Dungeness crab (Metacarcinus magister) have significant socioeconomic value, but are threatened by ocean acidification (OA) and other environmental stressors that are driven by climate change. Despite evidence that adult harvests are sensitive to the abundance of larval populations, relatively little is known about how Dungeness megalopae will respond to these stressors. Here we evaluate the ability to use micro-computed tomography (μCT) to detect variations in megalope exoskeleton density and how these measurements reflect environmental variables and calcification mechanisms. We use a combination of field data, culture experiments, and model simulations to suggest resolvable differences in density are best explained by minimum pH at the time zoeae molt into megalopae. We suggest that this occurs because more energy must be expended on active ion pumping to reach a given degree of calcite supersaturation at lower pH. Energy availability may also be reduced due to its diversion to other coping mechanisms. Alternate models based on minimum temperature at the time of the zoea-megalope molt are nearly as strong and complicate the ability to conclusively disentangle pH and temperature influences. Despite this, our results suggest that carryover effects between life stages and short-lived extreme events may be particularly important controls on exoskeleton integrity. μCT-based estimates of exoskeleton density are a promising tool for evaluating the health of Dungeness crab populations that will likely provide more nuanced information than presence-absence observations, but future in situ field sampling and culture experiments are needed to refine and validate our results.
Continue reading ‘Evaluating environmental controls on the exoskeleton density of larval Dungeness crab via micro computed tomography’Posts Tagged 'crustaceans'
Evaluating environmental controls on the exoskeleton density of larval Dungeness crab via micro computed tomography
Published 16 March 2023 Science Leave a CommentTags: biological response, crustaceans, field, individualmodeling, laboratory, modeling, morphology, North Pacific, reproduction
Nanoplastics induce epigenetic signatures of transgenerational impairments associated with reproduction in copepods under ocean acidification
Published 15 March 2023 Science Leave a CommentTags: biological response, crustaceans, laboratory, molecular biology, multiple factors, North Pacific, reproduction, toxicants, zooplankton
Ocean acidification (OA) is one of many major global climate changes that pose a variety of risks to marine ecosystems in different ways. Meanwhile, there is growing concern about how nanoplastics (NPs) affect marine ecosystems. Combined exposure of marine organisms to OA and NPs is inevitable, but their interactive effects remain poorly understood. In this study, we investigated the multi- and transgenerational toxicity of NPs on copepods under OA conditions for ten generations. The findings revealed that OA and NPs have a synergistic negative effect on copepod reproduction across generations. In particular, the transgenerational groups showed reproductive impairments in the F1 and F2 generations (F1T and F2T), even though they were never exposed to NPs. Moreover, our epigenetic examinations demonstrated that the observed intergenerational reproductive impairments are associated with differential methylation patterns of specific genes, suggesting that the interaction of OA and NPs can pose a significant threat to the sustainability of copepod populations through epigenetic modifications. Overall, our findings provide valuable insight into the intergenerational toxicity and underlying molecular mechanisms of responses to NPs under OA conditions.
Continue reading ‘Nanoplastics induce epigenetic signatures of transgenerational impairments associated with reproduction in copepods under ocean acidification’The multi-generational effect of seawater acidification on larval development, reproduction, ingestion rate, and ATPase activity of Tigriopus japonicus Mori, 1938
Published 13 March 2023 Science Leave a CommentTags: biological response, crustaceans, North Pacific, performance, physiology, reproduction, zooplankton
Ocean acidification threatens marine organisms continuously. To ascertain if adaptation of marine species to ocean acidification enhanced over multiple generations, we studied the transgenerational effects of ocean acidification on the development, reproduction, ingestion rate, and ATPase activity of a copepod Tigriopus japonicus Mori, 1938. In the first mode, individuals were exposed to either one of the pH levels (8.1 (control), 7.7, 7.3) for five successive generations. In the second mode, each successive generation was exposed to a lower pH level (pH levels: 8.1, 7.9, 7.7, 7.5, 7.3). After prolonged exposure to a constant seawater acidification level, the capacity to adapt to the stress increased. However, when exposed to seawater of descending pH, the detrimental effects gradually increased. Energy allocated to development and reproduction was reduced although the ingestion rate continued to improve in successive generations. Therefore, ongoing ocean acidification might lower the energy transfer of copepods to higher trophic levels.
