Ocean acidification and warming could affect animal physiology, key trophic interactions and ecosystem functioning in the long term. This study investigates the effects of four pH−temperature combination treatments simulating ocean acidification (OA), ocean warming (OW) and combined OA and OW conditions (FUTURE) relative to ambient present-day conditions (PRESENT) on the grazing of the juveniles of two seagrass-associated invertebrates namely the sea cucumber Stichopus cf. horrens and topshell Trochus maculatus over a 5-day exposure period. Diel and feeding activity of both species increased under OW and FUTURE to some extent, while the nighttime activity of Trochus but not Stichopus decreased under OA relative to PRESENT during the first 2 days. Fecal production of Stichopus did not differ among treatments, while the lowest fecal production of Trochus was observed under OA during the first 24 h of grazing. These responses suggest that Trochus may be initially more sensitive to OA compared with Stichopus. Interestingly, fecal production of Trochus in FUTURE was significantly higher than OA, suggesting that warming may ameliorate the negative effect of acidification. Diel activity, feeding and fecal production after 5 days did not differ among treatments for both species, suggesting acclimation to the acute changes in temperature and pH after a few days, although Stichopus acclimated rapidly than Trochus. The ability of the two juvenile invertebrate grazers to rapidly acclimate to increased temperature and lowered pH conditions after short-term exposure may favor their survival under projected changes in ocean conditions.
Continue reading ‘Short-term exposure to independent and combined acidification and warming elicits differential responses from two tropical seagrass-associated invertebrate grazers’Posts Tagged 'echinoderms'
Short-term exposure to independent and combined acidification and warming elicits differential responses from two tropical seagrass-associated invertebrate grazers
Published 18 August 2023 Science ClosedTags: biological response, echinoderms, laboratory, mollusks, multiple factors, performance, physiology, South Pacific, temperature
Estuarine shellfish and climate change
Published 14 August 2023 Science ClosedTags: biological response, crustaceans, echinoderms, mollusks, review
Over centuries, shellfish populations have directly and indirectly benefitted humans living in coastal communities by providing fisheries and ecosystem services. The naturally dynamic estuarine environment, home to many economically important shellfish populations is, however, also commonly subjected to anthropogenic pressure from exploitation, pollution, and the acceleration of climate change. Climate change alters the rate and direction of long-term biogeochemical change in the ocean, but also, in combination with large-scale climate oscillations and other factors, can modulate the frequency, persistence, and/or magnitude of extreme coastal events including estuarine heatwaves, coastal hypoxia, and coastal acidification. This chapter explores the dynamic variability of the estuarine environment and assesses the impacts of climate stressors in isolation and in combination with other climatic/anthropogenic stressors on estuarine shellfish species. Individually, warming temperatures can alter the rates of physiological processes and can result in changes in growth and reproduction, while extremes in temperature can elicit physiological stress, mortality, or even local extinctions. Range contractions or expansions resulting from shifts in temperature or salinity can have cascading effects on ecosystem functioning, as important functional roles associated with shellfish (i.e., suspension-feeding, habitat engineering, bioturbation, predation) are gained or lost. Since nearly all shellfish species produce calcified structures exposed to the external environment, increasing CO2 concentrations and extremes in CO2 can have negative consequences on calcification that may vary by life stage and may have fitness-related consequences. Low oxygen extremes, which may become more persistent or severe under warming temperatures, consistently yield negative effects on the growth, development, metabolism, reproduction, survival, and/or abundance of mollusks and crustaceans and, thus, can have disproportionate impacts on ecosystem functioning.Estuaries commonly host co-occurring extremes (e.g., hypoxia and acidification), forcing organisms to cope with multiple stressors. Multi-stressors, an emerging field of research, can have a range of additive, synergistic, and antagonistic effects on shellfish species, with additional stressors typically yielding more negative outcomes than single stressors. Still, there are many unknowns regarding the potential effects of climate change syndromes on coastal shellfish, particularly in dynamic estuarine environments, and examinations of the combined impacts of warming/hypoxia/acidification and/or harmful algal blooms have only just begun. Autonomous observing platforms and high-frequency sensor arrays are essential to generating long-term and fine-scale time series datasets to characterize the shifting biogeochemical patterns under climate change. It will also be critical to scale up physiological studies to assess impacts on populations, communities, and ecosystems. Finally, to protect and/or restore shellfish resources, continued collaboration between communities and researchers on adaptive strategies that mitigate harm to shellfish populations experiencing extremes in future change will be vital.
