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.
Continue reading ‘What doesn´t kill you makes you stronger: the sea urchin Arbacia lixula living on volcanic CO2 vents’Posts Tagged 'echinoderms'
What doesn´t kill you makes you stronger: the sea urchin Arbacia lixula living on volcanic CO2 vents
Published 1 September 2025 Science ClosedTags: adaptation, biological response, echinoderms, field, morphology, North Atlantic, otherprocess, vents
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 ClosedTags: biological response, echinoderms, fisheries, laboratory, morphology, multiple factors, North Pacific, physiology, temperature
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.
Continue reading ‘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’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 ClosedTags: biological response, echinoderms, laboratory, molecular biology, morphology, multiple factors, North Atlantic, plastics, reproduction, temperature, toxicants
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.
Continue reading ‘Molecular markers of stress in the sea urchin embryo test: analysing the effect of climate change and pollutant mixtures on Paracentrotus lividus larvae’Evaluating the impact of ocean acidification on seafood – a global approach
Published 23 April 2025 Science ClosedTags: biological response, crustaceans, echinoderms, fish, fisheries, growth, mitigation, mollusks, mortality, review
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.
Continue reading ‘Evaluating the impact of ocean acidification on seafood – a global approach’Ocean acidification research on ecologically and economically important sea cucumbers Is limited globally
Published 18 April 2025 Science ClosedTags: biological response, echinoderms, physiology, reproduction, review
Ocean acidification (OA) caused by increasing levels of partial pressure of carbon dioxide (CO2) and subsequent changes in seawater carbonate chemistry exerts knock-on effects on various calcifying organisms. However, little is known about the echinoderms (e.g., sea cucumbers) that are being overexploited globally for economic benefits. Most importantly, less is known about the impacts of OA on these organisms. Within this framework, the current study synthesized the available global data on the effects of OA on various sea cucumber species. Results indicate studies on OA impacts on sea cucumbers are limited to 10 species across eight countries globally, with Apostichopus japonicus being highly utilized under experimental conditions. Our results suggest that OA impacts reproduction, spawning events and sperm flagellar motility of sea cucumbers under low pH. This leads to the loss of energy allocations and reduction in somatic growth. Under low pH, the effects on Ca2+ and Mg2+ composition of calcareous ring and ossicles were species-specific and enzymatic activity was reduced. This study highlights the existing gaps that need to be addressed to prevent various knock-on effects of OA on sea cucumbers. This information is critical to managers and conservationists to manage the globally declining sea cucumber populations.
Continue reading ‘Ocean acidification research on ecologically and economically important sea cucumbers Is limited globally’Effects of climate change on purple urchin feeding behavior in the presence and absence of California spiny lobsters
Published 11 April 2025 Science ClosedTags: biological response, echinoderms, laboratory, multiple factors, performance, predation, temperature
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.
Continue reading ‘Effects of climate change on purple urchin feeding behavior in the presence and absence of California spiny lobsters’Molecular evidence for the intermediate disturbance hypothesis in an acidified marine system
Published 25 March 2025 Science ClosedTags: biological response, echinoderms, field, molecular biology, North Atlantic, vents
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).
Continue reading ‘Molecular evidence for the intermediate disturbance hypothesis in an acidified marine system’Multiple-stressor effects of ocean warming, acidification and hypoxia on the locomotor behavior of sea cucumber Apostichopus japonicus
Published 6 March 2025 Science ClosedTags: biological response, echinoderms, laboratory, multiple factors, North Pacific, oxygen, performance, temperature
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.
Continue reading ‘Multiple-stressor effects of ocean warming, acidification and hypoxia on the locomotor behavior of sea cucumber Apostichopus japonicus’Assessing benthic invertebrate vulnerability to ocean acidification and de-oxygenation in California: the importance of effective oceanographic monitoring networks
Published 21 February 2025 Science ClosedTags: biological response, chemistry, crustaceans, echinoderms, fisheries, methods, multiple factors, oxygen, policy, review
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.
Continue reading ‘Assessing benthic invertebrate vulnerability to ocean acidification and de-oxygenation in California: the importance of effective oceanographic monitoring networks’Adaptive resilience of sea urchins against seawater acidification: a study on egg quality and offspring performance within a volcanic vents area
Published 20 February 2025 Science ClosedTags: adaptation, biological response, echinoderms, field, multiple factors, otherprocess, reproduction, toxicants, vents
Highlights
- Sea urchins were collected within and outside a volcanic carbon vents area
- Egg quality was investigated revealing differences in size and energetic profile
- Offspring performances were tested at 2 pH levels both with and without herbicide
- Sea urchins from the Vents area showed better offspring performance
- Glyphosate-AMPA mixture caused additional but limited effects compared to pH.
