Posts Tagged 'echinoderms'

Adaptive potential of coastal invertebrates to environmental stressors and climate change

Climate change presents multiple stressors that are impacting marine life. As carbon dioxide emissions continue to increase in the atmosphere, atmospheric and sea water temperatures increase. In addition, more carbon dioxide is absorbed into the oceans, reducing pH and aragonite saturation state, resulting in ocean acidification (OA). Tightly coupled with OA is hypoxia due to deep stratified sea water becoming increasingly acidified and deoxygenated. The effects of these climate stressors have been studied in detail for only a few marine animal models. However, there are still many taxa and developmental stages in which we know very little about the impacts. Using genomic techniques, we examine the adaptive potential of three local marine invertebrates under three different climate stressors: marine disease exacerbated by thermal stress, OA, and combined stressors OA with hypoxia (OAH). As sea water temperatures rise, the prevalence of marine diseases increases, as seen in the sea star wasting syndrome (SSWS). The causation of SSWS is still widely debated; however reduced susceptibility to SSWS could aid in understanding disease progression. By examining genetic variation in Pisaster ochraceous collected during the SSWS outbreak, we observed weak separation between symptomatic and asymptomatic individuals. OA has been widely studied in many marine organisms, including Crassostrea gigas. However, limited studies have parsed the effects of OA during settlement, with no studies assessing the functionality of settlement and how it is impacted by OA. We investigated the effects of OA on settlement and gene expression during the transition from larval to juvenile stages in Pacific oysters. While OA and hypoxia are common climate stressors examined, the combined effects have scarcely examined. Further, the impacts of OAH have been narrowly focused on a select few species, with many economically important organisms having no baseline information on how they will persist as OAH severity increases. To address these gaps in our knowledge, we measured genetic variation in metabolic rates during OA for the species Haliotis rufescens to assess their adaptive potential through heritability measurements. We discuss caveats and considerations when utilizing similar heritability estimate methods for other understudied organisms. Together, these studies will provide novel information on the biological responses and susceptibility of difference coastal species to stressors associated with global climate change. These experiments provide information on both the vulnerability of current populations and their genetic potential for adaptation to changing ocean conditions.

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Impact of microplastics and ocean acidification on critical stages of sea urchin (Paracentrotus lividus) early development

Highlights

  • Ocean acidification and microplastics altered the morphology of P. lividus larvae.
  • Ocean acidification and microplastics reduce growth of P. lividus larvae.
  • Alterations occurred before and after larvae start to feed exogenously.
  • The combined effect of both stressors on P. lividus morphology is non additive.
  • SET is an ideal method to study the impact of ocean acidification at a lab scale.

Abstract

One of the major consequences of increasing atmospheric CO2 is a phenomenon known as ocean acidification. This alteration of water chemistry can modulate the impact on marine organisms of other stressors also present in the environment, such as microplastics (MP). The objective of this work was to determine the combined impact of microplastic pollution and ocean acidification on the early development of Paracentrotus lividus. To study these multi-stressor impacts on development P. lividus the sea urchin embryo test (SET) was used. Newly fertilised embryos of P. lividus were exposed to a control treatment (filtered natural seawater), MP (3000 particles/mL), acidified sea water (pH = 7.6), and a combination of MP and acidification (3000 particles/mL + pH = 7.6). After 48, 72, and 96 h measurements of growth and morphometric parameters were taken. Results showed that ocean acidification and MP cause alterations in growth and larval morphology both before and after the larvae start to feed exogenously. The exposure to MP under conditions of ocean acidification did not produce any additional effect on growth, but differences were observed at the morphological level related to a decrease in the width of larvae at 24 h. Overall, changes in larvae shape observed at three key points of their development could modify their buoyancy affecting their ability to obtain and ingest food. Therefore, ocean acidification and MP pollution might compromise the chances of P. lividus to survive in the environment under future scenarios of global climate change.

