changes will have a chain effect on tropical ecosystems such as coral reefs, weaken the nutrient circulation function, and affect ecological balance. In-depth research on the impact mechanism of marine acidification on sea cucumbers will help predict the response of marine ecosystems under climate change and provide scientific basis for resource conservation and aquaculture management.

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What doesn´t kill you makes you stronger: the sea urchin Arbacia lixula living on volcanic CO2 vents

Published 1 September 2025 Science Closed
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Anthropogenic CO2 emissions drive ocean acidification (OA), which reduces seawater pH and carbonate ion availability, threatening calcifying organisms such as sea urchins. This study examines the long-term effects of OA on Arbacia lixula using a natural volcanic CO2 vent at Fuencaliente, La Palma (Canary Islands) as an analogue of future conditions. We analyzed the external morphology, skeletal strength, mineralogy, and growth of A. lixula across three sites that differed consistently in mean pH (from 8.14 to 7.65 during low tide). Sea urchins from low pH conditions were smaller, with shorter spines and reduced jaw-to-diameter ratios, yet their tests showed higher fracture resistance than those from ambient conditions. Additionally, individuals from acidified zones showed altered growth dynamics, with fewer growth rings. Skeletal changes and growth alterations are consistent with modified mineralization processes and dietary shifts toward non-calcareous food sources. This study highlighting the morphological plasticity and resilience of A. lixula under persistent natural acidification, offering insight into how sea urchins may respond in a high-CO2 ocean.

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Metabolomics analysis provides new insights into the impacts of long-term ocean acidification and warming on the sensory qualities of sea urchin (Strongylocentrotus intermedius) gonads

Published 26 August 2025 Science Closed
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Highlights

  • Ocean acidification and warming (OAW) alter the color of sea urchin gonads.
  • OAW reduce the size and weight of sea urchin gonads.
  • OAW alter contents of flavor and odor-related compounds in sea urchin gonads.
  • OAW affect the quality of female gonads more seriously than that of males.

Abstract

Sea urchin gonads are popular raw, ready-to-eat seafood known for their fresh, sweet taste and high nutritional value. To investigate the impacts of ocean acidification and warming (OAW) on the sensory qualities of sea urchin gonads, farmed Strongylocentrotus intermedius were incubated separately and jointly in acidic (ΔpHNBS = −0.5 units) and thermal (ΔT = +3.0 °C) seawater for 90 days under lab-controlled conditions based on the ocean pH and temperature for 2100 projected by the Intergovernmental Panel on Climate Change (IPCC). Sensory properties (gonad size, color, and flavor-related metabolites) were subsequently determined and compared between groups. The results showed that: 1) The gonad size and gonad index (GI) decreased sharply (−49 % in female; −46 % in male) under OAW conditions in both sexes of adult S. intermedius. There were significant negative additive effects of acidification and high temperature on the GI. 2) OAW had no significant interaction effects on five gonadal color-related parameters; however, the redness (a*) of male gonads was significantly less than that of female gonads in both the separate and joint OAW groups. 3) Significant alterations to metabolome profiles, exhibiting sex-specific variations, were observed in adult S. intermedius incubated under separate/joint OAW conditions. Twenty-two significantly differentially expressed metabolites (SDMs) related to color, odor, and flavor were identified, primarily enriched in metabolic pathways associated with the biosynthesis and accumulation of odor and flavor compounds. To sum up, the data from this study indicate that OAW affect sensory qualities of sea urchin gonads negatively especially the gonads of females.

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Molecular markers of stress in the sea urchin embryo test: analysing the effect of climate change and pollutant mixtures on Paracentrotus lividus larvae

Published 15 August 2025 Science Closed
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Highlights

  • Combined effects of ocean stressors on sea urchin larvae were analysed.
  • RNA-seq revealed key transcriptional changes under stressor combinations.
  • Larval growth and deformities worsened with acidification and warming.
  • Biomarkers for early detection of stress in marine larvae were identified.
  • Insights contribute to predicting organismal responses to climate change.

