The Easter oyster, Crassostrea virginica, is an ecologically and economically important species native to the bays and estuaries all along the western Atlantic. However, it has declined to <10% of its pre-industrial numbers and faces further decline due to a combination of overharvesting, habitat destruction, climate change and disease. While efforts have been made to restore the population, a lack of knowledge about the oyster’s genetics and physiology presents an ongoing barrier to restoration. We turned to the microbiome present in the oyster’s extrapallial fluid (EPF) to learn more about this animal’s health and fitness, particularly in light of environmental stress including ocean acidification. Through a combination of marker gene and bacterial metatranscriptome sequencing, we found that the extrapallial fluid harbors a rich core bacterial community which is distinct from the surrounding water and plays potential roles in shell calcification and in pollutant bioremediation and nutrient (C, N, S) cycling both in the host and the environment. Using a limited panel of 36 single nucleotide polymorphisms (SNPs) we also found 7 host genetic markers which correlate with microbiome composition, suggesting that host genetics plays a role in shaping this community. This community is also resilient to low pH stress, suggesting that it is stable, self-sustaining, and able to carry out its role even during ocean acidification. Additional metagenomic studies and genome-wide association studies utilizing now-available C. virginica SNP microarrays may further elucidate this community’s role in host health and pave the way for future restoration-oriented interventions such as the development of probiotic treatments, microbial biomarkers to assess host health, and targeted breeding or genetic engineering guided by better knowledge of the relationship between host genotype and the Eastern oyster microbiome.
Continue reading ‘The microbiome of the eastern oyster, Crassostrea virginica, in health, disease and environmental stress’Posts Tagged 'mollusks'
The microbiome of the eastern oyster, Crassostrea virginica, in health, disease and environmental stress
Published 19 February 2024 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, North Atlantic, physiology
Reviews and syntheses: The clam before the storm – a meta-analysis showing the effect of combined climate change stressors on bivalves
Published 6 February 2024 Science ClosedTags: biological response, growth, mollusks, morphology, multiple factors, oxygen, review, salinity, temperature
The impacts of climate change on marine organisms have been increasingly documented in laboratory and experimental studies. However, the use of different taxonomic groupings and the assessment of a range of processes make identifying overall trends challenging. Meta-analysis has been used to determine general trends, but coarse taxonomic granularity may mask phylogenetically specific responses. Bivalve molluscs are a data-rich clade of ecologically and economically important calcifying marine taxa that allow for the assessment of species-specific vulnerability across developmental stages. Drawing on the large body of available literature, we conduct a meta-analysis of 203 unique experimental set-ups in order to examine how bivalve growth responds to increased water temperature, acidity, deoxygenation, and changes in salinity in 10 climate change stressor combinations. This is the most complete examination of bivalve responses to date and shows that anthropogenic climate change will disproportionally affect particular families, suggesting taxonomic differentiation in climate change response. Specifically, Mytilidae, Ostreidae, and Pectinidae (67 % of experiments) respond with negative effect sizes for all individual stressors, whereas responses in Pinnidae, Tellinidae, and Veneridae are more complex. Our analysis shows that earlier studies reporting negative impacts on bivalves are driven by only three or four well-studied, commercially important families. Despite the taxonomic differentiation, almost all drivers and their combinations have significant negative effects on growth. The synergistic impacts of deoxygenation, acidification, and temperature result in the largest negative effect size. Infaunal taxa, including Tellinidae and Veneridae, appear more resistant to warming and oxygen reduction than epifaunal or motile taxa, but this difference between the two taxa is also based on a small number of data points. The current focus of experimental set-ups on commercially important taxa and families within a small geographic range creates gaps in the understanding of global impacts on these economically important foundation organisms.
