Posts Tagged 'crustaceans'

Effect of different pCO2 concentrations in seawater on meiofauna: abundance of communities in sediment and survival rate of harpacticoid copepods

The amount of CO2 dissolved in the ocean has been increasing continuously, and the results using climate change models show that the CO2 concentration of the ocean will increase by over 1000 ppm by 2100. Ocean acidification is expected to have a considerable impact on marine ecosystems. To find out about the impacts of ocean acidification on meiofaunal communities and copepod groups, we analyzed the differences in the abundance of meiofauna communities in sediment and the survival rate of harpacticoid copepod assemblages separated from the sediment, between 400 and 1000 ppm pCO2 for a short period of 5 days. In experiments with communities in sediments exposed to different pCO2 concentrations, there was no significant difference in the abundance of total meiofauna and nematodes. However, the abundance of the harpacticoid copepod community was significantly lower at 1000 ppm than that at 400 ppm pCO2. On the other hand, in experiments with assemblages of harpacticoid copepods directly exposed to seawater, there was no significant difference in their survival rates between the two concentrations. Our findings suggest that a CO2 concentration of 1000 ppm in seawater can cause changes in the abundance of specific taxa such as harpacticoid copepods among the meiofauna communities in sediments.

Continue reading ‘Effect of different pCO2 concentrations in seawater on meiofauna: abundance of communities in sediment and survival rate of harpacticoid copepods’

Caribbean king crab larvae and juveniles show tolerance to ocean acidification and ocean warming

Coastal habitats are experiencing decreases in seawater pH and increases in temperature due to anthropogenic climate change. The Caribbean king crab, Maguimithrax spinosissimus, plays a vital role on Western Atlantic reefs by grazing macroalgae that competes for space with coral recruits. Therefore, identifying its tolerance to anthropogenic stressors is critically needed if this species is to be considered as a potential restoration management strategy in coral reef environments. We examined the effects of temperature (control: 28 °C and elevated: 31 °C) and pH (control: 8.0 and reduced pH: 7.7) on the king crab’s larval and early juvenile survival, molt-stage duration, and morphology in a fully crossed laboratory experiment. Survival to the megalopal stage was reduced (13.5% lower) in the combined reduced pH and elevated temperature treatment relative to the control. First-stage (J1) juveniles delayed molting by 1.5 days in the reduced pH treatment, while second-stage (J2) crabs molted 3 days earlier when exposed to elevated temperature. Juvenile morphology did not differ among treatments. These results suggests that juvenile king crabs are tolerant to changes associated with climate change. Given the important role of the king crab as a grazer of macroalgae, its tolerance to climate stressors suggests that it could benefit restoration efforts aimed at making coral reefs more resilient to increasingly warm and acidic oceans into the future.

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Effects of shellfish and macro-algae IMTA in North China on the environment, inorganic carbon system, organic carbon system, and sea–air CO2 fluxes

Shellfish and macro-algae integrated multi-trophic aquaculture (IMTA) contribute greatly to the sustainability of aquaculture. However, the effects of large-scale shellfish and macro-algae aquaculture on the functions of the ocean carbon sink are not clear. To clarify these effects, we studied the spatial and temporal changes of inorganic and organic carbon systems in seawater under different aquaculture modes (monoculture or polyculture of shellfish and macro-algae) in Sanggou Bay, together with the variation of other environmental factors. The results show that the summertime dissolved oxygen (DO) concentration in the shellfish culture zone was significantly lower than other zones (p < 0.05), with a minimum value of 7.07 ± 0.25 mg/L. The variation of pH and total alkalinity (TA) were large across different culture modes, and the seawater in the shellfish culture zone had the lowest pH and TA than the other zones. Seasonal environment and aquaculture modes significantly affected the variation of dissolved inorganic carbon (DIC), CO2 partial pressure (pCO2), dissolved organic carbon (DOC), and particulate organic carbon (POC) concentrations. The highest values of DIC, pCO2, and POC appeared in summer, and the lowest appeared in winter. For DOC concentration, the lowest value appeared in autumn. Spatially, DIC and pCO2 were highest in the shellfish culture zone and lowest in the macro-algae culture zone, DOC was highest in the macro-algae culture zone and lowest in the shellfish culture zone, and POC was lower in the shellfish culture zone and macro-algae culture zone and higher in the remaining zones. The results of sea–air CO2 fluxes showed that except for the shellfish culture zone during summertime, which released CO2 to the atmosphere, all culture zones were the sinks of atmospheric CO2 during the culture period, with the whole bay being a strong CO2 sink during autumn and winter. In summary, large-scale shellfish–macro-algae IMTA plays an important role in the local carbon cycle and contributes to mitigating ocean acidification and hypoxia.