Abstract
Local adaptation plays a critical role in an organism’s ability to survive and reproduce in diverse environmental conditions, potentially improving an organism’s response to stressful conditions such as ocean acidification or pollution. In this study, the effects of lower pH coupled with the presence of environmental contaminants were assessed on sea urchins (Paracentrotus lividus) collected outside and inside a volcanic CO2-vent system, where the mean ambient pH is 8.1 and 7.7, respectively.
Both groups of sea urchins were spawned, and offspring were reared at pH 8.1 and 7.7, and in the presence or absence of a mixture of 100 μg/L of glyphosate and its main metabolite aminomethylphosphonic acid. Offspring performance metrics (development, abnormalities, and growth) were investigated under the different exposure conditions. The exposure to reduced pH affected the development and larval growth in echinoplutei obtained from adults of both sites, although to a different extent. Chemicals mixture had an additive effect in slowing embryo development.
Results revealed that sea urchins living within the lower pH Vents area exhibited significantly higher egg quality, which likely enhanced embryonic development, reduced abnormalities, and increased larval size compared to their counterparts outside the Vents system, both in the presence and absence of contaminants. Findings suggest that sea urchins living within the CO2-Vents system developed adaptations to thrive under lower pH conditions. Elevated egg quality and improved offspring performance suggest organisms’ resilience to environmental stressors associated with seawater acidification. Although insights gained from this study are preliminary, mostly due to the limited number of replicates in the egg biochemical analysis, they contribute to unveiling the adaptive capabilities of sea urchins in facing ongoing ocean acidification challenges.
Continue reading ‘Adaptive resilience of sea urchins against seawater acidification: a study on egg quality and offspring performance within a volcanic vents area’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 ClosedTags: adaptation, biological response, echinoderms, field, laboratory, Mediterranean, otherprocess, physiology, respiration, vents
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 ClosedTags: biological response, dissolution, echinoderms, fisheries, molecular biology, multiple factors, North Pacific, oxygen, physiology, reproduction
Anthropogenic carbon dioxide emissions have been increasing rapidly in recent years, driving pH and oxygen levels to record low concentrations in the oceans. Eastern boundary upwelling systems such as the California Current System (CCS) experience exacerbated ocean acidification and hypoxia (OAH) due to the physical and chemical properties of the transported deeper waters. Research efforts have significantly increased in recent years to investigate the deleterious effects of climate change on marine species, but have not focused on the impacts of simultaneous OAH stressor exposure. Additionally, few studies have explored the physiological impacts of these environmental stressors on the earliest life stages, which are more vulnerable and represent natural population bottlenecks in organismal life cycles. The physiological response of the ecologically and commercially important red sea urchin (Mesocentrotus franciscanus) was assessed by exposing larvae to a variety of OAH conditions, mimicking the range of ecologically relevant conditions encountered currently and in the near future along the CCS. Skeleton dissolution, larval development, and gene expression show a response with clearly delineated thresholds that were related to OAH severity. Skeletal dissolution and the induction of Acid-sensing Ion Channel 1A at pH 7.94/5.70 DO mg/L provide particularly sensitive markers of OAH, with dramatic shifts in larval morphology and gene expression detected at the pH/DO transition of 7.71/3.71–7.27/2.72 mg/L. Experimental simulations that describe physiological thresholds and establish molecular markers of OAH exposure will provide fishery management with the tools to predict patterns of larval recruitment and forecast population dynamics.
Continue reading ‘Single-larva RNA sequencing reveals that red sea urchin larvae are vulnerable to co-occurring ocean acidification and hypoxia’Physiochemical responses of an asterinid starfish (Echinodermata: Asteroidea) to global ocean change
Published 20 January 2025 Science ClosedTags: biological response, calcification, echinoderms, laboratory, mortality, multiple factors, performance, physiology, temperature
The continuous increase in greenhouse gas (GHG) emissions, especially carbon dioxide (CO2), since the beginning of global industrialization has resulted in significant alterations in seawater physicochemical properties, particularly elevated seawater temperatures (ocean warming, OW) and ocean acidification (OA). These changes have wide-ranging consequences for marine organisms, affecting their biological functions and ecological roles. The combined effects of OW and OA may amplify adverse outcomes compared to individual stressors due to the complex reorganization of cellular mechanisms and molecular pathways, which subsequently appear in behavioral modifications. However, organismal reactions and thresholds to these stressors are variable, which might differ within organism ontogeny or among taxa, making predictions challenging. Therefore, increasing research has been performed to better understand the potential mechanisms underlying the ability of marine organisms to alleviate the effects of environmental change, mainly due to OW and OA. Thus, employing multiple bioindicators, specifically keystone species such as starfish, to evaluate the impacts of OW and OA offers a comprehensive approach to examining their effects not simply on the organism concerned but also on the broader ecosystem.
