Greenhouse gas emissions from land-use change, fossil fuel, agriculture, transportation, and electricity sectors expose marine ecosystems to overlapping environmental stressors. Existing climate vulnerability assessment methods analyze the frequency of extreme conditions but often minimally consider how environmental data gaps hinder assessments. Here, we show an approach that assesses vulnerability and the uncertainty introduced by monitoring data gaps, using a case study of ocean acidification and deoxygenation in coastal California. We employ 5 million publicly available oceanographic observations and existing studies on species responses to low pH, low oxygen conditions to calculate vulnerability for six ecologically and economically valuable benthic invertebrate species: red sea urchin (Mesocentrotus franciscanus), purple sea urchin (Strongylocentrotus purpurpatus), warty sea cucumber (Apostichopus parvimensis), pink shrimp (Pandalus jordani), California spiny lobster (Panulirus interruptus), and Dungeness crab (Metacarncinus magister). Further, we evaluate the efficacy of current monitoring programs by examining how data gaps heighten associated uncertainty. We find that most organisms experience low oxygen (<35% saturation) conditions less frequently than low pH ( < 7.6) conditions. It is only deeper dwelling (>75 m depth) life stages such as Dungeness crab adults and pink shrimp embryos, juveniles, and adults that experience more frequent exposure to low oxygen conditions. Adult Dungeness crabs experience the strongest seasonal variation in exposure. Though these trends are intriguing, exposure remains low for most species despite well-documented pH and oxygen declines and strengthening upwelling in the central portions of the California Current. Seasonal biases of data collection and sparse observations near the benthos and at depths where organisms most frequently experience stressful conditions undermine exposure estimates. Herein we provide concrete examples of how pink shrimp and Dungeness crab fisheries may be impacted by our findings, and provide suggestions for incorporating oceanographic data into management plans. By limiting our scope to California waters and assessing the limitations presented by current monitoring coverage, this study aims to provide a granular, actionable framework that policymakers and managers can build from to prioritize targeted enhancements and sustained funding of oceanographic monitoring recommendations.
Continue reading ‘Assessing benthic invertebrate vulnerability to ocean acidification and de-oxygenation in California: the importance of effective oceanographic monitoring networks’Posts Tagged 'crustaceans'
Assessing benthic invertebrate vulnerability to ocean acidification and de-oxygenation in California: the importance of effective oceanographic monitoring networks
Published 21 February 2025 Science ClosedTags: biological response, chemistry, crustaceans, echinoderms, fisheries, methods, multiple factors, oxygen, policy, review
The effects of combined stress from pH and microplastic-derived odours on the European green crab Carcinus maenas’s olfactory behaviour
Published 12 February 2025 Science ClosedTags: biological response, crustaceans, laboratory, North Atlantic, performance
Simple Summary
The European shore crab, Carcinus maenas, also known as the European green crab, uses its sense of smell to detect prey, predators, and mating partners. Here, we examined how such crabs behave in environmental conditions that simulate the changes predicted by climate change. Crabs were exposed to female sexual odours, food smells, and various types of plastic leach outs. A decreased pH altered the crab’s behaviour towards food (Glutathione) and sex odour, reducing the animal’s response levels and increasing reaction times. Most interestingly, the crabs were more attracted to polyethylene (PE) odour in future ocean conditions, whilst males’ responses to female sex cues were especially reduced significantly. Response-level changes vary between the sexes, highlighting that understanding the effects of climate conditions on animal behaviour and choices is complicated and difficult to predict. That crabs become more attracted to plastic raises the question of what the bioactive chemicals are in PE that induce such a response, and this could demonstrate how climate change potentially increases the risks associated with plastic pollution in future oceans.
Abstract
Ocean acidification (OA) associated with climate change is expected to lower the ocean’s pH by 0.5 units by 2100. Whilst associated effects such as coral bleaching and shell calcification are well documented, lesser-known impacts are the ‘invisible’ effects on animal sensory systems. Olfactory disruption impacts the behaviour towards chemical cues in many marine species, including crustaceans. We examine the effects of microplastic odour and additional stressors on the European green crab C. maenas. Using uridine diphosphate (UDP) and uridine triphosphate (UTP) as a sex pheromone bouquet, glutathione (GSH) as a food cue, and polyethylene (PE) as plastic odour, cues were mixed with carboxycellulose to create slow-release gels. Crabs were exposed to gels in seawater pH values of 8.2, 7.6, and 7.2. Crabs took longer to react to all odours in reduced pH conditions (pH 8.2 to pH 7.2, p = 0.0017). At a low pH, PE-exposed crabs exhibited attraction towards microplastic odour and changed behavioural responses by burying. The study confirms low pH as disruptive to olfaction and highlights that plastic derivatives can become more bioactive at reduced pH levels, potentially increasing the threat posed by microplastic pollution. Further research is required to determine the potential long-term impacts of the combined threat of microplastics and reduced pH in the environment.