Continue reading ‘Effects of shellfish and macro-algae IMTA in North China on the environment, inorganic carbon system, organic carbon system, and sea–air CO2 fluxes’

Multigenerational life-history responses to pH in distinct populations of the copepod Tigriopus californicus

Intertidal zones are highly dynamic and harsh habitats: organisms that persist there must face many stressors, including drastic changes in seawater pH, which can be strongly influenced by biological processes. Coastal ecosystems are heterogeneous in space and time, and populations can be exposed to distinct selective pressures and evolve different capacities for acclimation to changes in pH. Tigriopus californicus is a harpacticoid copepod found in high-shore rock pools on the west coast of North America. It is a model system for studying population dynamics in diverse environments, but little is known about its responses to changes in seawater pH. I quantified the effects of pH on the survivorship, fecundity, and development of four T. californicus populations from San Juan Island, Washington, across three generations. For all populations and generations, copepod cultures had lower survivorship and delayed development under extended exposure to higher pH treatments (pH 7.5 and pH 8.0), whereas cultures maintained in lower pH (7.0) displayed stable population growth over time. Reciprocal transplants between treatments demonstrated that these pH effects were reversible. Life histories were distinct between populations, and there were differences in the magnitudes of pH effects on development and culture growth that persisted through multiple generations. These results suggest that T. californicus might not have the generalist physiology that might be expected of an intertidal species, and it could be adapted to lower average pH conditions than those that occur in adjacent open waters.

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A framework for assessing harvest strategy choice when considering multiple interacting fisheries and a changing environment: the example of eastern Bering Sea crab stocks

Ecosystem Based Fisheries Management aims to broaden the set of factors included in assessments and management decision making but progress with implementation remains limited. We developed a framework that examines the consequences of temporal changes in temperature and ocean pH on yield and profit of multiple interacting stocks including eastern Bering Sea (EBS) snow, southern Tanner, and red king crab. Our analyses integrate experimental work on the effects of temperature and ocean pH on growth and survival of larval and juvenile crab and monitoring data from surveys, fishery landings, and at-sea observer programs. The impacts of future changes in temperature and ocean pH on early life history have effects that differ markedly among stocks, being most pessimistic for Bristol Bay red king crab and most optimistic for EBS snow crab. Our results highlight that harvest control rules that aim to maximize yield lead to lower profits than those that aim to maximize profit. Similarly, harvest control rules that aim to maximize profit lead to lower yields than those that aim to maximize yield, but differences are less pronounced. Maximizing profits has conservation benefits, especially when the implemented harvest control rule reduces fishing mortality if population biomass is below a threshold level.

Continue reading ‘A framework for assessing harvest strategy choice when considering multiple interacting fisheries and a changing environment: the example of eastern Bering Sea crab stocks’

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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Species specific responses to grazer cues and acidification in phytoplankton- winners and losers in a changing world

Phytoplankton induce defensive traits in response to chemical alarm signals from grazing zooplankton. However, these signals are potentially vulnerable to changes in pH and it is not yet known how predator recognition may be affected by ocean acidification. We exposed four species of diatoms and one toxic dinoflagellate to future pCO2 levels, projected by the turn of the century, in factorial combinations with predatory cues from copepods (copepodamides). We measured the change in growth, chain length, silica content, and toxin content. Effects of increased pCO2 were highly species specific. The induction of defensive traits was accompanied by a significant reduction in growth rate in three out of five species. The reduction averaged 39% and we interpret this as an allocation cost associated with defensive traits. Copepodamides induced significant chain length reduction in three of the four diatom species. Under elevated pCO2 Skeletonema marinoi reduced silica content by 30% and in Alexandrium minutum the toxin content was reduced by 30%. Using copepodamides to induce defensive traits in the absence of direct grazing provides a straightforward methodology to assess costs of defense in microplankton. We conclude that copepodamide signalling system is likely robust to ocean acidification. Moreover, the variable responses of different taxa to ocean acidification suggest that there will be winners and losers in a high pCO2 world, and that ocean acidification may have structuring effects on phytoplankton communities.