Continue reading ‘The multi-generational effect of seawater acidification on larval development, reproduction, ingestion rate, and ATPase activity of Tigriopus japonicus Mori, 1938’Climate change effects on marine species across trophic levels
Published 10 March 2023 Science ClosedTags: biological response, communitymodeling, crustaceans, laboratory, mesocosms, modeling, mollusks, morphology, multiple factors, predation, review, temperature
Climate change and anthropogenic activities are producing a range of new selection pressures, both abiotic and biotic, on marine organisms. While there are numerous studies that have investigated the response of individual marine organisms to climate change, few studies have focused on differences in organismal responses across trophic levels. Such trophic differences in response to climate change may disrupt ecological interactions and thereby threaten marine ecosystem function. In addition, predation is known as a strong driver that impacts individuals and populations. Despite this, we still do not have a comprehensive understanding of how different trophic levels respond to climate change stressors, predation and their combined effects in marine ecosystems.
The main focus of this thesis is to identify whether marine trophic levels respond differently to climatic stressors and predation. To explore these questions, I have used a combination of traditional mesocosm experiments, together with a statistical method called meta-analysis. I initiated the research by study the responses of marine gastropods at two trophic levels to ocean acidification and predation using long-term mesocosm experiments together with a gastropod-specific meta-analyses. I focused on the amount of phenotypic plasticity in morphological traits of snails when exposed to the two stressors. In order to generalise and test these assumptions among a greater number of marine taxa, I used the meta-analysis approach to investigate the effects of ocean acidification and warming, as well as their combined effects on four marine trophic levels. Finally, to study the individual and combined effects of ocean acidification and predation with respect to inducible defences, I again applied a mesocosm experiment and used blue mussels as a model species.
By using long-term mesocosm experiments and the gastropod-specific meta-analysis on marine gastropods from two trophic levels, I showed that these trophic levels varied in their responses to both ocean acidification and predation. Gastropods at lower trophic levels exhibited greater phenotypic plasticity against predation, while those from higher trophic levels showed stronger tolerance to ocean acidification. Next, by using a meta-analysis, including a large number of species and taxa, examining the effects of ocean acidification and warming, I revealed that top-predators and primary producers were most tolerant to ocean acidification compared to other trophic levels. Herbivores on the other hand, were the most vulnerable trophic level against abiotic stress. Again, using the meta-analysis approach, but this time incorporating only factorial experimental data that included the interactive effects of ocean acidification and ocean warming, I showed that higher trophic levels again were the most tolerant trophic level, and herbivores being most sensitive, with respect to the combined effect of the two stressors. Contrary to previous discussions in the literature concerning multiple climate-related stressors, antagonistic and additive effects occurred most frequently, while synergistic effects were less common and which decreased with increasing trophic rank. Finally, by conducting a fully-factorial experiment using blue mussels, I found that mussels with previous experience contact with predator has developed greater inducible defences than ones without previous experience. However, levels of ocean acidification may mask predator cues, or obstruct shell material, and consequently disrupt blue mussels inducible defence from crab predation.
In summary, marine trophic levels respond differently to both biotic and climatic stressors. Higher trophic levels, together with primary producers, were often more robust against abiotic stress and may therefore be better prepared for future oceans compare species from lower trophic levels. These results may provide vital information for: implementing effective climate change mitigation, to understand which stressors to act on, and when and where to intervene for prioritizing conservation actions.