Continue reading ‘The effects of combined stress from pH and microplastic-derived odours on the European green crab Carcinus maenas’s olfactory behaviour’Behavioral and physiological effects of ocean acidification on juvenile American lobsters (Homarus americanus)
Published 12 February 2025 Science ClosedTags: biological response, crustaceans, laboratory, North Atlantic, performance, physiology
Alteration of pH within the world’s ocean, or ocean acidification (OA), results from increased absorption of CO2 into global waters. Acidification can positively or negatively affect physiology and behavior of marine taxa, though the effects vary greatly based on species and life stage. Crustaceans are often noted as being resilient to acidification, though negative physiological and behavioral impacts have been shown. Studies on the impacts of OA on the American lobster (Homarus americanus) have primarily focused on its physiology. This thesis aims to observe the potential effects of acidification on the foraging behavior and hemolymph chemistry of juvenile American lobsters. We exposed 28 juvenile lobsters (carapace length, CL, 29mm – 52mm, average 42 +/- 1.3mm) to randomly assigned, individual pH values between 7.3 and 7.8 for 12 days to observe potential impacts of acidification. The time taken to locate blue mussels, the number of foraging trips taken, the time taken to successfully feed, and hemolymph L-lactate concentration (stress indicator) were assessed after the exposure period. Counter to our predictions, as pH decreased, lobsters successfully fed two-times quicker, maintained normal locate times of prey, and took fewer foraging trips. We found that lobsters responsed to prey cues similarly across the pH range, indicating that olfaction was likely not impaired. These results suggest that juvenile American lobsters may increase foraging activity in response to acidified conditions.
Continue reading ‘Behavioral and physiological effects of ocean acidification on juvenile American lobsters (Homarus americanus)’Investigating the effects of environmental stress on coastal zooplankton populations: from mechanistic drivers to trophic impacts
Published 29 January 2025 Science ClosedTags: abundance, biological response, BRcommunity, crustaceans, field, laboratory, mortality, multiple factors, otherprocess, oxygen, performance, zooplankton
Environmental stressors, such as hypoxia and acidification, are increasing in intensity, duration, and extent in coastal waters and estuaries. Environmental stressors are known to affect a wide range of marine species, including zooplankton. Zooplankton are a critical link in marine food webs, connecting phytoplankton to higher trophic levels such as economically important fish, and are thought to be informative indicators of ecosystem change. For this reason, increased attention has been paid to understanding the mechanisms shaping zooplankton populations. Previous studies have shown that zooplankton exhibit both lethal and sublethal responses to changes in dissolved oxygen and pH. However, there is a range of species-specific responses to stressors. Different responses across species alter zooplankton community composition and spatial distributions, directly impacting predator-prey interactions and the trophic dynamics in coastal environments. This dissertation integrates laboratory experiments, in situ observations, and field work to understand how environmental stressors affect coastal zooplankton populations and nearshore food webs. In Chapter 1, I conducted laboratory experiments to investigate whether the copepod, Calanus pacificus, showed behavioral responses to stressors, and whether these responses lead to changes in vertical population distributions. Our laboratory experiments demonstrated significant effects of bottom water hypoxia and acidification on behavioral avoidance, swimming statistics, and apparent mortality rates in C. pacificus. In Chapter 2, I used a remote camera system to quantify in situ behavioral responses of zooplankton to stressors, using results from Chapter 1 to generate hypotheses about observations in the field. Our in situ videos revealed that copepods in stressful conditions exhibited significantly slower swimming speeds than copepods in non-stressful conditions, while amphipods showed significantly decreased abundances within stressful conditions. Finally, in Chapter 3, I collected zooplankton net tows in an intertidal estuary to investigate the transport of pelagic species into eelgrass beds and the role of eelgrass beds as potential sinks of pelagic zooplankton over the tidal cycle, potentially due to predation by juvenile fish. We found evidence of transport of pelagic species into intertidal habitats and measured large spatial and temporal variability, highlighting the need for sampling programs that can capture small-scale variability. This dissertation provides insight into the mechanisms that link the effects of environmental stressors across individual responses to population, community, and ecosystem level scales and suggests novel methodologies to help advance our understanding of changing zooplankton dynamics.