Continue reading ‘Impact of microplastics and ocean acidification on critical stages of sea urchin (Paracentrotus lividus) early development’

Characterization factors for ocean acidification impacts on marine biodiversity

Rising greenhouse gas emissions do not only accelerate climate change but also make the ocean more acidic. This applies above all to carbon dioxide (CO2). Lower ocean pH levels threaten marine ecosystems and especially strongly calcifying species. Impacts on marine ecosystem quality are currently underrepresented in life cycle assessments (LCAs). Here, we developed characterization factors for the life cycle impact assessment of ocean acidification. Our main contribution was developing new species sensitivity distributions (SSDs), from which we derived effect factors for different impact perspectives: Marginal, linear, and average changes for both the past and four future emission scenarios (RCP2.6, RCP4.5, RCP6.0, and RCP8.5). Based on a dataset that covered five taxa (corals, crustaceans, echinoderms, fishes, molluscs) and three climate zones, we showed significantly higher sensitivities for strongly calcifying than slightly calcifying taxa and in polar regions compared to tropical and temperate regions. Experimental duration, leading to acute, subchronic, or chronic toxicological endpoints, did not significantly affect the species sensitivities. With ocean acidification impacts still accelerating, the future-oriented average effects are higher than the marginal or past-oriented average effects. While our characterization factors are ready for use in LCA, we also point to opportunities for improvement in future developments.

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Responses of sea urchins (Strongylocentrotus intermedius) with different sexes to CO2-induced seawater acidification: histology, physiology, and metabolomics

Highlights

  • Impacts of seawater acidification on different sexes of Strongylocentrotus intermedius were investigated.
  • Specific growth rate and the numbers of mature gametes were measured.
  • A comparative metabolomics analysis was performed.
  • Sex-specific significantly differentially expressed metabolites were identified and annotated.
  • Male S. intermedius may be more sensitive than females in coping with seawater acidification.

Abstract

Responses of different sexes of farmed Strongylocentrotus intermedius to chronic CO2-induced seawater acidification were investigated in 120-day lab-based experiments. Four experimental groups were set up as one control group and three seawater acidification groups. The results showed that 1) Specific growth rate and the numbers of mature gamete cells declined in a pH-dependent way in both sexes of adult S. intermedius. 2) There were differences in SDMs identified in females and males reared in acidified seawater reflecting sex-specific response variation in adult S. intermedius. 3) The number of altered metabolic pathways exhibited a linear increasing trend as seawater pH declined in both sexes of adult S. intermedius. Meanwhile seawater acidification might affect metabolic processes via changing the relative expression and activity of key enzymes controlling the corresponding metabolic pathways of adult S. intermedius.

Continue reading ‘Responses of sea urchins (Strongylocentrotus intermedius) with different sexes to CO2-induced seawater acidification: histology, physiology, and metabolomics’

Effects of seawater acidification on echinoid adult stage: a review

The continuous release of CO2 in the atmosphere is increasing the acidity of seawater worldwide, and the pH is predicted to be reduced by ~0.4 units by 2100. Ocean acidification (OA) is changing the carbonate chemistry, jeopardizing the life of marine organisms, and in particular calcifying organisms. Because of their calcareous skeleton and limited ability to regulate the acid–base balance, echinoids are among the organisms most threatened by OA. In this review, 50 articles assessing the effects of seawater acidification on the echinoid adult stage have been collected and summarized, in order to identify the most important aspects to consider for future experiments. Most of the endpoints considered (i.e., related to calcification, physiology, behaviour and reproduction) were altered, highlighting how various and subtle the effects of pH reduction can be. In general terms, more than 43% of the endpoints were modified by low pH compared with the control condition. However, animals exposed in long-term experiments or resident in CO2-vent systems showed acclimation capability. Moreover, the latitudinal range of animals’ distribution might explain some of the differences found among species. Therefore, future experiments should consider local variability, long-term exposure and multigenerational approaches to better assess OA effects on echinoids.

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Different ecological histories of sea urchins acclimated to reduced pH influence offspring response to multiple stressors