Continue reading ‘Climate change effects on marine species across trophic levels’Ocean acidification-mediated food chain transfer of polonium between primary producers and consumers
Published 7 March 2023 Science ClosedTags: biological response, crustaceans, laboratory, morphology, multiple factors, physiology, phytoplankton, toxicants, zooplankton
Phytoplankton and zooplankton are key marine components that play an important role in metal distribution through a food web transfer. An increased phytoplankton concentration as a result of ocean acidification and warming are well-established, along with the fact that phytoplankton biomagnify 210Po by 3–4 orders of magnitude compared to the seawater concentration. This experimental study is carried out to better understand the transfer of polonium between primary producers and consumers. The experimental produced data highlight the complex interaction between the polonium concentration in zooplankton food, i.e. phytoplankton, its excretion via defecated fecal pellets, and its bioaccumulation at ambient seawater pH and a lower pH of 7.7, typical of ocean acidification scenarios in the open ocean. The mass of copepods recovered was 11% less: 7.7 pH compared to 8.2. The effects of copepod species (n = 3), microalgae species (n = 3), pH (n = 2), and time (n = 4) on the polonium activity in the fecal pellets (expressed as % of the total activity introduced through feeding) was tested using an ANOVA 4. With the exception of time (model: F20, 215 = 176.84, p < 0.001; time: F3 = 1.76, p = 0.16), all tested parameters had an impact on the polonium activity (copepod species: F2 = 169.15, p < 0.0001; algae species: F2 = 10.21, p < 0.0001; pH: F1 = 9.85, p = 0.002) with complex interactions (copepod x algae: F2 = 19.48, p < 0.0001; copepod x pH: F2 = 10.54, p < 0.0001; algae x pH: F2 = 4.87, p = 0.009). The experimental data underpin the hypothesis that metal bioavailability and bioaccumulation will be enhanced in secondary consumers such as crustacean zooplankton due to ocean acidification.
Continue reading ‘Ocean acidification-mediated food chain transfer of polonium between primary producers and consumers’Contrasting behavioural responses to ocean acidification and warming have the potential to disrupt herbivory
Published 24 February 2023 Science ClosedTags: biological response, crustaceans, echinoderms, mollusks, multiple factors, review, temperature
Highlights
- Global climate change has the potential to disrupt herbivore behaviours.
- Current studies emphasise certain locations, life stage, phyla, and behaviours.
- Behavioural experiments on invertebrate herbivores focus on grazing and movement.
- Where there were effects, typically grazing increased while movement decreased.
- Isolated effects of warming and acidification were often restricted when combined.
Abstract
Global change has the potential to affect organisms and re-structure ecosystems where key species interactions, such as herbivory, are disrupted. The fastest ways individual herbivores – and therefore ecosystems – can respond to climate change is through shifts in behaviour. In marine habitats, environmental changes of particular concern in the future are ocean acidification and warming. Consequently, we reviewed the existing literature in this area of research, to identify if there were any over-arching trends or emerging patterns in behavioural responses of marine herbivores to ocean acidification and warming. We identified that while the body of research is growing, focus remains primarily on few locations (temperate areas), phyla (Mollusca, especially gastropods; Crustacea; Echinodermata), and behaviours (grazing rate, movement). Although representing a relatively narrow view of future herbivory, this review indicates that in many cases, the key behaviours of feeding and movement could be maintained under ocean acidification and warming. However, where change is observed, it is more likely grazing will be enhanced and movement impaired. If such patterns were to manifest under future climates, it would mean that the herbivores present would consume more yet there may be less of them as impaired movement and escape behaviours would have made them more vulnerable to predation. The exact responses will, however, likely be context-dependant. Therefore, we recommend future studies address the research gaps our review identified (i.e., a lack of understanding in tropical and polar regions, economically and ecologically important Crustacean and Echinoderm species, early life history stages, and more behavioural responses in addition to feeding and movement). Understanding the diversity of responses expected under varied contexts will be important to uncover trends in how marine invertebrates will behave under global change.
Continue reading ‘Contrasting behavioural responses to ocean acidification and warming have the potential to disrupt herbivory’Morphology and stable isotope ecology of Pleuroncodes planipes adult life stages and their vulnerability to climate change stressors
Published 16 February 2023 Science ClosedTags: biological response, crustaceans, growth, morphology, multiple factors, temperature
Like many in Southern California during the 2015/16 El Niño event, I was struck by the presence of thousands of bright red tuna crabs (Pleuroncodes planipes) abundant at sea and washing ashore. Their sudden prevalence inspired me to learn more about these fascinating animals. Despite drawing so much attention, basic details related to their feeding behaviors and life history remain unknown. P. planipes have long been thought, but never confirmed, to experience a unique life history among crustaceans during which they undergo a sequential habitat shift from pelagic to benthic as adults. In this dissertation research, I applied contemporary methods of stable isotope ecology in combination with ecomorphology to examine aspects of their life history relevant to their pelagic and benthic life stages. We further assessed their vulnerability to the climate change stressors of ocean acidification and ocean warming through a long-term experiment. Through this work, we uncovered morphological differences and an ontogenetic diet shift between pelagic and benthic adult stages as well as significant impacts of temperature, but not pCO2/pH on molting and growth in pelagic adults. These results provide the first evidence in support of the hypothesis that P. planipes adult pelagic and benthic stages are distinct and yield important insight into how this transition could be impacted as the oceans continue to change.