Continue reading ‘Investigating the effects of environmental stress on coastal zooplankton populations: from mechanistic drivers to trophic impacts’Ocean acidification may contribute to recruitment failure for Bering Sea red king crab
Published 29 January 2025 Science ClosedTags: biological response, crustaceans, fisheries, individualmodeling, modeling, North Pacific, reproduction
We used semi-parametric Bayesian regression to determine whether ocean acidification or climate warming could explain declining productivity for southeast Bering Sea red king crab (Paralithodes camtchaticus). Negative effects of acidification explained ~21% of recruitment variability over 1980-2023, and ~45% since 2000. Ocean warming had a negligible effect in our analysis. Model-estimated annual mean bottom pH in the region has fallen from ~8.03 in 1980 to ~7.89 in 2023, approaching levels that reduce juvenile survival in laboratory studies. Improved model validation and better understanding of potential threshold effects on red king crab are needed to better understand the possible population-level acidification effect that we demonstrate.
Continue reading ‘Ocean acidification may contribute to recruitment failure for Bering Sea red king crab’Impacts of climate change on members of shallow water Antarctic communities
Published 16 January 2025 Science ClosedTags: algae, Antarctic, biological response, BRcommunity, community composition, crustaceans, laboratory, mortality, otherprocess, performance, physiology
Human-derived CO2 emissions have lowered the ocean’s pH and increased global temperatures. Low seawater pH can decrease the calcification, growth, and survival of calcifying invertebrates. Furthermore, low pH changes macroalgal growth and stress, possibly altering palatability to consumers. Global warming has decreased sea ice coverage, profoundly influencing photosynthetic organisms by altering subsurface irradiance. Shallow, hard-bottom communities along the Western Antarctic Peninsula are characterized by large macroalgal forests that shelter large numbers of mesograzers. Amphipods and macroalgae have a community-wide mutualistic relationship where macroalgae provide refuge from predatory fish while amphipods remove competing epiphytes. To understand how climate change could impact members of this relationship, macroalgal-associated mesograzers were collected near Palmer Station, Antarctica (64°46′S, 64°03′W) and maintained under three different pH treatments [ambient (pH 8.1), near-future (pH 7.7), and distant-future conditions (pH 7.3)] for 52 days. Total assemblage number and the relative proportion of each species were similar across the treatments, indicating possible resistance to short-term low pH exposure. The amphipods Djberboa furcipes, Gondogeneia antarctica, and Prostebbingia gracilis were maintained under the pH treatments for 8 weeks. No difference in biochemical composition or survival was found between the treatments for any of the species. However, each species decreased molt activity between the ambient and pH 7.3 treatment. These results suggest that amphipods may maintain their survival in decreased pH by reallocating energy into compensatory behaviors and away from energy-expensive processes like molting. The palatability of the unpalatable Desmarestia menziesii and the palatable Palmaria decipiens were maintained under three pH treatments and then presented to the amphipod Gondogeneia antarctica in a feeding choice assay. Decreased seawater pH generally lowered the consumption of both species, suggesting that acidification may decrease the palatability of these macroalgae to consumers. Finally, biochemical composition, carbon and nitrogen percentages, and C:N were correlated with sea ice indices for the macroalgae D. menziesii, Himantothallus grandifolius, Sarcopeltis antarctica, and Iridaea sp. from a sea ice gradient. Surprisingly, most of the chemical components were not correlated with sea ice cover, indicating sea ice coverage does not change the nutritional contributions of macroalgae to food webs.
Continue reading ‘Impacts of climate change on members of shallow water Antarctic communities’Future climate change scenarios of increased CO2 and temperature strongly affect a coral reef meiobenthic harpacticoid (Crustacea) community
Published 15 January 2025 Science ClosedTags: biological response, BRcommunity, community composition, crustaceans, laboratory, morphology, mortality, multiple factors, otherprocess, South Atlantic, temperature, zooplankton
Small metazoans, especially harpacticoid copepods, are an important component in the benthic food webs of benthic environments. However, studies on the effects of elevated CO2 and temperature on these animals are scarce and those that do exist focus mainly on the individual species level. A laboratory experiment was conducted to evaluate the impact of different climate change scenarios on a community of harpacticoid copepods from a coral reef environment. Samples were collected from the coral reef subtidal zone of Serrambi beach (Ipojuca, Pernambuco, Brazil), using colonized artificial substrate units. The units were exposed to control treatments and to three climate change scenarios and were collected after 14 and 29 days. A highly diverse community of harpacticoids was analyzed [H′(log2) = 4.37]. Changes in the community structure were observed, and the response of the copepod community structure to the different scenarios varied according to the sampling period. The maintenance of a highly diverse community enabled a complex pattern of responses to be observed at a species level with three different response patterns to the changing seawater conditions: sensitive species represented by Tisbe sp., Stenhelia sp. and Ameira sp.; mildly sensitive represented by Cyclopoida and Dactylopusia sp.; resistant or opportunist represented by Ectinosoma sp.1, Ectinosoma sp.2 and Mesochra sp. The increase in malformed adult animals in the most severe scenario indicated that species that do not suffer mortality are not exempt from sublethal symptoms. Harpacticoid organisms are shown as reliable tools to assess climate change in coral reef environments.