The presented studies in this thesis aim to contribute to the understanding the role of physiochemistry and trade-offs on marine ectotherms, particularly asterinid starfish, in coping with environmental stress. For this purpose, mineralogic, metabolic, behavioral, lipidomics, and enzymatic activity approaches are used. The research summarized in this thesis provides the first investigation of the effects of global ocean change on biomineralization and physiological traits through long-term experiments using asterinid starfish species, Aquilonastra yairi, distributed in tropical to subtropical regions (across the Mediterranean Sea, Red Sea, and Gulf of Suez). The starfish were exposed to two temperature levels (27 °C and 32 °C) crossed with three pCO2 regimes (455 µatm, 1052 µatm, and 2066 µatm), representing factorial combinations of ambient conditions and future levels of CO2 and temperature change according to the IPCC-Representative Concentration Pathways (RCPs) 8.5 greenhouse gas emission scenario for the year 2100.
The present work revealed that asterinid starfish demonstrate high stressor tolerance and resilience to increased temperature and pCO2 through adaptive adjustments in physiological functions or behavioral activities, suggesting high homeostatic capacities and the ability to regulate physiochemical response to maintain survival, fitness, and metabolic biosynthesis under chronic conditions. The temperature was the predominant factor, exerting a significant effect on the magnitude and frequency of the affected physiological-related processes; however, concurrent exposure to OA and OW stress produced synergistic effects on some of the starfish physiology-related responses tested. While decreased pH negatively affects starfish calcification performance, the increased temperature potentially mitigates these effects. However, increased temperature might also lead to more magnesium (Mg2+) incorporation into the calcite lattice, potentially compromising the starfish skeleton. Furthermore, it was revealed that starfish can preserve lipid-associated biochemistry (FAs) under elevated temperature and pCO2, which potentially provides molecular instruments to cope with future OA and OW scenarios. However, combined OA and OW significantly affected Ca-ATPase and Mg-ATPase enzyme activities, which are recognized to play an important role in the biomineralization pathway, raising concerns about potential susceptibilities in skeletal development and preservation.
Investigating the complex impacts of global ocean change on marine organisms requires a comprehensive research approach that encompasses diverse biological, chemical, and physical traits. Understanding the physiological and chemical responses of bioindicator species, e.g., asterinid starfish, to combined stressors OW and OA is important to comprehend the relationships and interactions between biological processes and abiotic environmental conditions, which in turn essential for accurately predicting their resilience, ecological implication, and broader ecosystem dynamics. At the ecosystem scale, this study significantly contributes to the ongoing knowledge for future studies of the impact of climate change on coral reef-associated invertebrates. Specifically, this finding is beneficial for the conservation of coral reef ecosystems under future ocean conditions.
Continue reading ‘Physiochemical responses of an asterinid starfish (Echinodermata: Asteroidea) to global ocean change’Molecular response to CO2-driven ocean acidification in the larvae of the sea urchin Hemicentrotus pulcherrimus: evidence from comparative transcriptome analyses
Published 13 January 2025 Science ClosedTags: biological response, echinoderms, laboratory, molecular biology, morphology, North Pacific, reproduction
Highlights
- Ocean acidification affects morphology of Hemicentrotus pulcherrimus larvae.
- Comparative transcriptome analyses were performed.
- Six key potential biomarkers correlated with low pH tolerance were identified.