Abstract

Climate change and pollution represent critical stressors for marine ecosystems, particularly for calcifying organisms such as the sea urchin Paracentrotus lividus. This study examines the combined effects of ocean acidification (OA), ocean warming (OW), and microplastics (MP) loaded with chlorpyrifos (CPF), a broad-spectrum organophosphate insecticide, on sea urchin larvae, evaluating growth and molecular endpoints. Experimental treatments simulated future ocean conditions predicted for 2100, exposing larvae to varying temperature and pH levels, alongside CPF-contaminated MP. RNA sequencing (RNA-seq) was utilized to assess gene expression changes, revealing significant transcriptional shifts in metabolic, cellular, and developmental pathways. Morphological responses showed reduced larval growth, exacerbated under OA and OW conditions. Molecular analyses identified key upregulated pathways associated with stress response, including nitrogen metabolism and extracellular matrix remodelling, while downregulated genes involved DNA stability, cell cycle regulation, and enzymatic activities. These findings suggest a dual compensatory and deleterious response to combined stressors. Notably, temperature acted as a modulator of stressor effects, amplifying oxidative stress and metabolic costs at higher temperatures. Potential biomarkers, such as genes involved in actin regulation and embryonic development, were identified, offering possible tools for early detection of environmental stress. This study highlights the compounded impacts of anthropogenic and climate-induced stressors on marine invertebrates, emphasizing the need for integrative molecular approaches in ecotoxicology. Our findings contribute to the understanding of organismal adaptation and vulnerability in the face of global climate change and pollution, informing conservation strategies for marine ecosystems.

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Evaluating the impact of ocean acidification on seafood – a global approach

Published 23 April 2025 Science Closed
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The quality of human life and food security are closely linked to the health of the ocean and the many goods and services it provides. However, the ocean is under cumulative stress from various human-driven pressures, leading to eutrophication, deoxygenation, loss of genetic biodiversity, contamination with emerging pollutants (e.g., microplastics and pesticides), and climate change (warming and ocean acidification). The effects of multiple ocean stressors and their interplay on marine life and ecosystems remain poorly understood. This underscores the urgent need for innovative science to resolve the complexity of the interplay of stressors and the resulting impacts. This paper reports findings from the Coordinated Research Project CRP K41018, a five-year program framed by the IAEA. The project was explicitly designed to advance Member States’ understanding of both quantitative and qualitative impacts of ocean acidification on key economically relevant seafood species across different world regions. Furthermore, based on different sensitivity baselines across species, it aimed at exploring adaptation pathways for aquaculture and food industries. As a result, Member States would have improved their comprehension of resilience building in specific local contexts (e.g., types of environments, geographical parameters, human dimension). In this context, it is essential to look for ocean solutions to mitigate adverse impacts on seafood and support adaptation strategies based on nature that can counteract stressors. It is concluded that there is great synergy in planning integrated mitigation and adaptation strategies to multiple stressors in marine ecosystems.

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

Published 18 April 2025 Science Closed
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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.

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Effects of climate change on purple urchin feeding behavior in the presence and absence of California spiny lobsters

Published 11 April 2025 Science Closed
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Grazing by sea urchins can dramatically alter the structure of kelp forest communities, but this can be moderated through both direct and indirect effects from their predators. For example, in southern California, USA, the presence of spiny lobsters, Panulirus interruptus, can dramatically increase the time it takes for purple urchins, Strongylocentrotus purpuratus, to emerge from their shelters to feed, reduce the total time that the urchins spend foraging, and consequently decrease the amount of kelp they consume. The mechanisms driving this, however, may change as the oceans become warmer and more acidic. To examine this, we quantified three measures of purple urchin grazing behavior (latency to emerge from shelters, time spent feeding, and kelp mass consumed) in the presence and absence of spiny lobsters under present day (Current), ocean warming (OW), ocean acidification (OA), and OW + OA (Future) conditions. Specifically, we placed purple urchins in laboratory mesocosms reflecting these conditions with shelters and known quantities of kelp, and then allowed them to graze in both the presence and absence of lobsters for three days. Urchin feeding activity was quantified using time-lapse photography and by recording the amount of kelp eaten over each three-day period. Our results revealed that urchins took longer to emerge from their shelters, grazed for less time, and consumed less kelp when in the presence of spiny lobsters under Current conditions, but these differences largely disappeared under OW, OA and Future conditions. These results reveal possible implications for how urchins will graze when in the presence of predators and thus affect kelp forest communities in the future.