Continue reading ‘Estuarine shellfish and climate change’Responses of marine macroalgae to climate change drivers
Published 11 August 2023 Science ClosedTags: biological response, crustaceans, echinoderms, mollusks, review
Climate changes are progressively altering global ocean environments, leading to ocean acidification and warming, marine heatwaves, deoxygenation, and enhanced exposure of UV radiations within upper mixing layers. Marine macroalgae are affected by these environmental changes in coastal waters, where changing magnitudes of these drivers are usually larger than in open oceans. While macroalgae have developed physiological mechanisms to cope with these stressors, their responses to or tolerances to these stressors are species-specific and spatiotemporally variable. Fleshy macroalgal species are commonly capable of tolerating moderate decline of pH and diel fluctuations of pH, and their growth and photosynthesis can be enhanced by elevated CO2 concentrations in seawater and in the air during emersion at low tides. However, macroalgal calcifiers are especially sensitive to ocean acidification, with their calcification being reduced, which exacerbates the harm of solar UV radiation due to thinned protective calcareous layers. Marine warming and heatwaves, however, may endanger most macroalgal species as their seasonality of life cycle is temperature-dependent. Macroalgae either distributed in upper or lower intertidal zones are susceptible to UV radiation, which may have negative, neutral, or beneficial effects on them, depending on the levels of UV and other factors. UV-A (315–400 nm) can stimulate the photosynthesis of macroalgae under low to moderate levels of solar radiation; however, UV-B (280–315 nm) mainly causes negative effects. While the combined effects of elevated temperature, CO2, and UV radiation have rarely been documented, exposures to marine heatwaves and high levels of UV can be fatal to microscopic stages of macroalgae. Apart from the species found in estuaries, the physiology and community structure of macroalgae can be influenced by reduced salinity and pH associated with rainfall and/or terrestrial runoffs. Nevertheless, reduced O2 availability associated with ocean deoxygenation and/or hypoxia, promoted by eutrophication and ocean warming, may favor macroalgal carbon fixation because of suppressed photorespiration due to reduced O2 vs. CO2 ratios, although little documentation exists to support this possibility. While macroscopic stages of macroalgae are resilient or even benefit from some of the drivers, their microscopic stages and/or juveniles are susceptible to ocean climate changes, and the sustainability of their life cycles is endangered. In this chapter, we review and analyze the responses of different macroalgal groups and different life cycle stages to climate change drivers individually and/or jointly based on the literature surveyed, along with perspectives for future studies on the multifaceted effects of ocean climate changes.
Continue reading ‘Responses of marine macroalgae to climate change drivers’The effects of ocean change drivers on the ecophysiology of the mottled brittle star Ophionereis fasciata
Published 18 July 2023 Science ClosedTags: biological response, calcification, dissolution, echinoderms, growth, laboratory, mesocosms, mortality, multiple factors, performance, physiology, South Pacific, temperature
Global ocean environments are rapidly changing, posing a substantial threat to the viability of marine populations due to the co-occurrence of different changing ocean (CO) drivers, such as ocean warming (OW) and ocean acidification (OA). In order to persist, marine species undergo some combination of acclimation and adaptation in response to these changes. Understanding such responses is essential to measure and predict the magnitude and direction of environmental changes, leading to the development of different approaches to understanding the links and interactions between biological processes and abiotic environmental conditions. A series of long-term mesocosm experiments have been conducted using adult Ophionereis fasciata as a model to investigate the physiological response and trade-offs of marine organisms to ocean acidification, ocean warming and the combined effect of both drivers. A scenario-based approach was adopted to elucidate the primary physiological responses to conditions currently experienced by this species in its tidally influenced habitat (21-24°C and pH 7.75-7.4) as well as changes expected to occur in the near future due to CO (+2.5 ℃ and -0.36 pH by 2100). Long-term exposure to OW and OA conditions affected survival, metabolic rate, regeneration and growth rates, calcification/dissolution and the righting response of O. fasciata. Temperature changes clearly impacted these aspects of the mottled brittle star, while changes in pH had more subtle or no effect. Our results indicate that for most of the assessed ecophysiological traits, there are no significant interactive effects of OA and OW. Moreover, temperature was the dominant driver, with a greater impact regarding the magnitude and quantity of the affected processes. However, the exposure to a combination of high temperature and low pH produced complex responses in terms of survival and calcification/dissolution. Finally, we documented the first report of symbionts associated with O. fasciata: an obligate amphipod parasite and a facultative commensal polychaete. Our findings indicate that the mottled brittle star will need to cope with CO conditions in context with the predictions made for New Zealand waters, with a potential impact on its performance and survival, as well as its distribution and ecological interactions.