Continue reading ‘Species specific responses to grazer cues and acidification in phytoplankton- winners and losers in a changing world’

Elevated temperature and low pH affect the development, reproduction, and feeding preference of the tropical cyclopoid copepod Oithona rigida

The copepod genus Oithona is among the most abundant mesozooplankton in both eutrophic and oligotrophic waters. This paper reports the individual and combined effect of temperature and pH on the development, reproduction success, and feeding preference of the tropical species Oithona rigida. Experiments were conducted at different temperature (28, 30, 31, and 32°C) and pH (7.7, 7.9, and 8.1) conditions. Effects on vital rates were observed for different developmental stages and adult males. Sex ratio varied from near 1:1 at 28°C to almost entirely female at 32°C. Egg production and hatching success were maximum at 30°C and pH at 7.9. O. rigida preferred the motile green alga Dunaliella salina in terms of ingestion rate, feed selectivity, and egg production across all the temperature and pH conditions. Long-term studies are needed to validate the adaptability of this species to a variety of climate impacts.

Continue reading ‘Elevated temperature and low pH affect the development, reproduction, and feeding preference of the tropical cyclopoid copepod Oithona rigida’

Loss of transcriptional plasticity but sustained adaptive capacity after adaptation to global change conditions in a marine copepod

Adaptive evolution and phenotypic plasticity will fuel resilience in the geologically unprecedented warming and acidification of the earth’s oceans, however, we have much to learn about the interactions and costs of these mechanisms of resilience. Here, using 20 generations of experimental evolution followed by three generations of reciprocal transplants, we investigated the relationship between adaptation and plasticity in the marine copepod, Acartia tonsa, in future global change conditions (high temperature and high CO2). We found parallel adaptation to global change conditions in genes related to stress response, gene expression regulation, actin regulation, developmental processes, and energy production. However, reciprocal transplantation showed that adaptation resulted in a loss of transcriptional plasticity, reduced fecundity, and reduced population growth when global change-adapted animals were returned to ambient conditions or reared in low food conditions. However, after three successive transplant generations, global change-adapted animals were able to match the ambient-adaptive transcriptional profile. Concurrent changes in allele frequencies and erosion of nucleotide diversity suggest that this recovery occurred via adaptation back to ancestral conditions. These results demonstrate that while plasticity facilitated initial survival in global change conditions, it eroded after 20 generations as populations adapted, limiting resilience to new stressors and previously benign environments.

Continue reading ‘Loss of transcriptional plasticity but sustained adaptive capacity after adaptation to global change conditions in a marine copepod’

Effects of ocean acidification and warming on the development and biochemical responses of juvenile shrimp Palaemon elegans (Rathke, 1837)

Highlights

  • P. elegans juveniles were exposed to four combinations of pH and temperature.
  • Higher temperatures impacted the condition factor, moulting events, protein content and fatty acid profile.
  • Lower pH levels slightly decreased the lipid content.
  • Combined warming and acidification could exacerbate negative consequences of shrimp’s body size and biochemical profile.

Abstract

Anthropogenic CO2 emissions have led to the warming and acidification of the oceans. Although, there is a growing of evidence showing that simultaneous occurrence of ocean acidification and ocean warming are threats to marine organisms, information on their combined effect on coastal shrimp species remains scarce. The purpose of this study was to estimate the combined effects of seawater acidification and warming on growth-related traits and biochemical responses of P. elegans juveniles. In this work, shrimp were exposed for 65 days at 4 experimental conditions: pH 8.10 * 18 °C, pH 7.80 * 18 °C, pH 8.10 * 22 °C, pH 7.80 * 22 °C. The results showed that low pH decreases the lipid content by ∼13% (p < 0.05). Higher temperature reduced the condition factor by ∼11%, the protein content by ∼20%, the PUFA by ∼8,6% and shortened moulting events by 5 days (p > 0.05) while the SFA increased ∼9.4%. The decrease in condition factor and protein was however more prominent in organisms exposed to the combination of pH and temperature with a decrease of ∼13% and ∼21%, respectively. Furthermore, essential fatty acids as EPA and DHA also decreased by ∼20% and ∼6.6% in low pH and higher temperature condition. Despite this study suggest that warming may have a greater impact than acidification, it has been shown that their combined effect can exacerbate these impacts with consequences for the shrimp’s body size and biochemical profile.