Continue reading ‘Future climate change scenarios of increased CO2 and temperature strongly affect a coral reef meiobenthic harpacticoid (Crustacea) community’Effect of CO2 driven seawater acidification on survival, growth, amino acid and fatty acid levels in the edible shrimp Litopenaeus vannamei
Published 13 January 2025 Science ClosedTags: biological response, crustaceans, growth, laboratory, mortality, physiology
Highlights
- Survival and growth of L. vannamei were declined in OA exposures
- Essential and nonessential amino acids were decreased in shrimps under OA
- Vital unsaturated fatty acids were improved in shrimps under OA conditions
Abstract
Acidification in the ocean environment is considered a worldwide problem that drives serious consequences for organisms. The current investigation was focused to study the effect of CO2 induced ocean acidification (OA) on the survival, growth, and composition of amino acids and fatty acids in the shrimp Litopenaeus vannamei. A seven weeks OA experiment was conducted on the shrimp groups with different pH such as 8.2 (control), 7.8, 7.6, 7.4, 7.2, and 7.0. A considerable decline in survival, growth, essential and nonessential amino acids, and saturated fatty acids in shrimps under OA exposures (pH 7.8 to 7.0). In this context, a notable improvement in amino acids (histidine, alanine, and cysteine) and fatty acids (palmitoleic acid, linoleic acid, linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid) in L. vannamei reared under acidified seawater environments suggests that the high demand for these amino acids and fatty acids to tolerate the acidic stress.
Continue reading ‘Effect of CO2 driven seawater acidification on survival, growth, amino acid and fatty acid levels in the edible shrimp Litopenaeus vannamei’Microplastic hotspots mapped across the Southern Ocean reveal areas of potential ecological impact
Published 9 January 2025 Science ClosedTags: Antarctic, biological response, chemistry, crustaceans, phytoplankton, review, zooplankton
Marine microplastic is pervasive, polluting the remotest ecosystems including the Southern Ocean. Since this region is already undergoing climatic changes, the additional stress of microplastic pollution on the ecosystem should not be considered in isolation. We identify potential hotspot areas of ecological impact from a spatial overlap analysis of multiple data sets to understand where marine biota are likely to interact with local microplastic emissions (from ship traffic and human populations associated with scientific research and tourism). Then we account for cumulative effects by identifying which areas with potential elevated microplastic-biota interaction are already subject to climate change related stresses (ocean warming and acidification). Our analysis indicates that biologically productive coastal areas in proximity to populated facilities are where microplastics pose most risk to the ecosystem, and that the northern Antarctic Peninsula is likely to be the main risk hotspot. This study is the first to map the threat of microplastics to the Southern Ocean ecosystem in a multi-stressor context, locating where microplastic monitoring programmes and mitigation measures may be considered a matter of urgency.
Continue reading ‘Microplastic hotspots mapped across the Southern Ocean reveal areas of potential ecological impact’Toxicity of PAHs-enriched sediments on meiobenthic communities under ocean warming and CO2-driven acidification scenarios
Published 6 January 2025 Science ClosedTags: annelids, biological response, BRcommunity, community composition, crustaceans, laboratory, mollusks, multiple factors, nematodes, otherprocess, platyhelminthes, sediment, South Atlantic, tardigrada, temperature, toxicants, zooplankton
Highlights
- Temperature rise reduced the densities of Copepoda and certain Nematoda groups.
- CO2 acidification prevented some Nematoda groups from increasing at high temperatures.
- CO2 acidification reduced Copepoda and nauplii densities, but increased Ostracoda.
- Complex interactions increased certain meiobenthic groups exposed to sediment PAHs.
- Global change and pollution showed interactive effects in meiobenthic communities.