End-of-the-century predictions on carbon dioxide (CO2) driven ocean acidification and the continuous leakage of pesticides from inland to coastal areas are of concern for potential negative effects on marine species’ early life stages which are the most vulnerable to environmental changes. Variations in seawater chemistry related to human activities may interfere with the normal development from embryo to juvenile/adult stage. However, transgenerational studies suggest that the parental generation can influence the offspring phenotype, and thus their performances, based on the environment experienced. Here we compared the transgenerational responses to a multiple stressor scenario in sea urchins (Paracentrotus lividus) that experienced different environments since their settlement: i.e., animals from a highly variable environment, such as the Venice lagoon, versus animals from a coastal area with prevailing oligotrophic conditions in the Northern Adriatic Sea. After long-term maintenance (2 and 6 months) of adult sea urchins at natural and −0.4 units reduced pH, the F1 generations were obtained. Embryos were reared under four experimental conditions: natural and −0.4 pH both in the absence and in the presence of an emerging contaminants’ mixture (glyphosate and aminomethylphosphonic acid at environmentally relevant concentrations, 100 μg/L). A significant detrimental effect of both the parental and the filial pH was highlighted, affecting embryo development and growth. Nonetheless, sea urchins from both sites were able to cope with ocean acidification. The 6-months F1 response was better than that of the 2-months F1. Conversely, the F1 response of the sea urchins maintained at natural conditions did not change sensibly after more prolonged parental exposure. An additive but mild negative effect of the mixture was observed, mostly in lagoon offspring. Results suggest that long-term exposure to reduced pH leads to transgenerational acclimation but does not affect susceptibility to the tested pollutants.

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Low-pH seawater alters indirect interactions in rocky-shore tidepools

Ocean acidification is expected to degrade marine ecosystems, yet most studies focus on organismal-level impacts rather than ecological perturbations. Field studies are especially sparse, particularly ones examining shifts in direct and indirect consumer interactions. Here we address such connections within tidepool communities of rocky shores, focusing on a three-level food web involving the keystone sea star predator, Pisaster ochraceus, a common herbivorous snail, Tegula funebralis, and a macroalgal basal resource, Macrocystis pyrifera. We demonstrate that during nighttime low tides, experimentally manipulated declines in seawater pH suppress the anti-predator behavior of snails, bolstering their grazing, and diminishing the top-down influence of predators on basal resources. This attenuation of top-down control is absent in pools maintained experimentally at higher pH. These findings suggest that as ocean acidification proceeds, shifts of behaviorally mediated links in food webs could change how cascading effects of predators manifest within marine communities.

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Response of Cymodocea nodosa to ocean acidification and warming in the Canary Islands: direct and indirect effects

Hightlights

  • Ocean acidification increase growth and gross primary production of Cymodocea nodosa.
  • The rise of temperature limited the net and gross primary production of Cymodocea nodosa.
  • A positive effect of decrased pH on greater vulnerability to consumption by Paracentrotus lividus.
  • A future scenario of climate change will affect metabolic rates of C.nodosa.
  • Different responses to climate change have been observed by C. nodosa from Canary Islands.

Abstract

As detected in warming and ocean acidification, global change can have profound impact on marine life. Its effects on seagrasses are becoming increasingly well-known, since several studies have focused on the responses of these species to global change conditions. However a few studies have assessed the combined effect of temperature and acidification on seagrasses. Overall in this study, the combined effects of increased ocean temperature and pH levels expected at the end of this century (+5 °C and pH 7.5) on Cymodocea nodosa from Canary Islands, were evaluated for one month through manipulative laboratory experiments. Growth, net production, respiration, gross primary production, chlorophyll-a concentration and its vulnerability to herbivory were quantified. Results showed a positive effect of decreased pH on growth and gross primary production, as well as greater vulnerability to consumption by the sea urchin Paracentrotus lividus. In contrast, increased temperature limited net and gross primary production. This study shows than in future scenarios, C. nodosa from the Canary Islands may be a losing species in the global change stakes.

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Biomineralization: integrating mechanism and evolutionary history

Calcium carbonate (CaCO3) biomineralizing organisms have played major roles in the history of life and the global carbon cycle during the past 541 Ma. Both marine diversification and mass extinctions reflect physiological responses to environmental changes through time. An integrated understanding of carbonate biomineralization is necessary to illuminate this evolutionary record and to understand how modern organisms will respond to 21st century global change. Biomineralization evolved independently but convergently across phyla, suggesting a unity of mechanism that transcends biological differences. In this review, we combine CaCO3 skeleton formation mechanisms with constraints from evolutionary history, omics, and a meta-analysis of isotopic data to develop a plausible model for CaCO3 biomineralization applicable to all phyla. The model provides a framework for understanding the environmental sensitivity of marine calcifiers, past mass extinctions, and resilience in 21st century acidifying oceans. Thus, it frames questions about the past, present, and future of CaCO3 biomineralizing organisms.