Continue reading ‘Morphology and stable isotope ecology of Pleuroncodes planipes adult life stages and their vulnerability to climate change stressors’Ocean acidification causes fundamental changes in the cellular metabolism of the Arctic copepod Calanus glacialis as detected by metabolomic analysis
Published 23 January 2023 Science ClosedTags: biological response, crustaceans, molecular biology, physiology, zooplankton
Using a targeted metabolomic approach we investigated the effects of low seawater pH on energy metabolism in two late copepodite stages (CIV and CV) of the keystone Arctic copepod species Calanus glacialis. Exposure to decreasing seawater pH (from 8.0 to 7.0) caused increased ATP, ADP and NAD+ and decreased AMP concentrations in stage CIV, and increased ATP and phospho-L-arginine and decreased AMP concentrations in stage CV. Metabolic pathway enrichment analysis showed enrichment of the TCA cycle and a range of amino acid metabolic pathways in both stages. Concentrations of lactate, malate, fumarate and alpha-ketoglutarate (all involved in the TCA cycle) increased in stage CIV, whereas only alpha-ketoglutarate increased in stage CV. Based on the pattern of concentration changes in glucose, pyruvate, TCA cycle metabolites, and free amino acids, we hypothesise that ocean acidification will lead to a shift in energy production from carbohydrate metabolism in the glycolysis toward amino acid metabolism in the TCA cycle and oxidative phosphorylation in stage CIV. In stage CV, concentrations of most of the analysed free fatty acids increased, suggesting in particular that ocean acidification increases the metabolism of stored wax esters in this stage. Moreover, aminoacyl-tRNA biosynthesis was enriched in both stages indicating increased enzyme production to handle low pH stress.
Continue reading ‘Ocean acidification causes fundamental changes in the cellular metabolism of the Arctic copepod Calanus glacialis as detected by metabolomic analysis’A positive temperature-dependent effect of elevated CO2 on growth and lipid accumulation in the planktonic copepod, Calanus finmarchicus
Published 23 December 2022 Science ClosedTags: biological response, crustaceans, laboratory, morphology, multiple factors, North Atlantic, physiology, reproduction, temperature, zooplankton
Calanus finmarchicus were reared from eggs to adults at 12°C and 16°C with non-limiting food in combination with ambient (600 μatm) and high (1100 μatm) pCO2. These conditions are likely to be encountered by the species at the southern margins of its biogeographical range by the end of the century. Dry weight (DW), carbon (C) and nitrogen (N) mass, oil-sac volume (OSV), fatty acid composition (FA), and oxygen consumption rates (OCR) were measured on newly molted stage CV copepodites and recently molted adult females. By focusing our measurements on these precise events in the life cycle, we were able to obtain a more accurate comparison of growth and respiration across treatments. Copepods raised at 12°C had a significantly greater DW, OSV, and C and N mass than those raised at 16°C High pCO2, independent of temperature, was associated with a further increase in the DW and C content of the copepods. Interactive effects of temperature and pCO2 resulted in a larger OSV at low temperature and high pCO2. Mass-specific respiration rates were significantly lower at lower temperatures and elevated pCO2 suggesting that the increase in mass (DW, C, and OSV) resulted from reduced metabolic cost. The composition of fatty acids in the copepods varied mainly with temperature. Two fatty acids varied with pCO2: 16:0 tended to decrease with higher pCO2 and 18:3n−3 tended to increase with higher pCO2. These observations suggest that elevated pCO2/lower pH in future oceans may have a beneficial effect on C. finmarchicus.