Abstract
This study aimed to assess the interactive effects of CO2-driven acidification, temperature rise, and PAHs toxicity on meiobenthic communities. Laboratory microcosms were established in a full factorial experimental design, manipulating temperature (25 °C and 27 °C), pH (8.1 and 7.6), and PAH contamination (acenaphthene + benzo(a)pyrene spiked sediments and negative control). Temperature rise and CO2-driven acidification led to a decrease in the densities of Copepoda. The density of nematodes Pseudochromadora and Daptonema also decreased, while Sphaerotheristus and Sabatieria densities increased, particularly in the absence of CO2-driven acidification. Ostracoda densities increased in the acidified scenario. PAH contamination resulted in decreased Daptonema densities but increased Turbellaria and certain Nematoda genera (e.g. Pseudochromadora). Overall, the results indicate that the changes of meiobenthic communities caused by CO2 acidification, warming, and PAH contamination are shaped by the vulnerability and tolerance of each taxonomic group, alongside indirect effects observed in Nematoda assemblages.
Continue reading ‘Toxicity of PAHs-enriched sediments on meiobenthic communities under ocean warming and CO2-driven acidification scenarios’Temperature, pH, and diet interactively affect biosynthesis of polyunsaturated fatty acids in a benthic harpacticoid copepod
Published 3 January 2025 Science ClosedTags: biological response, crustaceans, laboratory, multiple factors, physiology, temperature, zooplankton
Greenhouse gas emissions lead to ocean warming and acidification, negatively impacting marine organisms and their functioning, including long-chain polyunsaturated fatty acid (LC-PUFA) production by marine microalgae. Copepods, primary consumers of microalgae, possess a unique capacity for endogenous LC-PUFA biosynthesis, possibly enabling them to cope with reduced dietary LC-PUFA availabilities. However, this capacity may be itself impacted by changing oceanographic conditions. In this study, we conducted a laboratory experiment to evaluate the combined effects of warming (+3°C), acidification (−0.4 pH), and dietary LC-PUFA deficiency on the fatty acid composition and LC-PUFA biosynthesis (measured by quantitative RT-PCR) of the benthic harpacticoid copepod Platychelipus littoralis (Brady, 1880). We hypothesized increased LC-PUFA biosynthesis under all drivers compensating for LC-PUFA reductions. Lipid profiles of copepods exposed to multiple stressors contained shorter-chained and more saturated fatty acids. While copepods maintained base-line relative concentrations of the physiologically important LC-PUFA docosahexaenoic acid (DHA) on an LC-PUFA deficient diet at ambient temperatures, DHA concentrations decreased significantly with higher temperatures. Expression of the DHA biosynthesis genes Δ4 front-end desaturase and elovl1a increased under dietary LC-PUFA deficiency but did not exceed base-line levels when simultaneously exposed to acidification. Expression of Δ4 front-end desaturase and multiple elongases correlated positively with C18 precursor concentrations and negatively with those of LC-PUFAs such as DHA, indicating their role as LC-PUFA biosynthesis enzymes. Overall, our findings suggest that ocean warming and acidification may impede benthic copepods’ LC-PUFA biosynthesis capacity under reduced dietary inputs, limiting their contribution toward global LC-PUFA availability for higher trophic levels.
Continue reading ‘Temperature, pH, and diet interactively affect biosynthesis of polyunsaturated fatty acids in a benthic harpacticoid copepod’Local effects of Sargassum beds on the seawater carbonate system and plankton community
Published 30 December 2024 Science ClosedTags: biological response, BRcommunity, chemistry, crustaceans, field, mitigation, North Pacific, phanerogams, phytoplankton, zooplankton
Highlights
- The ecological effect of the sargassum beds depends on seaweed biomass.
- The biomass of the sargassum beds in Weizhou Island reached its peak in spring.
- Sargassum beds significantly influenced the carbonate system and DOC pool in spring.
- Sargassum beds is more likely to alter phytoplankton communities than zooplankton.