Continue reading ‘Effects of ocean acidification and warming on the development and biochemical responses of juvenile shrimp Palaemon elegans (Rathke, 1837)’

Multiple-stressor effects of ocean acidification, warming and predation risk cues on the early ontogeny of a rocky-shore keystone gastropod

Highlights

  • Snail feeding was reduced by Non-Consumptive Effects (NCEs) of a predatory crab.
  • Snail feeding was not reduced by ocean acidification (OA) and warming (OW).
  • Snail tenacity was reduced by OA but only under predatory crab NCEs.
  • Snail survival and growth were resilient to OA, OW and NCEs.

Abstract

To understand how climate change stressors might affect marine organisms and support adequate projections it is important to know how multiple stressors may be modulated by the presence of other species. We evaluated the direct effects of ocean warming (OW) and ocean acidification (OA) together with non-consumptive effects (NCEs) of the predatory crab Acanthocyclus hassleri on early ontogeny fitness-related traits of the commercially important rocky-shore keystone gastropod Concholepas concholepas. We measured the response of nine traits to these stressors at either the organismal level (survival, growth, feeding rates, tenacity, metabolic rate, calcification rate) or sub-organismal level (nutritional status, ATP-supplying capacity, stress condition). C. concholepas survival was not affected by any of the stressors. Feeding rates were not affected by OW or OA; however, they were reduced in the presence of crab NCEs compared with control conditions. Horizontal tenacity was affected by the OA × NCEs interaction; in the presence of NCEs, OA reduced tenacity. The routine metabolic rate, measured by oxygen consumption, increased significantly with OW. Nutritional status assessment determined that carbohydrate content was not affected by any of the stressors. However, protein content was affected by the OA × NCEs interaction; in the absence of NCEs, OA reduced protein levels. ATP-supplying capacity, measured by citrate synthase (CS) activity, and cellular stress condition (HSP70 expression) were reduced by OA, with reduction in CS activity found particularly at the high temperature. Our results indicate C. concholepas traits are affected by OA and OW and the effects are modulated by predator risk (NCEs). We conclude that some C. concholepas traits are resilient to climate stressors (survival, growth, horizontal tenacity and nutritional status) but others are affected by OW (metabolic rate), OA (ATP-supplying capacity, stress condition), and NCEs (feeding rate). The results suggest that these negative effects can adversely affect the associated community.

Continue reading ‘Multiple-stressor effects of ocean acidification, warming and predation risk cues on the early ontogeny of a rocky-shore keystone gastropod’

Meta-analysis suggests variable, but pCO2-specific, effects of ocean acidification on crustacean biomaterials

Crustaceans comprise an ecologically and morphologically diverse taxonomic group. They are typically considered resilient to many environmental perturbations found in marine and coastal environments, due to effective physiological regulation of ions and hemolymph pH, and a robust exoskeleton. Ocean acidification can affect the ability of marine calcifying organisms to build and maintain mineralized tissue and poses a threat for all marine calcifying taxa. Currently, there is no consensus on how ocean acidification will alter the ecologically-relevant exoskeletal properties of crustaceans. Here, we present a systematic review and meta-analysis on the effects of ocean acidification on the crustacean exoskeleton, assessing both exoskeletal ion content (calcium and magnesium) and functional properties (biomechanical resistance and cuticle thickness). Our results suggest that the effect of ocean acidification on crustacean exoskeletal properties varies based upon seawater pCO2 and species identity, with significant levels of heterogeneity for all analyses. Calcium and magnesium content were significantly lower in animals held at pCO2 levels of 1500-1999 μatm as compared to those under ambient pCO2. At lower pCO2 levels, however, statistically significant relationships between changes in calcium and magnesium content within the same experiment were observed: a negative relationship between calcium and magnesium content at pCO2 of 500-999 μatm and a positive relationship at 1000-1499 μatm. Exoskeleton biomechanics, such as resistance to deformation (microhardness) and shell strength, also significantly decreased under pCO2 regimes of 500-999 μatm and 1500-1999 μatm, indicating functional exoskeletal change coincident with decreases in calcification. Overall, these results suggest that the crustacean exoskeleton can be susceptible to ocean acidification at the biomechanical level, potentially predicated on changes in ion content, when exposed to high influxes of CO2. Future studies will need to accommodate the high variability of crustacean responses to ocean acidification, as well as ecologically-relevant ranges of pCO2 conditions, when designing experiments with conservation-level endpoints.

Continue reading ‘Meta-analysis suggests variable, but pCO2-specific, effects of ocean acidification on crustacean biomaterials’

Physiological responses of the symbiotic shrimp Ancylocaris brevicarpalis and its host sea anemone Stichodactyla haddoni to ocean acidification

Highlights

  • Low pH condition have triggered the lipid peroxidation in anemone and shrimp.
  • AP showed less values in shrimp and anemone could be because of low pH stress.
  • Antioxidant enzymes showed upward tendency as an indicator for oxidative stress.
  • Short term exposure had adversely affected the physiology of anemone and shrimp.