Continue reading ‘A positive temperature-dependent effect of elevated CO2 on growth and lipid accumulation in the planktonic copepod, Calanus finmarchicus’Biological responses of the predatory blue crab and its hard clam prey to ocean acidification and low salinity
Published 9 December 2022 Science ClosedTags: biological response, BRcommunity, crustaceans, growth, laboratory, mesocosms, mollusks, morphology, mortality, multiple factors, performance, predation, salinity
How ocean acidification (OA) interacts with other stressors is understudied, particularly for predators and prey. We assessed long-term exposure to decreased pH and low salinity on (1) juvenile blue crab Callinectes sapidus claw pinch force, (2) juvenile hard clam Mercenaria mercenaria survival, growth, and shell structure, and (3) blue crab and hard clam interactions in filmed mesocosm trials. In 2018 and 2019, we held crabs and clams from the Chesapeake Bay, USA, in crossed pH (low: 7.0, high: 8.0) and salinity (low: 15, high: 30) treatments for 11 and 10 wk, respectively. Afterwards, we assessed crab claw pinch force and clam survival, growth, shell structure, and ridge rugosity. Claw pinch force increased with size in both years but weakened in low pH. Clam growth was negative, indicative of shell dissolution, in low pH in both years compared to the control. Growth was also negative in the 2019 high-pH/low-salinity treatment. Clam survival in both years was lowest in the low-pH/low-salinity treatment and highest in the high-pH/high-salinity treatment. Shell damage and ridge rugosity (indicative of deterioration) were intensified under low pH and negatively correlated with clam survival. Overall, clams were more severely affected by both stressors than crabs. In the filmed predator-prey interactions, pH did not substantially alter crab behavior, but crabs spent more time eating and burying in high-salinity treatments and more time moving in low-salinity treatments. Given the complex effects of pH and salinity on blue crabs and hard clams, projections about climate change on predator-prey interactions will be difficult and must consider multiple stressors.
Continue reading ‘Biological responses of the predatory blue crab and its hard clam prey to ocean acidification and low salinity’Do pH-Variable habitats provide refuge for stone crabs from coastal acidification?
Published 2 December 2022 Science ClosedTags: biological response, crustaceans, education, field
PURPOSE OF ACTIVITY
This guided, inquiry-based, hands-on lesson uses data from a local monitoring station in Tampa Bay, Florida, to guide students toward understanding how coastal acidification may impact the reproductive success of the Florida stone crab, an important regional fishery. The objectives of the lesson are for students to: (1) determine how pH varies between different habitats, (2) determine how pH can affect the reproductive success of an important commercial fishery, the Florida stone crab, and (3) evaluate whether exposure to variable seawater pH results in greater reproductive success in stone crabs relative to individuals that are not exposed to pH variability.
AUDIENCE
This lesson is designed for undergraduates in introductory-level biology, marine biology, environmental chemistry, and oceanography courses. The activities introduce students to ocean acidification relationships associated with diel fluctuations in pH in benthic habitats like seagrass and sand. The lesson also correlates reductions in seawater pH to the reproductive success of a commercially important species, the Florida stone crab.
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Continue reading ‘Do pH-Variable habitats provide refuge for stone crabs from coastal acidification?’Transcriptome analysis of hepatopancreas in penaeus monodon under acute low pH stress
Published 1 December 2022 Science ClosedTags: biological response, crustaceans, fisheries, laboratory, mitigation, molecular biology, physiology
The decrease of seawater pH can affect the metabolism, acid-base balance, immune response and immunoprotease activity of aquatic animals, leading to aquatic animal stress, impairing the immune system of aquatic animals and weakening disease resistance, etc. In this study, we performed high-throughput sequencing analysis of the hepatopancreas transcriptome library of low pH stress penaeus monodon, and after sequencing quality control, a total of 43488612–56271828 Clean Reads were obtained, and GO annotation and KEGG pathway enrichment analysis were performed on the obtained Clean Reads, and a total of 395 DEGs were identified. we mined 10 differentially expressed and found that they were significantly enriched in the Metabolic pathways (ko01100), Biosynthesis of secondary metabolites (ko01110), Nitrogen metabolism (ko00910) pathways, such as PIGA, DGAT1, DGAT2, UBE2E on Metabolic pathways; UGT, GLT1, TIM genes on Biosynthesis of secondary metabolites; CA, CA2, CA4 genes on Nitrogen metabolism, are involved in lipid metabolism, induction of oxidative stress and inflammation in the muscular body of spot prawns. These genes play an important role in lipid metabolism, induction of oxidative stress and inflammatory response in the muscle of the shrimp. In summary, these genes provide valuable reference information for future breeding of low pH-tolerant shrimp.