Abstract
Sargassum beds are recognized as important habitats for fostering species diversity and capturing blue carbon, exerting significant influence on seawater chemistry and planktonic communities. However, there is still much to uncover about the interactions between these biogenic habitats and seawater chemistry, as well as their impact on plankton communities in the water column. To address this gap, we conducted a study on the functions of natural Sargassum beds in various seasons around the northern part of Weizhou Island in the South China Sea. Our research involved quantifying carbonate chemistry, carbon stock potential, and seawater plankton communities in two distinct areas: the core area in the interior regions of the seaweed beds and the non-core areas at its periphery or external. Our findings revealed an estimated 3.7 km2 of benthic Sargassum, with an overall biomass of 21.2 Gg km−2, reaching its peak productivity in spring, equivalent to 1.14 Pg C km−2. Notably, during spring, the seaweed beds significantly influenced the exchange of CO2 at the air-sea interface, leading to reduced pCO2 (41 μatm) in the core area compared to the non-core area (p < 0.05), thus enhancing the local carbon sequestration capacity. Additionally, we observed significant regional differences in the concentration of dissolved organic carbon (DOC) only during the spring season, indicating the capacity of Sargassum to alter the DOC pool around its habitat. We anticipate that seaweed deposition will become a more frequent occurrence towards the end of the growth period, with increasing fragments facilitating a transition towards phytoplankton-dominated marine ecosystems. Furthermore, the fixation of extra CO2 by seaweed may lead to a pH increase, providing a refuge for copepods from ocean acidification. In summary, our observations suggest that the Sargassum beds plays a substantial role in nearshore carbon cycling and ecological impact, surpassing previous documentation.
Continue reading ‘Local effects of Sargassum beds on the seawater carbonate system and plankton community’Ocean warming and acidification alter calcification and innate immune system gene expression in juvenile American lobsters, Homarus americanus
Published 27 December 2024 Science ClosedTags: biological response, crustaceans, laboratory, molecular biology, multiple factors, North Atlantic, temperature
Highlights
- Ocean warming and acidification affect gene expression in juvenile lobsters.
- De novo trascriptome used to assess gene expression and functional enrichment.
- Calcification and cuticle genes increased expression with warming and acidification.
- Innate immune system genes trended toward downregulation.
- Lobsters may be more vulnerable to injury or disease due to climate change.
Abstract
The Gulf of Maine, home to American lobster, Homarus americanus, is experiencing rapid ocean warming (OW) and acidification (OA) due to climate change. While some studies have investigated the effects of either ocean acidification (OA) or warming (OW) on lobsters, few explore the interaction of these stressors, particularly on gene expression. We evaluated the effects of OA and OW on early benthic juvenile lobster transcriptomics using RNA sequencing and RT-qPCR through two distinct aquarium experiments. Lobsters were reared under OW/OA conditions aligned with values predicted for 2100: decrease in pH by 0.3–0.4 units; mean sea surface warming of 2.89 °C. RNA was isolated from carapace hypodermal tissue in both experiments. The multi-stressor treatment in the RNAseq experiment had the greatest differential expression. Genes of interest pertaining to calcification and cuticle development were primarily downregulated under high temperature but upregulated under acidified and multi-stressor conditions. In the RT-qPCR experiment, crustin alone was significantly downregulated and only under the most extreme multi-stressor treatment. This gene along with the prophenoloxidase activating enzyme had expression that trended toward downregulation across all treatments, suggesting a possible correlation to immune suppression. Expression profiles for crustin and the calcification gene, carbonic anhydrase differed across treatments based on molt cycle timing, indicating that stressor impacts may vary depending on the molt cycle phase. Elevated temperature had a greater effect on the expression of calcification and cuticle development genes, though the direction of expression reversed with multiple stressors. These results indicate the impacts of OW and OA on early benthic juvenile lobsters are complex, possibly synergistic, vary with molt cycle, and potentially interfere with normal cuticle development, which may increase susceptibility to injury or disease.
Continue reading ‘Ocean warming and acidification alter calcification and innate immune system gene expression in juvenile American lobsters, Homarus americanus’Climate covariate choice and uncertainty in projecting species range shifts: a case study in the Eastern Bering Sea
Published 26 December 2024 Science ClosedTags: Arctic, biological response, crustaceans, field, fish, fisheries, modeling, multiple factors, oxygen, regionalmodeling, temperature
Species distribution models (SDMs) are critical to the adaptive management of fisheries under climate change. While many approaches projecting marine species range shifts have incorporated the effects of temperature on movement, there is a need to incorporate a wider suite of ecologically relevant predictors as temperature-based SDMs can considerably under- or over-estimate the rate of species responses to climate shocks. As a subarctic ecosystem at the sea ice margin, the Eastern Bering Sea (EBS) is warming faster than much of the global ocean, resulting in the rapid redistribution of key fishery and subsistence resources. To support long-term planning and adaptation, we combine 40 years of scientific surveys with a high-resolution oceanographic model to examine the effects of bottom temperature, oxygen, pH and a regional climate index (the extent of the EBS ‘cold pool’) on range projections through the end of the century. We use multimodel inference to partition uncertainty among earth systems models, climate scenarios and distribution model parameterizations for several ecologically and economically important EBS groundfish and crabs. Covariate choice is the primary source of uncertainty for most species, with models that account for spatial responses to the cold pool performing better and suggesting more extensive northward movements than alternative models. Models suggest declines in the probability of occurrence at low pH and oxygen concentrations for most species. We project shifts that are directionally consistent with, yet larger than those previously estimated for most species, suggesting that accounting for large-scale climate variability in species distribution models may substantially alter range projections.