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Molecular evidence for the intermediate disturbance hypothesis in an acidified marine system

Published 25 March 2025 Science Closed
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The Intermediate Disturbance Hypothesis (IDH), postulated by Connell (1978), suggests that ecosystems exhibit higher species diversity when disturbances occur at intermediate scales. In this study, the applicability of the IDH at the intraspecific scales (organismal) was investigated using molecular data. As an experimental perturbation framework, a naturally acidified system located in La Palma Island, Canary Island (Spain) with a sharp fluctuating pH gradient was sampled. Molecular data were obtained from sequences of a fragment of the mitochondrial Cytochrome C Oxidase subunit I gene in two sea urchin species (Arbacia lixula and Paracentrotus lividus) to explore genetic diversity at the organism level. These data were compared with previous metabarcoding results of taxonomic benthic diversity at the community level. Both sea urchin species showed the highest levels of haplotype and nucleotide diversity at the intermediate pH fluctuation zone, mirroring metabarcoding data that revealed the highest levels of taxonomic diversity at the same zone. The results support the validity of the IDH in marine ecosystems affected by strong pH fluctuations and across different levels of biological organization (from organisms to communities).

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Multiple-stressor effects of ocean warming, acidification and hypoxia on the locomotor behavior of sea cucumber Apostichopus japonicus

Published 6 March 2025 Science Closed
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Highlights

  • Ocean warming, acidification, and hypoxia simultaneously affect marine organisms.
  • The combined stress significantly affects the locomotor behavior of A. japonicus.
  • The movement intensity of A. japonicus was increased under combined stressors.
  • The erratic movement patterns indicates a stress-induced escape response.

Abstract

Driven by human activities, global climate change is causing unprecedented changes in marine ecosystems, such as ocean warming, ocean acidification and hypoxia. These stressors, which often occur simultaneously and interact with each other, have significant negative impacts on marine organisms and ecosystems, and are referred to as the “deadly trio”. Understanding how these environmental stressors affect marine organisms is critical, particularly concerning their behavior and survival. Locomotion behavior, an essential aspect of an organism’s ability to find food, evade predators, and reproduce, can be significantly disrupted by environmental changes. The sea cucumber (Apostichopus japonicus), an IUCN-listed endangered species further threatened by climate change, serves as a crucial model organism for studying these effects. This study investigates the impact of combined stressors—ocean warming, acidification and hypoxia on the locomotion behavior of A. japonicus under future ocean scenarios. Cumulative movement distance, cumulative movement time, mean velocity, and maximum velocity of sea cucumbers were measured. The results show that the synergetic interaction of environmental stressors alters locomotor behavior of A. japonicus, increasing movement activity with more erratic patterns. Specifically, compared to the control group (NC), the combined stress group (WAH) showed an increase in cumulative movement time from 79.06 % to 93.40 % (P < 0.05), an increase in cumulative movement distance from 2722.11 cm to 5700.09 cm (P < 0.01), and an increase in mean velocity from 4.63 cm/s to 9.50 cm/s (P < 0.05). These findings indicate that combined stressors significantly affect the locomotion behavior of A. japonicus, providing new insights into its behavioral phenotypic adjustments or responses to environmental stress. This study emphasizes the importance of understanding the impacts of multiple-factor stressors on marine organisms to better predict and mitigate the effects of global climate change.