Continue reading ‘Transcriptome analysis of hepatopancreas in penaeus monodon under acute low pH stress’Effects of hypoxia and acidification on Calanus pacificus: behavioral changes in response to stressful environments
Published 9 November 2022 Science ClosedTags: biological response, crustaceans, laboratory, mortality, multiple factors, oxygen, performance, zooplankton
Copepods, which play major roles in marine food webs and biogeochemical cycling, frequently undergo diel vertical migration (DVM), swimming downwards during the day to avoid visual predation and upwards at night to feed. Natural water columns that are stratified with chemical stressors at depth, such as hypoxia and acidification, are increasing with climate change. Understanding behavioral responses of copepods to these stresses—in particular, whether copepods alter their natural migration—is important to anticipating impacts of climate change on marine ecosystems. We conducted laboratory experiments using stratified water columns to measure the effects of bottom water hypoxia and pH on mortality, distribution, and swimming behaviors of the calanoid copepod Calanus pacificus. When exposed to hypoxic (0.65 mg O2 l-1) bottom waters, the height of C. pacificus from the bottom increased 20% within hypoxic columns, and swimming speed decreased 46% at the bottom of hypoxic columns and increased 12% above hypoxic waters. When exposed to low pH (7.48) bottom waters, swimming speeds decreased by 8 and 9% at the base of the tanks and above acidic waters, respectively. Additionally, we found a 118% increase in ‘moribund’ (immobile on the bottom) copepods when exposed to hypoxic, but not acidic, bottom waters. Some swimming statistics differed between copepods collected from sites with versus without historical hypoxia and acidity. Observed responses suggest potential mechanisms underlying in situ changes in copepod population distributions when exposed to chemical stressors at depth.
Continue reading ‘Effects of hypoxia and acidification on Calanus pacificus: behavioral changes in response to stressful environments’Do global environmental drivers’ ocean acidification and warming exacerbate the effects of oil pollution on the physiological energetics of Scylla serrata?
Published 8 November 2022 Science ClosedTags: biological response, crustaceans, Indian, laboratory, multiple factors, physiology, temperature, toxicants
Global climate change–induced ocean warming and acidification have complex reverberations on the physiological functioning of marine ectotherms. The Sundarbans estuarine system has been under threat for the past few decades due to natural and anthropogenic disturbances. In recent years, petroleum products’ transportation and their usage have increased manifold, which causes accidental oil spills. The mud crab (Scylla serrata) is one of the most commercially exploited species in the Sundarbans. The key objective of this study was to delineate whether rearing under global environmental drivers (ocean acidification and warming) exacerbates the effect of a local driver (oil pollution) on the physiological energetics of mud crab (Scylla serrata) from the Sundarbans estuarine system. Animals were reared separately for 30 days under (a) the current climatic scenario (pH 8.1, 28°C) and (b) the predicted climate change scenario (pH 7.7, 34°C). After rearing for 30 days, 50% of the animals from each treatment were exposed to 5 mg L−1 of marine diesel oil for the next 24 h. Physiological energetics (ingestion rate, absorption rate, respiration rate, excretion rate, and scope for growth), thermal performance, thermal critical maxima (CTmax), acclimation response ratio (ARR), Arrhenius activation energy (AAE), temperature coefficient (Q10), warming tolerance (WT), and thermal safety margin (TSM) were evaluated. Ingestion and absorption rates were significantly reduced, whereas respiration and ammonia excretion rates significantly increased in stressful treatments, resulting in a significantly lower scope for growth. A profound impact on thermal performance was also noticed, leading to a downward shift in CTmax value for stress-acclimated treatment. The present results clearly highlighted the detrimental combined effect of global climatic stressors and pollution on the physiological energetics of crabs that might potentially reduce their population and affect coastal aquaculture in forthcoming years.