Abstract
In order to explore the impact of CO2-driven ocean acidification (OA) on gene expression of sea urchins, gametes of Hemicentrotus pulcherrimus were fertilized and developed to the four-armed larvae in either seawater at current pH levels (pHNBS = 7.98) or in three laboratory-controlled OA conditions (ΔpHNBS = −0.3, −0.4, −0.5 units) based on the projections of the Intergovernmental Panel on Climate Change (IPCC) for 2100. Four-armed larval specimens were collected, and comparative transcriptome analysis was then performed. The results showed that 58 differentially expressed genes (DEGs) were identified in OA-treated groups as compared to the control. Moreover, more transition and transversion SNPs were observed in OA-treated groups than those in the control indicating a potential occurrence of adaption to OA in H. pulcherrimus larvae. Six candidate DEGs shared among OA-treated groups were identified as potential biomarkers correlated with low pH tolerance, mainly enriched in nine pathways associated with Notch signaling, dorso-ventral axis formation, oxidative phosphorylation, lysine degradation, valine, leucine and isoleucine degradation, lysosome, cell adhesion molecules, glutathione metabolism and PPAR signaling pathway. These results will not only enrich our knowledge of the impacts of OA on sea urchin larvae from the aspect of gene expression, provide a better understanding on larval forms coping with OA, but also offer more clues and biomarkers for developing protection or management strategies for sea urchins under near-future OA conditions.
Continue reading ‘Molecular response to CO2-driven ocean acidification in the larvae of the sea urchin Hemicentrotus pulcherrimus: evidence from comparative transcriptome analyses’Dynamic responses during early development of the sea urchin Strongylocentrotus intermedius to CO2-driven ocean acidification: a microRNA-mRNA integrated analysis
Published 9 January 2025 Science ClosedTags: biological response, echinoderms, laboratory, molecular biology, reproduction
Highlights
- Sea urchin blastula stage is the most sensitive stage to ocean acidification (OA).
- The PI3K/Akt pathway may be a hub pathway responding to OA in sea urchin larvae.
- MiR-1 may be a key regulator in the dynamic response of sea urchin larvae to OA.
Abstract
To explore the dynamic molecular responses to CO2-driven ocean acidification (OA) during the early developmental stages of sea urchins, gametes of Strongylocentrotus intermedius were fertilized and developed to the four-armed larva stage in either natural seawater (as a control; pHNBS = 7.99 ± 0.01) or acidified conditions (ΔpHNBS = −0.3, −0.4, and − 0.5 units) according to the prediction for ocean pH by the end of this century. Specimens from five developmental stages (fertilization, cleavage, blastula, prism, and four-armed larva) were collected and comparative microRNA (miRNA) and mRNA transcriptome analyses were performed. The results showed that 1) a total of 22,224 differentially expressed genes (DEGs) and 51 differentially expressed miRNAs (DEMs) were identified in the OA-treated groups compared with the control group. 2) The numbers of both DEGs and DEMs were the largest at the blastula stage, indicating dramatic changes in gene expression. 3) Five “miR-1/DEG” modules were identified as potential biomarkers reflecting the response of sea urchins to OA during the early developmental period. 4) The PI3K/Akt signaling pathway was a key pathway involved in the response of S. intermedius to OA in its early developmental stages. This study deepens our understanding of the dynamic molecular regulatory mechanisms underlying sea urchin responses to CO2-driven OA.
Continue reading ‘Dynamic responses during early development of the sea urchin Strongylocentrotus intermedius to CO2-driven ocean acidification: a microRNA-mRNA integrated analysis’Genomic signals of adaptation to a natural CO2 gradient over a striking microgeographic scale
Published 14 November 2024 Science ClosedTags: adaptation, biological response, calcification, echinoderms, growth, laboratory, molecular biology, North Atlantic, otherprocess, physiology, vents
Highlights
- Arbacia lixula populations near CO2 vents show tolerance to acidification despite their vulnerable calcified structure.
- A. lixula population reveal genetic divergence and substructure in response to small-scale pH variation.
- Acidification potentially affects specific genes linked to growth, development, and calcification.
- lixula exhibits adaptability and plasticity to acidification, suggesting its potential resilience to cope with OA.
Abstract
Our study explores genomic signs of adaptation in A. lixula to different water pH conditions. To achieve this, we analysed the genomics variation of A. lixula individuals living across a natural pH gradient in Canary Islands, Spain. We use a 2b-RADseq protocol with 74 samples from sites with varying pH levels (from 7.3 to 7.9 during low tide) and included a control site. We identified 14,883 SNPs, with 432 identified as candidate SNPs under selection to pH variations through redundancy analysis. While all SNPs indicated genomic homogeneity, the 432 candidate SNPs under selection displayed genomic differences among sites and along the pH gradient. Out of these 432 loci, 17 were annotated using published A. lixula transcriptomes, involved in biological functions such as growth. Therefore, our findings suggest local adaptation in A. lixula populations to acidification in CO2 vents, even over short distances of 75 m, underscoring their potential resistance to future Ocean Acidification.