Continue reading ‘The effects of ocean change drivers on the ecophysiology of the mottled brittle star Ophionereis fasciata’Increased sensitivity of sea urchin larvae to metal toxicity as a consequence of the past two decades of climate change and ocean acidification in the Mediterranean Sea
Published 14 July 2023 Science ClosedTags: biological response, echinoderms, field, Mediterranean, physiology
Highlights
- Climate change and ocean acidification affect reproductive health of sea urchins.
- Larvae ability to cope with copper deteriorated in the past 20 years.
- Contribution of CO2, pH and temperature worsened in the past 7 years.
Abstract
The Mediterranean Sea represents a natural laboratory to infer the possible impacts of climate change and ocean acidification. In this article, we report the deteriorating ability of sea urchin larvae (Paracentrotus lividus) to cope with toxicity of a reference contaminant (Cu EC50) over the past 20 years and assessed the influence of 5 environmental factors from satellite measurements. This timeframe was divided in before and after January 2016 (46.57 μg/L vs 28.56 μg/L respectively, p < 0.001). In the second subset of data, correlation of the biological variable with CO2 and pH strengthened compared to the first part (rCO2-EC50: −0.21 vs −0.83 and rpH-EC50: 0.25 vs 0.87 respectively), with a causal link starting from one year and ending 4 months prior to EC50 measurements. Considering the continuous increase in CO2 concentrations recorded recently, this study could reveal a rapid deterioration of the health condition of this population of sea urchins in a coastal ecosystem.
Continue reading ‘Increased sensitivity of sea urchin larvae to metal toxicity as a consequence of the past two decades of climate change and ocean acidification in the Mediterranean Sea’Surviving in an acidifying ocean: acid-base physiology and energetics of the sea urchin larva
Published 13 July 2023 Science ClosedTags: biological response, echinoderms, physiology, review
The sea urchin larva has been used by biologists for more than a century to study the development and evolution of animals. Surprisingly, very little information has been generated regarding the physiology of this small planktonic organism. However, in the context of anthropogenic CO2-driven ocean acidification (OA), the membrane transport physiology and energetics of this marine model organism have received considerable attention in the past decade. This has led to the discovery of new, exciting physiological systems, including a highly alkaline digestive tract and the calcifying primary mesenchyme cells that generate the larval skeleton. These physiological systems directly relate to the energetics of the organisms when challenged by OA. Here we review the latest membrane transport physiology and energetics in the sea urchin larva, we identify emerging questions, and we point to important future directions in the field of marine physiology in times of rapid climate change.
Continue reading ‘Surviving in an acidifying ocean: acid-base physiology and energetics of the sea urchin larva’Variable food alters responses of larval crown-of-thorns starfish to ocean warming but not acidification
Published 20 June 2023 Science ClosedTags: biological response, echinoderms, laboratory, morphology, mortality, multiple factors, nutrients, performance, South Pacific, temperature
Phytoplankton abundance is decreasing and becoming more variable as the ocean climate changes. We examine how low, high, and variable phytoplankton food supply affected the survival, development, and growth of larval crown-of-thorns starfish, Acanthaster sp. exposed to combined warming (26, 30 °C) and acidification (pH 8.0, 7.6). Larvae fed a low food ration are smaller, and develop slower and with more abnormalities than larvae fed a high ration. Larvae fed a variable food supply (low, followed by high ration) overcome the negative effects of low food on development rate and occurrence of abnormalities, but are 16–17% smaller than larvae fed the high ration continuously. Acidification (pH 7.6) slows growth and development and increases abnormalities regardless of the food regime. Warming slows growth and development, but these effects are mitigated by high food availability. As tropical oceans warm, the success of crown-of-thorns starfish larvae may depend on the abundance of their phytoplankton prey.
Continue reading ‘Variable food alters responses of larval crown-of-thorns starfish to ocean warming but not acidification’Global climate change increases the impact of pollutant mixtures in the model species Paracentrotus lividus
Published 20 June 2023 Science ClosedTags: biological response, echinoderms, laboratory, morphology, multiple factors, North Atlantic, reproduction, temperature, toxicants
Highlights
- Impact of chlorpyrifos (CPF) and microplastics (MP) on P. lividus is studied.