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Interactive effects of ocean acidification, ocean warming, and diurnal temperature cycling on antioxidant responses and energy budgets in two sea urchins Strongylocentrotus intermedius and Tripneustes gratilla from different latitudes

Highlights

  • Interactive effects of OA, OW, and DTC on sea urchins are significant.
  • Co-exposure of OA, OW, and DTC induced negative energy budgets in both species.
  • Tropic sea urchins have a better acclimation capacity to climate change.

Abstract

To accurately predict the fitness of marine ectotherms under the climate change scenarios, interactive effects from multiple environmental stressors should be considered, such as ocean acidification (OA), ocean warming (OW) and diurnal temperature cycling (DTC). In this work, we evaluated and compared the antioxidant capacity and metabolism homeostasis of two sea urchins, viz. the temperate species Strongylocentrotus intermedius and the tropical species Tripneustes gratilla, in response to oceanic conditions under a climate change scenario. The two species were treated separately/jointly by acidic (pH 7.6), thermal (ambient temperature + 3 °C), and temperature fluctuating (5 °C fluctuations daily) seawater for 28 days. The activities of antioxidant enzymes (catalase and superoxide dismutase) and the cellular energy allocation in the urchins’ gonads were assessed subsequently. Results showed that exposure to OA, OW, and DTC all induced antioxidant responses associated with metabolism imbalance in both S. intermedius and T. gratilla. The physiological adjustments and energy strategies towards exposure of OA, OW, and DTC are species specific, perhaps owing to the different thermal acclimation of species from two latitudes. Moreover, decrease of cellular energy allocation were detected in both species under combined OA, OW, and DTC conditions, indicating unsustainable bioenergetic states. The decrease of cellular energy allocation is weaker in T. gratilla than in S. intermedius, implying higher acclimation capacity to maintain the energy homeostasis in tropical urchins. These results suggest that climate change might affect the population replenishment of the two sea urchins species, especially for the temperate species.

Continue reading ‘Interactive effects of ocean acidification, ocean warming, and diurnal temperature cycling on antioxidant responses and energy budgets in two sea urchins Strongylocentrotus intermedius and Tripneustes gratilla from different latitudes’

Coupled changes in pH, temperature and dissolved oxygen impact the physiology and ecology of herbivorous kelp forest grazers

Understanding species’ responses to upwelling may be especially important in light of ongoing environmental change. Upwelling frequency and intensity are expected to increase in the future, while ocean acidification and deoxygenation are expected to decrease the pH and dissolved oxygen of upwelled waters. However, the acute effects of a single upwelling event and the integrated effects of multiple upwelling events on marine organisms are poorly understood. Here, we use in situ measurements of pH, temperature, and dissolved oxygen to characterize the covariance of environmental conditions within upwelling-dominated kelp forest ecosystems. We then test the effects of acute (0-3 days) and chronic (1-3 month) upwelling on the performance of two species of kelp forest grazers, the echinoderm, Mesocentrotus franciscanus, and the gastropod, Promartynia pulligo. We exposed organisms to static conditions in a regression design to determine the shape of the relationship between upwelling and performance and provide insights into the potential effects in a variable environment. We found that respiration, grazing, growth, and net calcification decline linearly with increasing upwelling intensity for M. francicanus over both acute and chronic timescales. Promartynia pulligo exhibited decreased respiration, grazing, and net calcification with increased upwelling intensity after chronic exposure, but we did not detect an effect over acute timescales or on growth after chronic exposure. Given the highly correlated nature of pH, temperature, and dissolved oxygen in the California Current, our results suggest the relationship between upwelling intensity and growth in the 3-month trial could potentially be used to estimate growth integrated over long-term dynamic oceanographic conditions for M. franciscanus. Together, these results indicate current exposure to upwelling may reduce species performance and predicted future increases in upwelling frequency and intensity could affect ecosystem function by modifying the ecological roles of key species.