Abstract

In this study, the physiology of symbiotic ‘peacock-tail’ shrimp Ancylocaris brevicarpalis and its host ‘Haddon’s carpet’ sea anemone Stichodactyla haddoni were tested under lowered pH (7.7) and control (8.1) conditions. The biochemical responses such as digestive enzyme (AP), organic acids (lactate and succinate), oxidative damages (MDA), antioxidants metabolites/enzymes (ASC, GSH, SODCATAPXGPX, GR, POX, and PHOX), and detoxification enzyme (GST) were measured. The AP showed insignificantly reduced values in both the organisms in lowered pH conditions compared to control indicating the effect of abiotic stress. The hierarchical clustering analysis indicated low MDA in sea anemone can be explained by higher POX, APX, GR, ASC, and GSH levels compared to shrimps. However, the detoxification enzyme GST showed less activity in sea anemones compared to shrimps. The results suggest that A. brevicarpalis and sea anemone S. haddoni may have deleterious effects when exposed to short-term acidification stress.

Continue reading ‘Physiological responses of the symbiotic shrimp Ancylocaris brevicarpalis and its host sea anemone Stichodactyla haddoni to ocean acidification’

Moderate acidification mitigates the toxic effects of phenanthrene on the mitten crab Eriocheir sinensis

Highlights

  • Phenanthrene at environmentally-relevant concentration caused toxic effects on crabs.
  • Acidification (pH6.5) mitigated the toxic effects of phenanthrene on crabs.
  • Phenanthrene caused enrichment of disease and immune related pathways.
  • The interaction of pH 6.5 and phenanthrene made the metabolic pathway more enriched.

Abstract

Freshwater acidification and phenanthrene may result in complex adverse effects on aquatic animals. Juvenile Chinese mitten crabs (Eriocheir sinensis) were exposed to different pH levels (7.8, 6.5, and 5.5) under phenanthrene (PHE) (0 (control) and 50 μg/L) conditions for 14 days. Antioxidant and transcriptomic responses were determined under stress conditions to evaluate the physiological adaptation of crabs. Under the control pH 7.8, PHE led to significantly reduced activities of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR) and glutathione S-transferase (GST), but increased glutathione peroxidase (GSH-Px), 7-ethoxyresorufin-o-deethylase (EROD) activities, and malondialdehyde (MDA) levels. However, moderate acidification (pH 6.5) changed PHE effects by increasing antioxidant enzymes. Acidification generally reduced SOD, GPx, GST and EROD activities, but increased CAT, GR, MDA. Compared with pH7.8 group, pH7.8 × PHE and pH6.5 × PHE groups had 1148 and 1498 differentially expressed genes, respectively, with “Biological process” being the main category in the two experimental groups. pH7.8 × PHE treatment caused significant enrichment of disease and immune-related pathways, while under pH6.5 × PHE, more pathways related to metabolism, detoxification, environmental information processing, and energy supply were significantly enriched. Thus, PHE had a significant inhibitory effect on antioxidant performance in crabs, while moderate acidification (pH6.5) mitigated the toxic effects of PHE. Overall, moderate acidification has a positive effect on the defense against the negative effects of PHE in Chinese mitten crabs, and this study provides insights into the defense mechanism of crustaceans in response to combined stress of acidification and PHE.

Continue reading ‘Moderate acidification mitigates the toxic effects of phenanthrene on the mitten crab Eriocheir sinensis’

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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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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Effects of ocean acidification on molting, oxidative stress, and gut microbiota in juvenile horseshoe crab Tachypleus tridentatus