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Assessing benthic invertebrate vulnerability to ocean acidification and de-oxygenation in California: the importance of effective oceanographic monitoring networks

Published 21 February 2025 Science Closed
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Greenhouse gas emissions from land-use change, fossil fuel, agriculture, transportation, and electricity sectors expose marine ecosystems to overlapping environmental stressors. Existing climate vulnerability assessment methods analyze the frequency of extreme conditions but often minimally consider how environmental data gaps hinder assessments. Here, we show an approach that assesses vulnerability and the uncertainty introduced by monitoring data gaps, using a case study of ocean acidification and deoxygenation in coastal California. We employ 5 million publicly available oceanographic observations and existing studies on species responses to low pH, low oxygen conditions to calculate vulnerability for six ecologically and economically valuable benthic invertebrate species: red sea urchin (Mesocentrotus franciscanus), purple sea urchin (Strongylocentrotus purpurpatus), warty sea cucumber (Apostichopus parvimensis), pink shrimp (Pandalus jordani), California spiny lobster (Panulirus interruptus), and Dungeness crab (Metacarncinus magister). Further, we evaluate the efficacy of current monitoring programs by examining how data gaps heighten associated uncertainty. We find that most organisms experience low oxygen (<35% saturation) conditions less frequently than low pH ( < 7.6) conditions. It is only deeper dwelling (>75 m depth) life stages such as Dungeness crab adults and pink shrimp embryos, juveniles, and adults that experience more frequent exposure to low oxygen conditions. Adult Dungeness crabs experience the strongest seasonal variation in exposure. Though these trends are intriguing, exposure remains low for most species despite well-documented pH and oxygen declines and strengthening upwelling in the central portions of the California Current. Seasonal biases of data collection and sparse observations near the benthos and at depths where organisms most frequently experience stressful conditions undermine exposure estimates. Herein we provide concrete examples of how pink shrimp and Dungeness crab fisheries may be impacted by our findings, and provide suggestions for incorporating oceanographic data into management plans. By limiting our scope to California waters and assessing the limitations presented by current monitoring coverage, this study aims to provide a granular, actionable framework that policymakers and managers can build from to prioritize targeted enhancements and sustained funding of oceanographic monitoring recommendations.

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Adaptive resilience of sea urchins against seawater acidification: a study on egg quality and offspring performance within a volcanic vents area

Published 20 February 2025 Science Closed
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Highlights

  • Sea urchins were collected within and outside a volcanic carbon vents area
  • Egg quality was investigated revealing differences in size and energetic profile
  • Offspring performances were tested at 2 pH levels both with and without herbicide
  • Sea urchins from the Vents area showed better offspring performance
  • Glyphosate-AMPA mixture caused additional but limited effects compared to pH.

Abstract

Local adaptation plays a critical role in an organism’s ability to survive and reproduce in diverse environmental conditions, potentially improving an organism’s response to stressful conditions such as ocean acidification or pollution. In this study, the effects of lower pH coupled with the presence of environmental contaminants were assessed on sea urchins (Paracentrotus lividus) collected outside and inside a volcanic CO2-vent system, where the mean ambient pH is 8.1 and 7.7, respectively.

Both groups of sea urchins were spawned, and offspring were reared at pH 8.1 and 7.7, and in the presence or absence of a mixture of 100 μg/L of glyphosate and its main metabolite aminomethylphosphonic acid. Offspring performance metrics (development, abnormalities, and growth) were investigated under the different exposure conditions. The exposure to reduced pH affected the development and larval growth in echinoplutei obtained from adults of both sites, although to a different extent. Chemicals mixture had an additive effect in slowing embryo development.