Continue reading ‘Do global environmental drivers’ ocean acidification and warming exacerbate the effects of oil pollution on the physiological energetics of Scylla serrata?’Crustacean ecology in a changing climate
Published 4 November 2022 Science ClosedTags: biological response, crustaceans, mortality, multiple factors, oxygen, physiology, reproduction, review, salinity, temperature
Whilst crustaceans occupy a diversity of ecological niches and have adapted to many environmental challenges, relatively little is known on how the predicted changes associated with climate change will impact individuals, communities, species and ecosystems globally. Direct oceanic change to seawater temperature, pH, alkalinity, oxygen level and salinity and indirect impacts on weather, seasonality, food availability and changes in ecological networks will put pressure upon crustaceans to acclimate. There is now emerging evidence that behaviour, physiology, fitness and ultimately reproduction and survival of coastal crustaceans is altered under experimental climate change conditions, with most studies showing negative impacts. Nevertheless measurable endpoints, multigenerational and ecosystem studies are to date extremely rare and the full impact of climate change stress upon crustaceans is nowhere near fully understood.
Continue reading ‘Crustacean ecology in a changing climate’Crustacean decapods are models to describe the general trends of biodiversity according to ocean acidification
Published 3 November 2022 Science ClosedTags: communitymodeling, crustaceans, modeling, multiple factors, temperature
A remarkable lack of punctual and comparable data on the availability of trophic resources characterizes most studies relating biodiversity and food webs, but decapod crustaceans will help, in this study, finding some peculiar common trends of ecosystems. Structural properties of networks, as statistically investigated, affect their stability and food webs are ultimately considered as complex networks of biotic interactions. Fixed mathematical limits constrain the number of species naturally assembled in a community, even if species composition was progressively modified by climate changes: the biodiversity has space constraints. Consequently, since there is less space at higher latitudes than at lower ones, less species may be predicted to globally co-exist, as the planet warms up and the oceans acidify. Here, according to some key mathematical relationships of networks, we forecast an inverse relationship between connectance (a specific feature of food webs) and species diversity. In this chapter, we will apply these relationships to test a general model of biodiversity trends based on the responses of crustacean decapods to the abundance of feeding sources, in a range of environments variably impacted by O.A. The conclusions reached within this chapter will demonstrate consistent properties characterizing the assemblages of aquatic creatures, and extensible to various structural levels, from single cells to the largest ecosystems.
Continue reading ‘Crustacean decapods are models to describe the general trends of biodiversity according to ocean acidification’Ocean acidification does not overlook sex: review of understudied effects and implications of low pH on marine invertebrate sexual reproduction
Published 2 November 2022 Science ClosedTags: biological response, cnidaria, crustaceans, echinoderms, fisheries, mollusks, physiology, reproduction, review
Sexual reproduction is a fundamental process essential for species persistence, evolution, and diversity. However, unprecedented oceanographic shifts due to climate change can impact physiological processes, with important implications for sexual reproduction. Identifying bottlenecks and vulnerable stages in reproductive cycles will enable better prediction of the organism, population, community, and global-level consequences of ocean change. This article reviews how ocean acidification impacts sexual reproductive processes in marine invertebrates and highlights current research gaps. We focus on five economically and ecologically important taxonomic groups: cnidarians, crustaceans, echinoderms, molluscs and ascidians. We discuss the spatial and temporal variability of experimental designs, identify trends of performance in acidified conditions in the context of early reproductive traits (gametogenesis, fertilization, and reproductive resource allocation), and provide a quantitative meta-analysis of the published literature to assess the effects of low pH on fertilization rates across taxa. A total of 129 published studies investigated the effects of ocean acidification on 122 species in selected taxa. The impact of ocean acidification is dependent on taxa, the specific reproductive process examined, and study location. Our meta-analysis reveals that fertilization rate decreases as pH decreases, but effects are taxa-specific. Echinoderm fertilization appears more sensitive than molluscs to pH changes, and while data are limited, fertilization in cnidarians may be the most sensitive. Studies with echinoderms and bivalve molluscs are prevalent, while crustaceans and cephalopods are among the least studied species even though they constitute some of the largest fisheries worldwide. This lack of information has important implications for commercial aquaculture, wild fisheries, and conservation and restoration of wild populations. We recommend that studies expose organisms to different ocean acidification levels during the entire gametogenic cycle, and not only during the final stages before gametes or larvae are released. We argue for increased focus on fundamental reproductive processes and associated molecular mechanisms that may be vulnerable to shifts in ocean chemistry. Our recommendations for future research will allow for a better understanding of how reproduction in invertebrates will be affected in the context of a rapidly changing environment.