Continue reading ‘Reviews and syntheses: The clam before the storm – a meta-analysis showing the effect of combined climate change stressors on bivalves’Transcriptomics, proteomics, and physiological assays reveal immunosuppression in the eastern oyster Crassostrea virginica exposed to acidification stress
Published 30 January 2024 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, mortality, multiple factors, North Atlantic, pathogens, performance, physiology
Ocean acidification (OA) is recognized as a major stressor for a broad range of marine organisms, particularly shell-building invertebrates. OA can cause alterations in various physiological processes such as growth and metabolism, although its effect on host-pathogen interactions remains largely unexplored. In this study, we used transcriptomics, proteomics, and physiological assays to evaluate changes in immunity of the eastern oyster Crassostrea virginica exposed to OA conditions (pH = 7.5 vs pH = 7.9) at various life stages. The susceptibility of oyster larvae to Vibrio infection increased significantly (131 % increase in mortality) under OA conditions, and was associated with significant changes in their transcriptomes. The significantly higher mortality of larvae exposed to pathogens and acidification stress could be the outcome of an increased metabolic demand to cope with acidification stress (as seen by upregulation of metabolic genes) at the cost of immune function (downregulation of immune genes). While larvae were particularly vulnerable, juveniles appeared more robust to the stressors and there were no differences in mortality after pathogen (Aliiroseovarius crassostrea and Vibrio spp.) exposure. Proteomic investigations in adult oysters revealed that acidification stress resulted in a significant downregulation of mucosal immune proteins including those involved in pathogen recognition and microbe neutralization, suggesting weakened mucosal immunity. Hemocyte function in adults was also impaired by high pCO2, with a marked reduction in phagocytosis (67 % decrease in phagocytosis) in OA conditions. Together, results suggest that OA impairs immune function in the eastern oyster making them more susceptible to pathogen-induced mortality outbreaks. Understanding the effect of multiple stressors such as OA and disease is important for accurate predictions of how oysters will respond to future climate regimes.
Continue reading ‘Transcriptomics, proteomics, and physiological assays reveal immunosuppression in the eastern oyster Crassostrea virginica exposed to acidification stress’Examining the impacts of elevated, variable pCO2 on larval Pacific razor clams (Siliqua patula) in Alaska
Published 29 January 2024 Science ClosedTags: biological response, calcification, laboratory, molecular biology, mollusks, morphology, North Pacific, physiology
An increase in anthropogenic carbon dioxide is driving oceanic chemical shifts resulting in a long-term global decrease in ocean pH, colloquially termed ocean acidification (OA). Previous studies have demonstrated that OA can have negative physiological consequences for calcifying organisms, especially during early life-history stages. However, much of the previous research has focused on static exposure to future OA conditions, rather than variable exposure to elevated pCO2, which is more ecologically relevant for nearshore species. This study examines the effects of OA on embryonic and larval Pacific razor clams (Siliqua patula), a bivalve that produces a concretion during early shell development. Larvae were spawned and cultured over 28 days under three pCO2 treatments: a static high pCO2 of 867 μatm, a variable, diel pCO2 of 357 to 867 μatm, and an ambient pCO2 of 357 μatm. Our results indicate that the calcium carbonate polymorphism of the concretion phase of S. patula was amorphous calcium carbonate which transitioned to vaterite during the advanced D-veliger stage, with a final polymorphic shift to aragonite in adults, suggesting an increased vulnerability to dissolution under OA. However, exposure to elevated pCO2 appeared to accelerate the transition of larval S. patula from the concretion stage of shell development to complete calcification. There was no significant impact of OA exposure to elevated or variable pCO2 conditions on S. patula growth or HSP70 and calmodulin gene expression. This is the first experimental study examining the response of a concretion producing bivalve to future predicted OA conditions and has important implications for experimentation on larval mollusks and bivalve management.