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Ocean acidification, but not environmental contaminants, affects fertilization success and sperm motility in the sea urchin Paracentrotus lividus

Ocean acidification poses an increasing concern for broadcast spawning species that release gametes in the water column where fertilization occurs. Indeed, the functionality of gametes and their interactions may be negatively affected by reduced pH. Susceptibility to other environmental stressors, such as pollutants, may be also altered under acidified conditions, resulting in more detrimental effects. To verify this hypothesis, combined exposures to CO2-driven acidification and environmentally relevant concentrations (0.5 µg/L) of three contaminants (caffeine, diclofenac, and PFOS, all singularly or in mixture) were carried out to highlight potential negative effects on fertilization success and motility of sperm in the sea urchin Paracentrotus lividus. Our results showed a significant reduction in the percentage of fertilized eggs when sperm were pre-exposed to reduced pH (ambient pH minus 0.4 units) compared to that of controls (ambient, pH = 8.1). Sperm speed and motility also decreased when sperm were activated and then exposed at reduced pH. Conversely, at both pH values tested, no significant effect due to the contaminants, nor of their interaction with pH, was found on any of the biological endpoints considered.

Continue reading ‘Ocean acidification, but not environmental contaminants, affects fertilization success and sperm motility in the sea urchin Paracentrotus lividus’

Upper environmental pCO2 drives sensitivity to ocean acidification in marine invertebrates

Minimizing the impact of ocean acidification requires an understanding of species responses and environmental variability of population habitats. Whereas the literature is growing rapidly, emerging results suggest unresolved species- or population-specific responses. Here we present a meta-analysis synthesizing experimental studies examining the effects of pCO2 on biological traits in marine invertebrates. At the sampling locations of experimental animals, we determined environmental pCO2 conditions by integrating data from global databases and pCO2 measurements from buoys. Experimental pCO2 scenarios were compared with upper pCO2 using an index considering the upper environmental pCO2. For most taxa, a statistically significant negative linear relationship was observed between this index and mean biological responses, indicating that the impact of a given experimental pCO2 scenario depends on the deviation from the upper pCO2 level experienced by local populations. Our results highlight the importance of local biological adaptation and the need to consider present pCO2 natural variability while interpreting experimental results.

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On the effects of temperature and pH on tropical and temperate holothurians

Ocean acidification and increased ocean heat content has direct and indirect effects on marine organisms such as holothurians (sea cucumbers) that are vulnerable to changes in pH and temperature. These environmental factors have the potential to influence organismal performance and fitness at different life stages. Tropical and temperate holothurians are more vulnerable to temperature and pH than those from colder water environments. The high level of environmental variation observed in the oceans could influence organismal responses and even produce a wide spectrum of compensatory physiological mechanisms. It is possible that in these areas, larval survival will decline by up to 50% in response to a reduction of 0.5 pH units. Such reduction in pH may trigger low intrinsic growth rates and affect the sustainability of the resource. Here we describe the individual and combined effects that temperature and pH could produce in these organisms. We also describe how these effects can scale from individuals to the population level by using age-structured spatial models in which depensation can be integrated. The approach shows how physiology can improve the conservation of the resource based on the restriction of growth model parameters and by including a density threshold, below which the fitness of the population, specifically intrinsic growth rate, decreases.

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Lead in the marine environment: concentrations and effects on invertebrates

Lead (Pb) is a non-essential metal naturally present in the environment and often complexed with other elements (e.g., copper, selenium, zinc). This metal has been used since ancient Egypt and its extraction has grown in the last centuries. It has been used until recently as a fuel additive and is currently used in the production of vehicle batteries, paint, and plumbing. Marine ecosystems are sinks of terrestrial contaminations; consequently, lead is detected in oceans and seas. Furthermore, lead is not biodegradable. It remains in soil, atmosphere, and water inducing multiple negative impacts on marine invertebrates (key species in trophic chain) disturbing ecological ecosystems. This review established our knowledge on lead accumulation and its effects on marine invertebrates (Annelida, Cnidaria, Crustacea, Echinodermata, and Mollusca). Lead may affect different stages of development from fertilization to larval development and can also lead to disturbance in reproduction and mortality. Furthermore, we discussed changes in the seawater chemistry due to Ocean Acidification, which can affect the solubility, speciation, and distribution of the lead, increasing potentially its toxicity to marine invertebrates.