- We also studied if climate change increases the toxicity of these pollutants.
- CPF has a marked effect on growth of larvae, but less on the fertilisation rate.
- MP increases the negative effect of CPF on growth and development.
- Global climate change conditions increase the sensitivity of embryos to MP and CPF.
Abstract
The goal of the present work is to study whether ocean- acidification (OA) and -warming (OW) could increase the toxicity of pollutants on P. lividus. We studied how model pollutants such as chlorpyrifos (CPF) and microplastics (MP), alone or in combination, impact the fertilisation process, and the development of larvae under conditions of OA (dissolved inorganic carbon increase of 126 × 10−6 mol per kg of sea water) and OW (temperature increase of 4 °C) predicted by FAO (Food and Agriculture Organization) for the next 50 years. Fertilisation was determined by microscopic examination after 1 h. Growth, morphology, and alteration level were measured after 48 h of incubation. Results showed that CPF has a marked effect on the growth of larvae, but less on the fertilisation rate. When larvae are exposed to both MP and CPF, the effect on fertilisation and growth is higher than when CPF is added alone. Larvae exposed to CPF tend to adopt a rounded shape which is detrimental to their buoyancy and the combination with other stressors aggravate this situation. The variables most influenced by CPF or its mixtures are those related to body length, body width, and higher levels of body abnormalities, which is consistent with the degenerative effects caused by CPF on sea urchin larvae. The PCA analysis showed that temperature has more influence when embryos or larvae are exposed to a combination of stressors, demonstrating that global climate change drastically increase the impact of CPF on aquatic ecosystems. Overall, in this work we demonstrated that global climate change conditions increase the sensitivity of embryos to MP and CPF. Our findings support the idea that global change conditions could have a severe impact on marine life, increasing the negative effect of toxic agents commonly present in the sea and their mixtures.
Continue reading ‘Global climate change increases the impact of pollutant mixtures in the model species Paracentrotus lividus’Risk assessment of a coastal ecosystem from SW Spain exposed to CO2 enrichment conditions
Published 8 June 2023 Science ClosedTags: abundance, biogeochemistry, biological response, BRcommunity, community composition, crustaceans, echinoderms, laboratory, mesocosms, mollusks, morphology, mortality, North Atlantic, otherprocess, physiology, sediment
The Weight-of-Evidence (WOE) approach uses multiple lines of evidence to analyze the adverse effects associated with CO2 enrichment in two stations from the Gulf of Cádiz (Spain) with different contamination degrees. Sediment contamination and metal (loid) mobility, toxicity, ecological integrity, and bioaccumulation from the samples exposed to different acidification scenarios (pH gradient from 8.0 to 6.0) were used in the WOE. The experiments were conducted under laboratory conditions using a CO2-bubbling system. Different integration approaches such as multivariate analyses were used to evaluate the results. The results indicated that the adverse biological effects under pH 6.5 were related to the mobility of dissolved elements (As, Fe, Cu, Ni, and Zn). Furthermore, the pH reduction was correlated to the increase of bioaccumulation of As, Cr, Cu, Fe, and Ni in the tissues of mussels at pH 7.0. The noncontaminated sediment showed environmental degradation related to the acidification at pH values of 7.0; whereas the sediment moderately contaminated showed both environmental risks, caused by acidification and the presence and the increase of the bioavailability of contaminants. The WOE approach supposes an effective tool to identify and distinguish the causes of adverse effects related to the enrichment of CO2 in marine environments.
Continue reading ‘Risk assessment of a coastal ecosystem from SW Spain exposed to CO2 enrichment conditions’Marine macroinvertebrate ecosystem services under changing conditions of seagrasses and mangroves
Published 5 June 2023 Science ClosedTags: abundance, annelids, biological response, BRcommunity, chemistry, cnidaria, community composition, crustaceans, echinoderms, Indian, mollusks, otherprocess, phanerogams, phytoplankton, primary production, review, socio-economy
Highlights
- Overfishing and climate change show potential effects on MMI ES.
- MMI regulating ES can be quantified using species richness and functional traits.
- Digital platforms are valuable tools to retrieve data but have limitations.
- Baseline data and information on environmental changes and MMI ES is provided.