Continue reading ‘Climate covariate choice and uncertainty in projecting species range shifts: a case study in the Eastern Bering Sea’Will climate change alter the swimming behavior of larval stone crabs?: a guided-inquiry lesson
Published 23 December 2024 Science ClosedTags: biological response, crustaceans, education, multiple factors, performance, reproduction, temperature
The ocean has absorbed ~one third of the excess atmospheric carbon dioxide (CO2) released since the Industrial Revolution. When the ocean absorbs excess CO2, a series of chemical reactions occur that result in a reduction in seawater pH, a process called ocean acidification. The excess atmospheric CO2 is also resulting in warmer seawater temperatures. These stressors pose a threat to marine organisms, especially during earlier life stages (i.e., larvae). The larvae of species like the Florida stone crab (Menippe mercenaria) are free swimming, allowing a population to disperse and recruit into new habitats. After release, stone crab larvae undergo vertical swimming excursions in response to abiotic stimuli (gravity, light, pressure) allowing them to control their depth. Typically, newly hatched larvae respond to abiotic cues that would promote a shallower depth distribution, where surface currents can transport them offshore to complete development. As larvae develop offshore, they become less sensitive to certain abiotic stimuli, which promotes a deeper depth distribution that may expose them to variable current speeds, thus influencing the direction of advection (horizontal movement). Environmental stressors like ocean acidification and elevated seawater temperatures may also impact the larvae’s natural response to these abiotic stimuli throughout ontogeny (development). Changes in their natural swimming behavior due to climate stressors could, therefore, influence the transport and dispersal of the species. This guided-inquiry lesson challenges introductory marine biology and oceanography students to determine how future ocean pH and temperature projections could impact the swimming behavior of Florida stone crab larvae.
Continue reading ‘Will climate change alter the swimming behavior of larval stone crabs?: a guided-inquiry lesson’The effects of ocean acidification on the olfactory system of the yellow shore crab, Hemigrapsus oregonensis
Published 27 November 2024 Science ClosedTags: biological response, crustaceans, laboratory, molecular biology, North Pacific, performance, physiology
Increases in atmospheric carbon dioxide (CO2) lead to ocean acidification (OA) which has been shown to alter olfactory behaviours in marine organisms. However, coastal regions experience CO2 levels greater than end-of-century open ocean predictions. I investigated the effects of OA on the olfactory system of the intertidal yellow shore crab, Hemigrapsus oregonensis. I hypothesized that given their variable natural environment these crabs are more tolerant to OA. Crabs demonstrated impaired olfactory behaviour after acute and long-term static exposures to OA. This impairment was correlated with a decrease in olfactory receptor protein expression and a 20% decrease in olfactory sensory neuron volume. Crabs exposed to fluctuating CO2 had intermediate behavioural responses and showed no changes in receptor expression. These results show that coastal crabs are affected by ocean acidification despite their variable natural environment, being particularly vulnerable during upwelling events and this impairment will likely worsen in the future.
Continue reading ‘The effects of ocean acidification on the olfactory system of the yellow shore crab, Hemigrapsus oregonensis’Ocean acidification thresholds for decapods are unresolved
Published 26 November 2024 Science ClosedTags: biological response, crustaceans, methods, mortality, reproduction, review
A published analysis of ocean acidification thresholds for decapod crustaceans highlights data showing the negative effects of low pH on many species. However, the methods used in the paper have substantial flaws that call into question the proposed thresholds. The quantitative metrics calculated for the meta-analysis are uninformative with respect to pH sensitivity, which raises concerns about the validity of the thresholds developed by the expert opinion process. We recommend against using the published thresholds and for a reanalysis of the data to identify new thresholds.