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Direct and latent effects of ocean acidification on the transition of a sea urchin from planktonic larva to benthic juvenile

Ongoing ocean acidification (OA) is expected to affect marine organisms and ecosystems. While sea urchins can survive a wide range of pH, this comes at a high energetic cost, and early life stages are particularly vulnerable. Information on how OA affects transitions between life-history stages is scarce. We evaluated the direct and indirect effects of pH (pHT 8.0, 7.6 and 7.2) on the development and transition between life-history stages of the sea urchin Strongylocentrotus droebachiensis, from fertilization to early juvenile. Continuous exposure to low pH negatively affected larval mortality and growth. At pH 7.2, formation of the rudiment (the primordial juvenile) was delayed by two days. Larvae raised at pH 8.0 and transferred to 7.2 after competency had mortality rates five to six times lower than those kept at 8.0, indicating that pH also has a direct effect on older, competent larvae. Latent effects were visible on the larvae raised at pH 7.6: they were more successful in settling (45%) and metamorphosing (30%) than larvae raised at 8.0 (17 and 1% respectively). These direct and indirect effects of OA on settlement and metamorphosis have important implications for population survival.

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Integrative assessment of sediments affected by CO2 enrichment: a case study in the Bay of Santos—SP, Brazil

CO2 enrichment in the marine environment caused by leakages from carbon capture and storage technologies may occur over operational procedures. An integrated approach using weight-of-evidence was applied to assess the environmental risk associated with the acidification caused by CO2 enrichment in coastal sediments from Santos (Brazil). Chemical analyses (metal(loid)s and organic contaminant (e.g., hydrocarbons), toxicity tests (amphipods mortality, sea-urchin embryo-larval development) and macro-benthic community structure alteration assessment were performed with different acidified scenarios (pH 8.0–6.0) for two stations with different contamination degrees. These lines of evidence were statistically analyzed and integrated (multivariate analysis and ANOVA). Results of toxicity showed significant chronic effects starting at pH 7.0 while acute effects were observed starting at pH 6.5. The macro-benthic community integrity showed significant differences for all treatments at the Piaçaguera channel station, considered to be moderately contaminated. Results from the multivariate analysis correlated toxic effects and increase in the mobility of some elements with acidification. Also, the biological indexes were correlated with concentrations of dissolved Zn in seawater. The pH of 6.0 was extremely toxic for marine life due to its high acidification and metal bioavailability. The approach herein identified and discriminated the origin of the degradation caused by the acidification related to the enrichment of CO2.

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Response of microbial communities on culturing plates of post-settlement sea cucumbers to seawater acidification and warming

Seawater acidification and warming have been found to affect the early life of many marine organisms, but their effects on the microbial community in the environment related to the early development stage of aquaculture species have been rarely investigated. To understand how seawater acidification and warming impact the microbial community in aquaculture systems, we designed four microcosms to monitor and characterize the microbial composition on the corrugated plates in the Apostichopus japonicus culture tanks during its post-settlement stage. High-throughput 16S rRNA sequencing revealed that the bacterial community composition varied significantly in different periods of incubation. The bacterial diversity and community composition were obviously changed by seawater acidification and warming in the early period and then tended to revert to the level of the control group. Acidification significantly increased the relative abundance of dominant families Rhodobacteraceae and Flavobacteriaceae in the early period, suggesting that microbiota could increase the abundance of predominant taxa to adapt to increased CO2 concentration and reconstruct a stable community structure. No interaction effect of both factors was observed in the combined group. Results reveal that the microbial communities on the corrugated plates in A. japonicus culture tank were affected in the early period of incubation, and could then acclimatize to the increased CO2 and temperature. This study provides new insights into the variation and adaptation responses of the microbiota in aquaculture systems to seawater acidification and warming.

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Effects of ocean acidification on the performance and interaction of fleshy macroalgae and a grazing sea urchin

Highlights

  • We investigated the direct and indirect effects of CO2 on an urchin and macroalgae.
  • Elevated CO2 increased production of fleshy macroalgae biomass but not photosynthesis.
  • Urchin respiration, biomass, righting time, and consumption rate were unaffected.
  • Reduced algal nutrition interacted with impaired chemosensing to preserve foraging.
  • Foraging and consumption suggest sustained trophic interactions under acidification.