Continue reading ‘Genomic signals of adaptation to a natural CO2 gradient over a striking microgeographic scale’Drivers of biological diversity and responses to global changes in marine invertebrates
Published 12 November 2024 Science ClosedTags: adaptation, biological response, BRcommunity, community composition, corals, echinoderms, Indian, laboratory, molecular biology, otherprocess, reproduction
Human activities, in particular global changes (e.g., ocean warming – OW and ocean acidification – OA) are projected to drive some marine species to extinction within the coming decades. Marine invertebrates are amongst the most vulnerable to these changes due to the increased energetic cost to maintain intracellular pH homeostasis. To mitigate extinction, organisms may migrate, acclimate or adapt genetically. While these mechanisms are increasingly documented, they are not fully understood. This knowledge is critical for assessment of extinction risks, an important index for effective conservation and management of marine biodiversity. This thesis aims to increase our understanding on the drivers of biological diversity and sensitivity of marine invertebrates to OW and OA. Specifically, I assess (1) the quality of inferences on adaptive evolution in recent publications on responses of marine invertebrates to OW or OA and summarize the current knowledge and identify the gaps (Paper I); (2) the drivers of genetic diversity, structure, connectivity among Acropora austera populations across Mozambique coral reefs (Paper II); (3) the sensitivity to low pH in larvae of the sea urchin, Tripneustes gratilla, from subtidal and intertidal seagrass meadows with contrasting pH variability at Inhaca Island, Mozambique (Paper III); (4) the role of natural fluctuation in pH on the response of larvae of the sea urchin Echinus esculentus to low pH (Paper IV). Field genome scans surveys, laboratory experiments and systematic literature review were used. My systematic literature review (Paper I) highlights that publication on adaptive responses of marine invertebrates to OW or OA used more frequently strong methods for inferences of genetic change, such as common garden experiments and molecular genetic analysis. Methods for weaker inferences, such as comparison to model prediction, were less frequently used. On the other hand, reciprocal transplants, the stronger method for inferring adaptive change was less used in comparison with weaker methods such as phenotypic and genotypic selection. I also showed different levels of genetic variability and connectivity between populations of corals along the Mozambique coast. These geographic differences in levels of genetic diversity and connectivity may be explained by oceanographic factors and mode of reproduction of the corals (Paper II). Larvae of the sea urchin T. gratilla from Inhaca Island had reduced fitness when exposed to low pH. Moreover, larvae from adults collected in an intertidal habitat were more sensitive to low pH as compared to larvae from adults collected in a subtidal population. This result reveals population specific responses to low pH and challenges current theories that predict higher tolerance in individuals living in habitats with higher pH range (Paper III). Under present day natural variability in pH, the extreme low pH does not appear to be the main driver of biological responses in larvae of the sea urchin E. esculentus and adaptation to such conditions might be associated with a cost of plasticity but not a cost of canalization (Paper IV). Overall, this thesis shows that oceanographic factors and natural variability in pH influence the levels of genetic diversity and biological sensitivity in populations of marine invertebrates. These parameters should be considered to better evaluate the ability of marine invertebrates to withstand environmental changes and to sustain the provision of ecological functions, and guide conservation strategies.
Continue reading ‘Drivers of biological diversity and responses to global changes in marine invertebrates’Benthic diatom response to short-term acidification and warming influenced by grazing and nutrients
Published 7 October 2024 Science ClosedTags: biological response, BRcommunity, community composition, echinoderms, laboratory, mollusks, multiple factors, otherprocess, physiology, phytoplankton, temperature
Highlights
- Periphyton was not affected by acidification and warming as nutrients are replete.
- Direct effects of acidification and warming on grazers indirectly affected periphyton.
- Differences in fecal production of grazers affected rate of periphyton regeneration.
- Complex multiple factor interactions are important considerations for future studies.