Introduction
Identifying thresholds of biological response to environmental stressors can provide valuable information for marine resource managers (Heinze et al., 2021). In the field of ocean acidification (OA), meta-analysis of species pH exposure experiments have been used to develop thresholds or relative risk metrics for multiple taxa (Bednaršek et al., 2019; Bednaršek et al., 2021b; Hancock et al., 2020; Cornwall et al., 2022). Decapod crustaceans are an important ecological and economic component of marine ecosystems, and species in this group are potentially vulnerable to OA. Using quantitative analysis based on published data from species pH exposure experiments and expert opinion, Bednaršek et al. (2021a) developed pH exposure thresholds for a number of biological responses of decapods. The Bednaršek et al. (2021a) thresholds have been used in other analyses to characterize potential risk of decapod species to OA (Alin et al., 2023; Alin et al., 2024; Hamilton et al., 2023; Zeldis et al., 2022; Siegel et al., 2022). Although there is no doubt that many decapod species are sensitive to elevated CO2 and exhibit thresholds in their sensitivity, the quantitative analysis in Bednaršek et al. (2021a), which informs the expert opinion, has several methodological issues which raise questions about the utility of the recommended thresholds. This brief research report describes the methodological issues and discusses the implications for our current understanding of pH thresholds for decapods. It does not recommend a specific pathway for re-evaluation of the data, but does provide some relevant references that could guide a re-evaluation.
Continue reading ‘Ocean acidification thresholds for decapods are unresolved’Combined effects of low pH stress and bacterial infection on the transcriptional changes of hemocytes in Chinese mitten crab Eriocheir sinensis
Published 6 November 2024 Science ClosedTags: biological response, BRcommunity, crustaceans, laboratory, performance, physiology, prokaryotes
Highlights
- Low pH stress might disturb the maintaining of protein homeostasis in hemocytes.
- Combination of low pH stress and bacterial infection cause disruption of TLR pathway.
- Low pH stress and bacterial infection inhibit the TCA cycle in hemocytes.
Abstract
Water pH is a critical environmental factor for aquaculture. Acidification is a pressing environmental issue that poses significant threats to the aquaculture industry. Since the outbreaks of disease generally accompany with environmental stress, comparative transcriptome analyses were performed to investigate the combined effects of low pH stress and bacterial infection on the transcriptional changes of hemocytes in the economically important crab Eriocheir sinensis. The results revealed that the immune deficiency (IMD) pathway and prophenoloxidase (proPO) system was activated to defense against Vibro parahaemolyticus even when crabs were subjected to low pH stress, whereas low pH stress resulted in the disorder of Toll-like receptor (TLR) pathway upon V. parahaemolyticus infection. Moreover, low pH stress might weaken crabs′ defense against V. parahaemolyticus by inhibiting the up-regulation of crustin and suppressing the expression of lysozyme, and disturb the maintaining of protein homeostasis through the transcriptional decrement of a batch of heat shock proteins (HSPs). It is worth noting that both V. parahaemolyticus infection and low pH stress might suppress the energy metabolism in the hemocytes via inhibiting the expression of critical enzymes, dihydrolipoyllysine-residue acetyltransferase component of pyruvate dehydrogenase complex and fumarase, in the tricarboxylic acid (TCA) cycle. This study provides novel understandings concerning the transcriptional changes of hemocyte in E. sinensis subjected to a combination of low pH stress and V. parahaemolyticus infection as well as contribute to optimize the management strategies for the prevention and control of diseases in E. sinensis farming.
Continue reading ‘Combined effects of low pH stress and bacterial infection on the transcriptional changes of hemocytes in Chinese mitten crab Eriocheir sinensis’Energy budget as a tool to assess the effects of environmental stressors: a study on whiteleg shrimp (Penaeus vannamei) exposed to variations in salinity and ocean acidification
Published 10 October 2024 Science ClosedTags: biological response, crustaceans, growth, laboratory, multiple factors, oxygen, physiology, salinity, temperature
Our goal was to use the energy budget as a tool to evaluate the effects of salinity (20, 25, 30, 35 or 40‰) and ocean acidification (pH 8.0 or 7.3) in Penaeus vannamei. We assessed the energy budget a range of physiological processes (ingestion, defecation, growth, metabolism, excretion, energy substrate, hepatosomatic index, and osmoregulation). In general, salinity had an accentuated effect than pH, as it altered nearly all physiological parameters, including the energy channeled into growth (up to −56%). Reduced pH also affected the energy budget: increased energy lost in feces (25 and 40‰: +21% and 13%, respectively), excretion (25‰: +55%), and metabolism (20‰: +58%). Furthermore, acidified pH increased oxygen consumption by 60%, which may be related to higher energy expenditure. In conclusion, the energy budget can be a valuable tool for assessing the impacts of environmental stressors and the salinity has an accentuated effect than the ocean acidification predicted.
Continue reading ‘Energy budget as a tool to assess the effects of environmental stressors: a study on whiteleg shrimp (Penaeus vannamei) exposed to variations in salinity and ocean acidification’