Abstract

When predicting the response of marine ecosystems to climate change, it is increasingly recognized that understanding the indirect effects of ocean acidification on trophic interactions is as important as studying direct effects on organism physiology. Furthermore, comprehensive studies that examine these effects simultaneously are needed to identify and link the underlying mechanisms driving changes in species interactions. Using an onshore ocean acidification simulator system, we investigated the direct and indirect effects of elevated seawater pCO2 on the physiology and trophic interaction of fleshy macroalgae and the grazing sea urchin Lytechinus variegatus. Macroalgal (Dictyota spp.) biomass increased despite decreased photosynthetic rates after two-week exposure to elevated pCO2. Algal tissue carbon content remained constant, suggesting the use of alternative carbon acquisition pathways beneficial to growth under acidification. Higher C:N ratios driven by a slight reduction in N content in algae exposed to elevated pCO2 suggest a decrease in nutritional content under acidification. Urchin (L. variegatus) respiration, biomass, and righting time did not change significantly after six-week exposure to elevated pCO2, indicating that physiological stress and changes in metabolism are not mechanisms through which the trophic interaction was impacted. Correspondingly, urchin consumption rates of untreated macroalgae (Caulerpa racemosa) were not significantly affected by pCO2. In contrast, exposure of urchins to elevated pCO2 significantly reduced the number of correct foraging choices for ambient macroalgae (Dictyota spp.), indicating impairment of urchin chemical sensing under acidification. However, exposure of algae to elevated pCO2 returned the number of correct foraging choices in similarly exposed urchins to ambient levels, suggesting alongside higher C:N ratios that algal nutritional content was altered in a way detectable by the urchins under acidification. These results highlight the importance of studying the indirect effects of acidification on trophic interactions simultaneously with direct effects on physiology. Together, these results suggest that changes to urchin chemical sensing and algal nutritional quality are the driving mechanisms behind surprisingly unaltered urchin foraging behavior for fleshy macroalgae under joint exposure to ocean acidification. Consistent foraging behavior and consumption rates suggest that the trophic interaction between L. variegatus and fleshy macroalgae may be sustained under future acidification. However, increases in fleshy macroalgal biomass driven by opportunistic carbon acquisition strategies have the potential to cause ecological change, depending on how grazer populations respond. Additional field research is needed to determine the outcome of these results over time and under a wider range of environmental conditions.

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Biological effects of the antihypertensive losartan under different ocean acidification scenarios

Highlights

  • Losartan was quantified in samples of marine water (up to 7.63 ng/L) and sediment (up to 3.10 ng/g).
  • Sediment spiked with an environmental concentration of losartan affected lysosomal stability.
  • Losartan effects were pH dependent and pH effects were dependent on the concentration of losartan.
  • Ocean acidification exacerbates the negative effects of losartan in waterborne exposure.

Abstract

Since the last decade, several studies have reported the presence and effects of pharmaceutical residues in the marine environment, especially those of the antihypertensive class, such as losartan. However, there is little knowledge about the physiological effects of losartan in marine invertebrates regarding its behavior under possible coastal ocean acidification scenarios. The objective of this study was to evaluate biological effects on marine organisms at different levels of the biological organization caused by the compound losartan in water and sediment under coastal ocean acidification scenarios. Water and sediment samples were collected at five sites around the Santos Submarine Sewage outfall (SSO) and two sites around the Guarujá Submarine Sewage Outfall (GSO). Losartan was found in concentrations ranging from <LOD to 7.63 ng/L in water and from <LOQ to 3.10 ng/g in sediments. Statistical analysis showed interactive effects pH and losartan on the toxicity results. The water toxicity test with Echinometra lucunter embryos/larvae showed LOECs 50–100 mg/L, with values decreasing as the pH decreased. In the sediment assays, LOEC value for sea urchin embryo-larval development was 1.0 μg/g for all tested pHs. Regarding the lysosomal membrane stability assays with adult bivalves, a LOEC of 3000 ng/L was found for Perna perna in water exposure (both at pH 8.0 and 7.6). Effects for Mytella guyanensis were observed at environmentally relevant concentrations in sediment (LOEC = 3 ng/g at pH 8.0 and 7.6). This study demonstrated that coastal ocean acidification by itself causes effects on marine invertebrates, but can also increase the negative effects of losartan in waterborne exposure. There is a need to deepen the studies on the ecotoxicity of pharmaceutical residues and acidification of the marine environment.

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