Continue reading ‘Ocean acidification does not overlook sex: review of understudied effects and implications of low pH on marine invertebrate sexual reproduction’Marine heatwave impacts on newly-hatched planktonic larvae of an estuarine crab
Published 25 October 2022 Science ClosedTags: biological response, crustaceans, laboratory, mortality, multiple factors, physiology, temperature, zooplankton
Highlights
- Larvae survival was affected by temperature increase regardless of pH conditions.
- Larvae heart beating and abdominal contractions were affected by temperature and pH.
- Over the past 38 years Santos/São Vicente coast had a mean SST increase of 0.85 °C.
- Higher intensity and duration of heatwaves are expected to reduce larval recruitment.
Abstract
Climate change is imposing constant and more severe environmental challenges to coastal and marine species. Regional climate and species acclimation capacity determine the communities’ ecological response to stressors. Marine heatwave events are of serious threat to species fitness and survivorship, even more to the sensitive early-history stages of ectotherms. By combining modeled regional historical data and climate change predictions with manipulative experiments, we evaluated the potential impact of marine heatwaves in a widespread and abundant planktonic larvae of the fiddler crab Leptuca thayeri. Larvae survival was affected by temperature increase with lowest survival probability under higher temperature treatments regardless of pH conditions. Larval physiology was affected by both temperature increase and pH conditions. With heatwaves becoming more frequent, hotter, and lasting longer in the region, we could expect potential reductions in the larval recruitment and stocks with cascade ecological negative effects on estuarine habitats.
Continue reading ‘Marine heatwave impacts on newly-hatched planktonic larvae of an estuarine crab’Interaction between reduced pH and multiple stressors affects the physiology of the fiddler crab Leptuca thayeri (Rathbun, 1900) (Decapoda: Brachyura: Ocypodidae)
Published 14 October 2022 Science ClosedTags: biological response, crustaceans, laboratory, mortality, multiple factors, physiology, salinity, temperature
Increasing ocean acidification combined with other impacts may cause changes in homeostatic mechanisms of intertidal invertebrates. Stressors do not act in isolation, and experimental work is needed to assess their synergistic potential. We evaluated the effect of exposure to multiple stressors on the survival, osmoregulation, metabolism, Q10, excretion, hepatosomatic index, and energy substrate oxidation on of the fiddler crab Leptuca thayeri (Rathbun, 1900). Crabs were exposed to two pH values (7.0, 6.3) combined with temperatures (20, 25, 30, 35, 40 °C) and these pH values combined with salinities (10, 20, 30, 40, and 50 psu) during acute exposure. All individuals died at 40 °C. Crabs osmoregulated, suggesting that the factors evaluated did not affect salt absorption or secretion. Individuals were weak hyperosmorregulators at lower salinities in the pH 7 control, but they became strong hyperosmoregulators at acidified pH 6.3. Alterations in oxygen consumption and hepatosomatic index were observed in individuals exposed to the acidified pH combined with temperatures or salinities, compared to those kept in the control pH. Q10 was elevated under an acidified pH, with crabs using proteins and lipids as energy substrates. The interaction between reduced pH and temperature or salinity thus affected physiological mechanisms related to the energetic metabolism, but elevated temperatures are more limiting because they affected survival. These physiological effects of acute exposure offer clues about extreme climatic events, which have a short duration but can affect the related energy demands.
Continue reading ‘Interaction between reduced pH and multiple stressors affects the physiology of the fiddler crab Leptuca thayeri (Rathbun, 1900) (Decapoda: Brachyura: Ocypodidae)’