Abstract
This study aimed to investigate the impact of changing environmental conditions on MMI ES in seagrasses and mangroves. We used data from satellite and biodiversity platforms combined with field data to explore the links between ecosystem pressures (habitat conversion, overexploitation, climate change), conditions (environmental quality, ecosystem attributes), and MMI ES (provisioning, regulation, cultural). Both seagrass and mangrove extents increased significantly since 2016. While sea surface temperature showed no significant annual variation, sea surface partial pressure CO2, height above sea level and pH presented significant changes. Among the environmental quality variables only silicate, PO4 and phytoplankton showed significant annual varying trends. The MMI food provisioning increased significantly, indicating overexploitation that needs urgent attention. MMI regulation and cultural ES did not show significant trends overtime. Our results show that MMI ES are affected by multiple factors and their interactions can be complex and non-linear. We identified key research gaps and suggested future directions for research. We also provided relevant data that can support future ES assessments.
Continue reading ‘Marine macroinvertebrate ecosystem services under changing conditions of seagrasses and mangroves’Long-term physiological responses to combined ocean acidification and warming show energetic trade-offs in an asterinid starfish
Published 22 May 2023 Science ClosedTags: biological response, calcification, echinoderms, laboratory, mortality, multiple factors, North Atlantic, performance, physiology, temperature
While organismal responses to climate change and ocean acidification are increasingly documented, longer-term (> a few weeks) experiments with marine organisms are still sparse. However, such experiments are crucial for assessing potential acclimatization mechanisms, as well as predicting species-specific responses to environmental change. Here, we assess the combined effects of elevated pCO2 and temperature on organismal metabolism, mortality, righting activity, and calcification of the coral reef-associated starfish Aquilonastra yairi. Specimens were incubated at two temperature levels (27 °C and 32 °C) crossed with three pCO2 regimes (455 µatm, 1052 µatm, and 2066 µatm) for 90 days. At the end of the experiment, mortality was not altered by temperature and pCO2 treatments. Elevated temperature alone increased metabolic rate, accelerated righting activity, and caused a decline in calcification rate, while high pCO2 increased metabolic rate and reduced calcification rate, but did not affect the righting activity. We document that temperature is the main stressor regulating starfish physiology. However, the combination of high temperature and high pCO2 showed nonlinear and potentially synergistic effects on organismal physiology (e.g., metabolic rate), where the elevated temperature allowed the starfish to better cope with the adverse effect of high pCO2 concentration (low pH) on calcification and reduced skeletal dissolution (antagonistic interactive effects) interpreted as a result of energetic trade-offs.
Continue reading ‘Long-term physiological responses to combined ocean acidification and warming show energetic trade-offs in an asterinid starfish’Acid times in physiology: a systematic review of the effects of ocean acidification on calcifying invertebrates
Published 5 May 2023 Science ClosedTags: biological response, calcification, corals, crustaceans, echinoderms, growth, mollusks, mortality, physiology, review
The reduction in seawater pH from rising levels of carbon dioxide (CO2) in the oceans has been recognized as an important force shaping the future of marine ecosystems. Therefore, numerous studies have reported the effects of ocean acidification (OA) in different compartments of important animal groups, based on field and/or laboratory observations. Calcifying invertebrates have received considerable attention in recent years. In the present systematic review, we have summarized the physiological responses to OA in coral, echinoderm, mollusk, and crustacean species exposed to predicted ocean acidification conditions in the near future. The Scopus, Web of Science, and PubMed databases were used for the literature search, and 75 articles were obtained based on the inclusion criteria. Six main physiological responses have been reported after exposure to low pH. Growth (21.6%), metabolism (20.8%), and acid-base balance (17.6%) were the most frequent among the phyla, while calcification and growth were the physiological responses most affected by OA (>40%). Studies show that the reduction of pH in the aquatic environment, in general, supports the maintenance of metabolic parameters in invertebrates, with redistribution of energy to biological functions, generating limitations to calcification, which can have severe consequences for the health and survival of these organisms. It should be noted that the OA results are variable, with inter and/or intraspecific differences. In summary, this systematic review offers important scientific evidence for establishing paradigms in the physiology of climate change in addition to gathering valuable information on the subject and future research perspectives.