Abstract
This study investigated differences in total biomass (ash-free dry weight) of the periphyton and autotrophic biomass (chlorophyll-a content) of benthic diatoms in the absence or presence (No Grazer vs With Grazer) of two invertebrate grazers (Stichopus cf. horrens and Trochus maculatus) under simulated ambient (PRESENT), independent ocean acidification (OA) and warming (OW), and their combination (FUTURE) over an eight-day period. In the absence of a grazer, there were no significant differences in the average of the total and autotrophic biomass among treatments for both experiments. Stichopus significantly reduced the total and autotrophic biomass after 1 day, except under OW. Trochus significantly reduced the total biomass in the OA and OW treatments after 5 days, and the autotrophic biomass in the OA treatment after 1 and 5 days of grazing. In treatments where total and autotrophic biomass were not reduced, nutrients from the fecal matter and metabolic wastes of grazers seemingly stimulated the regeneration of microalgal biomass. The amount of fecal matter produced also affected the rate of microalgal renewal. In addition, due to the unexpected difference in seawater nutrient concentration during the two experiments, comparison of primary production under PRESENT was done to tease out nutrient effects. In PRESENT, autotrophic biomass was higher in Experiment 1 than Experiment 2, which was likely influenced by differences in nutrient concentrations. Results of this study elucidate underlying mechanisms in microalgal interactions with biotic and abiotic factors in tropical systems under changing ocean conditions.
Continue reading ‘Benthic diatom response to short-term acidification and warming influenced by grazing and nutrients’Skeletal magnesium content in Antarctic echinoderms along a latitudinal gradient
Published 4 October 2024 Science ClosedTags: Antarctic, biological response, BRcommunity, calcification, community composition, echinoderms, laboratory, otherprocess, physiology, respiration
Highlights
- Skeletal structures presented high Mg content, except in echinoid spines.
- Asteroids had the highest Mg content, followed by ophiuroids, holothuroids, and echinoids.
- No local variability in skeletal Mg content was observed in asteroids and holothuroids.
- Environmental parameters may have influenced the skeletal Mg in ophiuroids and echinoids.
Abstract
Ocean warming and acidification driven by anthropogenic CO2 emissions may impact the mineral composition of marine calcifiers. Species with high skeletal Mg content could be more susceptible in polar regions due to the increased solubility of CO2 at lower temperatures. We aimed to assess the environmental influence on skeletal Mg content of Antarctic echinoderms belonging to Asteroidea, Ophiuroidea, Echinoidea and Holothuroidea classes, along a latitudinal gradient from the South Shetland Islands to Rothera (Adelaide Island). We found that all skeletal structures, except for echinoid spines, exhibited high Mg content, with asteroids showing the highest levels. Our results suggest that asteroids and holothuroids exert a higher biological capacity to regulate Mg incorporation into their skeletons. In contrast, the variability observed in the skeletal Mg content of ophiuroids and echinoids appears to be more influenced by local environmental conditions. Species-specific differences in how environmental factors affect the skeletal Mg content can thus be expected as a response to global climate change.
Continue reading ‘Skeletal magnesium content in Antarctic echinoderms along a latitudinal gradient’Long-term study of the combined effects of ocean acidification and warming on the mottled brittle star Ophionereis fasciata
Published 27 September 2024 Science ClosedTags: biological response, BRcommunity, calcification, dissolution, echinoderms, growth, mesocosms, mortality, multiple factors, physiology, respiration, temperature
The global ocean is rapidly changing, posing a substantial threat to the viability of marine populations due to the co-occurrence of multiple drivers, such as ocean warming (OW) and ocean acidification (OA). To persist, marine species must undergo some combination of acclimation and adaptation in response to these changes. Understanding such responses is essential to measure and project the magnitude and direction of current and future vulnerabilities in marine ecosystems. Echinoderms have been recognised as a model in studying of OW-OA effects on marine biota. However, despite their global diversity, vulnerability, and ecological importance in most marine habitats, brittle stars (ophiuroids) are poorly studied. A long-term mesocosm experiment was conducted on adult mottled brittle star (Ophionereis fasciata) as a case study to investigate the physiological response and trade-offs of marine organisms to ocean acidification, ocean warming and the combined effect of both drivers. Long-term exposure of O. fasciata to high temperature and low pH affected survival, respiration and regeneration rates, growth rate, calcification/dissolution, and righting response. Higher temperatures increased stress and respiration and decreased regeneration and growth rates as well as survival. Conversely, changes in pH had more subtle or no effect affecting only respiration and calcification. Our results indicate that exposure to a combination of high temperature and low pH produces complex responses for respiration, righting response and calcification. We address the knowledge gap of the impact of a changing ocean on ophiuroids in the context of echinoderm studies, proposing this class as an ideal alternative echinoderm for future research.
Continue reading ‘Long-term study of the combined effects of ocean acidification and warming on the mottled brittle star Ophionereis fasciata’