Anthropogenic elevation of atmospheric carbon dioxide (CO2) drives global-scale ocean acidification (OA), which has aroused widespread concern for marine ecosystem health. The tri-spine horseshoe crab (HSC) Tachypleus tridentatus has been facing the threat of population depletion for decades, and the effects of OA on the physiology and microbiology of its early life stage are unclear. In this study, the 1st instar HSC larvae were exposed to acidified seawater (pH 7.3, pH 8.1 as control) for 28 days to determine the effects of OA on their growth, molting, oxidative stress, and gut microbiota. Results showed that there were no significant differences in growth index and molting rate between OA group and control group, but the chitinase activity, β-NAGase activity, and ecdysone content in OA group were significantly lower than those of the control group. Compared to the control group, reactive oxygen species (ROS) and malondialdehyde (MDA) contents in OA group were significantly increased at the end of the experiment. Superoxide dismutase (SOD), catalase (CAT), and alkaline phosphatase (AKP) activities increased first and then decreased, glutathione peroxidase (GPX) decreased first and then increased, and GST activity changed little during the experiment. According to the result of 16S rRNA sequencing of gut microbiota, microbial-mediated functions predicted by PICRUSt showed that “Hematopoietic cell lineage,” “Endocytosis,” “Staphylococcus aureus infection,” and “Shigellosis” pathways significantly increased in OA group. The above results indicate that OA had no significant effect on growth index and molting rate but interfered with the activity of chitinolytic enzymes and ecdysone expression of juvenile horseshoe crabs, and caused oxidative stress. In addition, OA had adverse effects on the immune defense function and intestinal health. The present study reveals the potential threat of OA to T. tridentatus population and lays a foundation for the further study of the physiological adaptation mechanism of juvenile horseshoe crabs to environmental change.

Continue reading ‘Effects of ocean acidification on molting, oxidative stress, and gut microbiota in juvenile horseshoe crab Tachypleus tridentatus’

Effects of water acidification on immune responses of the gercacinid,
Cardiosoma armatum (Herklots, 1851)

The biological response to chemical pollutants reflects the acid–base status of an aquatic ecosystem. The gercacinid, Cardiosoma armatum (75±0.1 g) was exposed to acidified waters to evaluate the effects on its immune parameters. The crabs were exposed to pH 4.0, 5.0, 6.0 and 7.8 (control) for 28 days. The hematological parameters of control crabs and crabs exposed to varied doses of acidified water indicated a marked reduction. Significant (p<0.05) higher alkaline phosphatase and albumen were obtained in pH 4.0, 5.0 and 6.0 compared to control; other values were mostly similar to control. The highest superoxide dismutase (SOD) (252.61±0.06 min/mg pro) was recorded in control group, while highest CAT activity (2.08±0.16 min/mg protein) was recorded in crabs exposed to pH 4 treatment. Furthermore, the control group’s SOD activity was significantly higher than the exposed groups. With a lower pH, the quantities of malondialdehyde increased substantially and were significantly different from the control group. While these findings demonstrate that changes in pH have limited impact on energy use, decreasing immune system conditions show that C. armatum is susceptible to pH variations and may be influenced in aquaculture, where a pH drop is more prominent.

Continue reading ‘Effects of water acidification on immune responses of the gercacinid,
Cardiosoma armatum (Herklots, 1851)’

Climate change effects on the ecophysiology and ecological functioning of an offshore wind farm artificial hard substrate community

Highlights

  • Local effects of offshore wind farms add to and interact with global climate change.
  • Species-specific effects on artificial hard substrate colonising community.
  • Mortality, feeding and metabolism generally increased with temperature and lower pH.
  • Temperature and pH had antagonistic effect on growth.
  • Maximised cumulative clearance potential significantly increased by climate change.

Abstract

In the effort towards a decarbonised future, the local effects of a proliferating offshore wind farm (OWF) industry add to and interact with the global effects of marine climate change. This study aimed to quantify potential ecophysiological effects of ocean warming and acidification and to estimate and compare the cumulative clearance potential of suspended food items by OWF epifauna under current and future climate conditions. To this end, this study combined ecophysiological responses to ocean warming and acidification of three dominant colonising species on OWF artificial hard substrates (the blue mussel Mytilus edulis, the tube-building amphipod Jassa herdmani and the plumose anemone Metridium senile). In general, mortality, respiration rate and clearance rate increased during 3- to 6-week experimental exposures across all three species, except for M. senile, who exhibited a lower clearance rate in the warmed treatments (+3 °C) and an insensitivity to lowered pH (−0.3 pH units) in terms of survival and respiration rate. Ocean warming and acidification affected growth antagonistically, with elevated temperature being beneficial for M. edulis and lowered pH being beneficial for M. senile. The seawater volume potentially cleared from suspended food particles by this AHS colonising community increased significantly, extending the affected distance around an OWF foundation by 9.2% in a future climate scenario. By using an experimental multi-stressor approach, this study thus demonstrates how ecophysiology underpins functional responses to climate change in these environments, highlighting for the first time the integrated, cascading potential effects of OWFs and climate change on the marine ecosystem.

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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.

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

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