Results revealed that sea urchins living within the lower pH Vents area exhibited significantly higher egg quality, which likely enhanced embryonic development, reduced abnormalities, and increased larval size compared to their counterparts outside the Vents system, both in the presence and absence of contaminants. Findings suggest that sea urchins living within the CO2-Vents system developed adaptations to thrive under lower pH conditions. Elevated egg quality and improved offspring performance suggest organisms’ resilience to environmental stressors associated with seawater acidification. Although insights gained from this study are preliminary, mostly due to the limited number of replicates in the egg biochemical analysis, they contribute to unveiling the adaptive capabilities of sea urchins in facing ongoing ocean acidification challenges.

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Effect of ocean acidification on the oxygen consumption of the sea urchins Paracentrotus lividus (Lamarck, 1816) and Arbacia lixula (Linnaeus, 1758) living in CO2 natural gradients

Published 7 February 2025 Science Closed
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Ocean acidification (OA) stands out as one of the main threats to marine ecosystems. OA leads to a reduction in the availability of carbonate ions, which are essential for marine calcifiers such as echinoderms. We aim to understand the physiological responses of two sea urchin species, Paracentrotus lividus and Arbacia lixula to low pH conditions and determine whether their responses result from phenotypic plasticity or local adaptation. The study is divided into two parts: plasticity response over time, measuring respiration rates of individuals from the Mediterranean Sea exposed to low pH over seven days, and adaptation and plasticity under changing pH, analyzing individuals inhabiting a pH gradient in a natural CO2 vent system located in La Palma Island, Spain. Over the seven days of low pH exposure, distinct patterns in respiration rates were revealed, with both species demonstrating potential for acclimatization. Notably, P. lividus and A. lixula displayed unsynchronized acidosis/alkalosis cycles, suggesting different physiological mechanisms. Additionally, environmental history seemed to influence adaptive capacity, as specimens from fluctuating pH environments exhibited respiration rates similar to those from stable environments with heightened phenotypic plasticity. Overall, our results suggest that both species possess the capacity for metabolic plasticity, which may enhance their resilience to future OA scenarios but likely involve energetic costs. Moreover, CO2 vent systems may serve as OA refugia, facilitating long-term survival. Understanding the plastic responses versus adaptations is crucial for predicting the effects of OA on species distribution and abundance of marine organisms in response to ongoing climate change.

Continue reading ‘Effect of ocean acidification on the oxygen consumption of the sea urchins Paracentrotus lividus (Lamarck, 1816) and Arbacia lixula (Linnaeus, 1758) living in CO2 natural gradients’

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

Published 22 January 2025 Science Closed
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Anthropogenic carbon dioxide emissions have been increasing rapidly in recent years, driving pH and oxygen levels to record low concentrations in the oceans. Eastern boundary upwelling systems such as the California Current System (CCS) experience exacerbated ocean acidification and hypoxia (OAH) due to the physical and chemical properties of the transported deeper waters. Research efforts have significantly increased in recent years to investigate the deleterious effects of climate change on marine species, but have not focused on the impacts of simultaneous OAH stressor exposure. Additionally, few studies have explored the physiological impacts of these environmental stressors on the earliest life stages, which are more vulnerable and represent natural population bottlenecks in organismal life cycles. The physiological response of the ecologically and commercially important red sea urchin (Mesocentrotus franciscanus) was assessed by exposing larvae to a variety of OAH conditions, mimicking the range of ecologically relevant conditions encountered currently and in the near future along the CCS. Skeleton dissolution, larval development, and gene expression show a response with clearly delineated thresholds that were related to OAH severity. Skeletal dissolution and the induction of Acid-sensing Ion Channel 1A at pH 7.94/5.70 DO mg/L provide particularly sensitive markers of OAH, with dramatic shifts in larval morphology and gene expression detected at the pH/DO transition of 7.71/3.71–7.27/2.72 mg/L. Experimental simulations that describe physiological thresholds and establish molecular markers of OAH exposure will provide fishery management with the tools to predict patterns of larval recruitment and forecast population dynamics.

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

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