Continue reading ‘Acid times in physiology: a systematic review of the effects of ocean acidification on calcifying invertebrates’How ocean warming and acidification affect the life cycle of six worldwide commercialised sea urchin species: a review
Published 19 April 2023 Science ClosedTags: abundance, adaptation, Arctic, biological response, echinoderms, Mediterranean, morphology, mortality, multiple factors, North Pacific, otherprocess, performance, physiology, reproduction, review, South Pacific, temperature
Ongoing global changes are expected to affect the worldwide production of many fisheries and aquaculture systems. Because invertebrates represent a relevant industry, it is crucial to anticipate challenges that are resulting from the current environmental alterations. In this review, we rely on the estimated physiological limits of six commercialised species of sea urchins (Loxechinus albus, Mesocentrotus franciscanus, Paracentrotus lividus, Strongylocentrotus droebachiensis, Strongylocentrotus intermedius and Strongylocentrotus purpuratus) to define the vulnerability (or resilience) of their populations facing ocean warming and acidification (OW&A). Considering that coastal systems do not change uniformly and that the populations’ response to stressors varies depending on their origin, we investigate the effects of OW&A by including studies that estimate future environmental mutations within their distribution areas. Cross-referencing 79 studies, we find that several sea urchin populations are potentially vulnerable to the predicted OW&A as environmental conditions in certain regions are expected to shift beyond their estimated physiological limit of tolerance. Specifically, while upper thermal thresholds seem to be respected for L. albus along the SW American coast, M. franciscanus and S. purpuratus southern populations appear to be vulnerable in NW America. Moreover, as a result of the strong warming expected in the Arctic and sub-Arctic regions, the local productivity of S. droebachiensis is also potentially largely affected. Finally, populations of S. intermedius and P. lividus found in northern Japan and eastern Mediterranean respectively, are supposed to decline due to large environmental changes brought about by OW&A. This review highlights the status and the potential of local adaptation of a number of sea urchin populations in response to changing environmental conditions, revealing possible future challenges for various local fishing industries.
Continue reading ‘How ocean warming and acidification affect the life cycle of six worldwide commercialised sea urchin species: a review’Thanks mum. Maternal effects in response to ocean acidification of sea urchin larvae at different ecologically relevant temperatures
Published 3 March 2023 Science ClosedTags: biological response, echinoderms, Mediterranean, morphology, multiple factors, reproduction, temperature, vents
Highlights
- Ocean acidification and temperature differently influence larval development of Arbacia lixula and Paracentrotus lividus.
- Larvae of the two A. lixula populations (ambient-pH vs vent sites) respond differently to ocean acidification and temperature.
- Maternal buffer effect was observed in response to ocean acidification and temperature in both species.
- A. lixula seems to be more tolerant to changes in temperature than P. lividus.
Abstract
Juvenile stages of marine species might be more vulnerable than adults to climate change, however larval vulnerability to predictable environmental changes can be mitigated by parental anticipatory buffer effects occurring during gametogenesis. In this study, ocean acidification effect were investigated on larval growth of two sea urchins, Arbacia lixula and Paracentrotus lividus, at different temperature levels. Results showed that altered pH and temperature affected larval development in both species, with significant length reductions of spicules and significant increases in abnormal larvae. Detrimental effects of reduced pH and high temperature were however dependent on the mother. Furthermore, the responses of A. lixula larvae from the ambient site (pH ∼ 8.0) were compared with those of larvae obtained from mothers collected from a natural CO2 vent (pH ∼ 7.7) in Ischia. Comparisons highlighted a transgenerational response, as the CO2 vent larvae proved to be more resilient to reduced pH, although more sensitive to increased temperature.
Continue reading ‘Thanks mum. Maternal effects in response to ocean acidification of sea urchin larvae at different ecologically relevant temperatures’Common sea star (Asterias rubens) coelomic fluid changes in response to short-term exposure to environmental stressors
Published 2 March 2023 Science ClosedTags: biological response, echinoderms, laboratory, multiple factors, North Atlantic, oxygen, physiology, temperature
Common sea stars (Asterias rubens) are at risk of physiological stress and decline with projected shifts in oceanic conditions. This study assessed changes in coelomic fluid (CF) blood gases, electrolytes, osmolality, and coelomocyte counts in adult common sea stars after exposure to stressors mimicking effects from climate change for 14 days, including decreased pH (−0.4 units, mean: 7.37), hypoxia (target dissolved oxygen ~1.75 mg O2/L, mean: 1.80 mg O2/L), or increased temperature (+10 °C, mean: 17.2 °C) and compared sea star CF electrolytes and osmolality to tank water. Changes in CF blood gases, electrolytes, and/or coelomocyte counts occurred in all treatment groups after stressor exposures, indicating adverse systemic effects with evidence of increased energy expenditure, respiratory or metabolic derangements, and immunosuppression or inflammation. At baseline, CF potassium and osmolality of all groups combined were significantly higher than tank water, and, after exposures, CF potassium was significantly higher in the hypoxia group as compared to tank water. These findings indicate physiological challenges for A. rubens after stressor exposures and, given increased observations of sea star wasting events globally, this provides evidence that sea stars as a broad group are particularly vulnerable to changing oceans.
Continue reading ‘Common sea star (Asterias rubens) coelomic fluid changes in response to short-term exposure to environmental stressors’The effect of pH on the larvae of two sea urchin species using different pH manipulation methods
Published 27 February 2023 Science ClosedTags: biological response, echinoderms, laboratory, methods, morphology, mortality, reproduction
Climate change alters ocean pH, temperature, and salinity, which presents challenges for oceanic organisms, especially those with calcium carbonate skeletons. Our research examines how decreasing pH impacts larval survivorship and calcium carbonate skeletal development of two sea urchin species, Lytechinus variegatus and Arbacia punctulata. Based on previous work in various sea urchin species, it is expected that as pH decreases, survivorship decreases and skeletal malformations increase. Both L. variegatus and A. punctulata have been used in prior studies to explore pH change on survivorship and development, but these studies incorporated various outcomes and pH manipulation methods, limiting how comparable they are. Therefore, we wanted to measure the same outcomes between species and compare the effect of different pH manipulation within species. We altered pH by either HCL addition or CO2 bubbling through seawater. Larvae, at a concentration of 3 larvae/ml, were exposed to seawater of pH 8.4, 8.0, or 7.6. For each treatment, survivorship of 30-40 larvae was measured daily for 10-14 days depending on the trial. Larval malformations were quantified for about 10 larvae from daily fixed samples. Larval arm length, body length, and body width were measured using Image J. For both methods of pH manipulation and both species, there was a statistically significant (p<0.001) decrease in survivorship as pH decreases consistent with the prediction. Preliminary analysis of skeletal deformities suggests malformations increase as pH decreases, but data are still being collected. Similar abnormalities observed between species regardless of pH manipulations include uneven or missing arms and misshapen aboral sides. The effect of pH on larval survivorship and development in L. variegatus and A. punctulata are comparable to observations in other species suggesting effects are consistent across manipulation methods and species. With this research, we can continue to fine-tune methodology and build on our understanding of how climate change-driven ocean acidification can impact species.
Continue reading ‘The effect of pH on the larvae of two sea urchin species using different pH manipulation methods’Contrasting behavioural responses to ocean acidification and warming have the potential to disrupt herbivory
Published 24 February 2023 Science ClosedTags: biological response, crustaceans, echinoderms, mollusks, multiple factors, review, temperature
Highlights
- Global climate change has the potential to disrupt herbivore behaviours.
- Current studies emphasise certain locations, life stage, phyla, and behaviours.
- Behavioural experiments on invertebrate herbivores focus on grazing and movement.
- Where there were effects, typically grazing increased while movement decreased.
- Isolated effects of warming and acidification were often restricted when combined.
Abstract
Global change has the potential to affect organisms and re-structure ecosystems where key species interactions, such as herbivory, are disrupted. The fastest ways individual herbivores – and therefore ecosystems – can respond to climate change is through shifts in behaviour. In marine habitats, environmental changes of particular concern in the future are ocean acidification and warming. Consequently, we reviewed the existing literature in this area of research, to identify if there were any over-arching trends or emerging patterns in behavioural responses of marine herbivores to ocean acidification and warming. We identified that while the body of research is growing, focus remains primarily on few locations (temperate areas), phyla (Mollusca, especially gastropods; Crustacea; Echinodermata), and behaviours (grazing rate, movement). Although representing a relatively narrow view of future herbivory, this review indicates that in many cases, the key behaviours of feeding and movement could be maintained under ocean acidification and warming. However, where change is observed, it is more likely grazing will be enhanced and movement impaired. If such patterns were to manifest under future climates, it would mean that the herbivores present would consume more yet there may be less of them as impaired movement and escape behaviours would have made them more vulnerable to predation. The exact responses will, however, likely be context-dependant. Therefore, we recommend future studies address the research gaps our review identified (i.e., a lack of understanding in tropical and polar regions, economically and ecologically important Crustacean and Echinoderm species, early life history stages, and more behavioural responses in addition to feeding and movement). Understanding the diversity of responses expected under varied contexts will be important to uncover trends in how marine invertebrates will behave under global change.
Continue reading ‘Contrasting behavioural responses to ocean acidification and warming have the potential to disrupt herbivory’Common sea star (Asterias rubens) coelomic fluid changes in response to short-term exposure to environmental stressors
Published 8 February 2023 Science ClosedTags: biological response, echinoderms, laboratory, multiple factors, oxygen, physiology, temperature
Common sea stars (Asterias rubens) are at risk of physiological stress and decline with projected shifts in oceanic conditions. This study assessed changes in coelomic fluid (CF) blood gases, electrolytes, osmolality, and coelomocyte counts in adult common sea stars after exposure to stressors mimicking effects from climate change for 14 days, including decreased pH (−0.4 units, mean: 7.37), hypoxia (target dissolved oxygen ~1.75 mg O2/L, mean: 1.80 mg O2/L), or increased temperature (+10 °C, mean: 17.2 °C) and compared sea star CF electrolytes and osmolality to tank water. Changes in CF blood gases, electrolytes, and/or coelomocyte counts occurred in all treatment groups after stressor exposures, indicating adverse systemic effects with evidence of increased energy expenditure, respiratory or metabolic derangements, and immunosuppression or inflammation. At baseline, CF potassium and osmolality of all groups combined were significantly higher than tank water, and, after exposures, CF potassium was significantly higher in the hypoxia group as compared to tank water. These findings indicate physiological challenges for A. rubens after stressor exposures and, given increased observations of sea star wasting events globally, this provides evidence that sea stars as a broad group are particularly vulnerable to changing oceans.
Continue reading ‘Common sea star (Asterias rubens) coelomic fluid changes in response to short-term exposure to environmental stressors’Combined effects of climate change stressors and predators with contrasting feeding-digestion strategies on a mussel species
Published 1 February 2023 Science ClosedTags: biological response, echinoderms, laboratory, mollusks, morphology, multiple factors, physiology, predation, temperature
Highlights
- Combined effects of climate change stressors and Predator Cues (PC) were evaluated.
- Ocean Acidification (OA), Warming (OW) and PC affected mussel traits.
- At the control temperature (15 °C), mussel byssal biogenesis increased with PC.
- PC affected mussel size, wet mass and calcification rate.
- The effects of starfish PC on some mussel traits were larger than those of snail PC.
Abstract
We investigated the combined effects of Ocean Warming (OW), Acidification (OA) and predator cues (Non-Consumptive Effects; NCEs) of two predators with contrasting feeding-digestion strategies on the mussel Perumytilus purpuratus. We considered starfish-NCEs (partially external digestion) and snail-NCEs (internal digestion). Mussels were exposed for 13 weeks to cross-factored OA (~500 and ~1400 μatm, pCO2) and OW (~15 and ~20 °C) conditions, in the presence/absence of NCEs from one or both predators. Mussels exposed to both NCEs exhibited smaller length and buoyant weight growth than those under control or snail-NCEs conditions. Mussels exposed to starfish-NCEs exhibited smaller wet mass than control mussels. OW and starfish-NCEs in isolation or combined with snail-NCEs increased mussel oxygen consumption. Byssal biogenesis was affected by the three-factors interaction. Clearance rates were affected by the OW × OA interaction. We suggest that mainly starfish-NCEs, in isolation or interacting with OA or/and OW, can threat mussel traits and the associated community.
Continue reading ‘Combined effects of climate change stressors and predators with contrasting feeding-digestion strategies on a mussel species’Population-specific vulnerability to ocean change in a multistressor environment
Published 26 January 2023 Science ClosedTags: biological response, calcification, chemistry, echinoderms, field, laboratory, mesocosms, morphology, mortality, multiple factors, North Pacific, oxygen, physiology, respiration, temperature
Variation in environmental conditions across a species’ range can alter their responses to environmental change through local adaptation and acclimation. Evolutionary responses, however, may be challenged in ecosystems with tightly coupled environmental conditions, where changes in the covariance of environmental factors may make it more difficult for species to adapt to global change. Here, we conduct a 3-month-long mesocosm experiment and find evidence for local adaptation/acclimation in populations of red sea urchins, Mesocentrotus franciscanus, to multiple environmental drivers. Moreover, populations differ in their response to projected concurrent changes in pH, temperature, and dissolved oxygen. Our results highlight the potential for local adaptation/acclimation to multivariate environmental regimes but suggest that thresholds in responses to a single environmental variable, such as temperature, may be more important than changes to environmental covariance. Therefore, identifying physiological thresholds in key environmental drivers may be particularly useful for preserving biodiversity and ecosystem functioning.
Continue reading ‘Population-specific vulnerability to ocean change in a multistressor environment’