Continue reading ‘Examining the impacts of elevated, variable pCO2 on larval Pacific razor clams (Siliqua patula) in Alaska’Early stage ecological communities on artificial algae showed no difference in diversity and abundance under ocean acidification
Published 24 January 2024 Science ClosedTags: abundance, algae, annelids, biological response, BRcommunity, calcification, chemistry, community composition, crustaceans, echinoderms, field, Mediterranean, mesocosms, mitigation, mollusks, otherprocess, photosynthesis, protists, respiration
Marine habitat-forming species create structurally complex habitats that host macroinvertebrate communities characterized by remarkable abundance and species richness. These habitat-forming species also play a fundamental role in creating favourable environmental conditions that promote biodiversity. The deployment of artificial structures is becoming a common practice to help offset habitat loss although with mixed results. This study investigated the suitability of artificial flexible turfs mimicking the articulated coralline algae (mimics) as habitat providers and the effect of ocean acidification (OA) on early stage ecological communities associated to flexible mimics and with the mature community associated to Ellisolandia elongata natural turfs. The mimics proved to be a suitable habitat for early stage communities. During the OA mesocosms experiment, the two substrates have been treated and analysed separately due to the difference between the two communities. For early stage ecological communities associated with the mimics, the lack of a biologically active substrate does not exacerbate the effect of OA. In fact, no significant differences were found between treatments in crustaceans, molluscs and polychaetes diversity and abundance associated with the mimics. In mature communities associated with natural turfs, buffering capability of E. elongata is supporting different taxonomic groups, except for molluscs, greatly susceptible to OA.
Continue reading ‘Early stage ecological communities on artificial algae showed no difference in diversity and abundance under ocean acidification’The molecular response of Mytilus coruscus mantle to shell damage under acute acidified sea water revealed by iTRAQ based quantitative proteomic analysis
Published 16 January 2024 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, North Pacific
Mytilus coruscus is an economically important marine bivalve that lives in estuarine sea areas with seasonal coastal acidification and frequently suffers shell injury in the natural environment. However, the molecular responses and biochemical properties of Mytilus under these conditions are not fully understood. In the present study, we employed tandem mass spectrometry combined with isobaric tagging to identify differentially expressed proteins in the mantle tissue of M. coruscus under different short-term treatments, including shell-complete mussels raised in normal seawater (pH 8.1), shell-damaged mussels raised in normal seawater (pH 8.1), and acidified seawater (pH 7.4). A total of 2694 proteins were identified in the mantle, and analysis of their relative abundance from the three different treatments revealed alterations in the proteins involved in immune regulation, oxidation-reduction processes, protein folding and processing, energy provision, and cytoskeleton. The results obtained by quantitative proteomic analysis of the mantle allowed us to delineate the molecular strategies adopted by M. coruscus in the shell repair process in acidified environments, including an increase in proteins involved in oxidation-reduction processes, protein processing, and cell growth at the expense of proteins involved in immune capacity and energy metabolism.
Continue reading ‘The molecular response of Mytilus coruscus mantle to shell damage under acute acidified sea water revealed by iTRAQ based quantitative proteomic analysis’Chapter 11: Effects of ocean warming and acidification on the soft-shell clam Mya arenaria
Published 12 January 2024 Science ClosedTags: biological response, BRcommunity, mollusks, review
Introduction
Since the onset of the Industrial Revolution and large-scale burning of fossil fuels, global climate change has driven rapid and unprecedented changes to our planet. The world’s oceans are no exception. Alongside the burning of fossil fuels, increasing human activity and development in coastal regions have further contributed to biological, physical, and chemical changes in coastal marine systems (Cloern et al. 2016). Given these widespread and rapid changes occurring in coastal oceans globally, marine global change has become an important issue of concern.
Two global change stressors of current concern in marine science are ocean acidification and warming. The oceans absorb a considerable amount (>90%) of excess heat trapped by greenhouse gases (Levitus et al. 2012). This heat absorption has resulted in large-scale ocean warming (Cheng et al. 2017; Yao et al. 2017), which is projected to continue into the future (Fox-Kemper et al. 2021). Oceans also serve as the planet’s largest carbon sink, absorbing approximately 25% to 30% of excess anthropogenic carbon dioxide from the atmosphere (Doney et al. 2009). Consequently, oceanic pH has dropped by approximately 0.1 pH units since the Industrial Revolution and is projected to drop another 0.44 units by the end of this century (based on latest Intergovernmental Panel on Climate Change projections under the SSP5-8.5 defined in their sixth assessment report; Canadell et al. 2021) in a process coined “ocean acidification” (Caldeira and Wickett 2003; Doney et al. 2009; Brewer 2013). Given the widespread and rapid change currently occurring in marine systems globally, understanding how acidification and warming might affect marine life has become a cornerstone of contemporary marine research.
Since soft-shell clams Mya arenaria are important to coastal regions both ecologically and economically (e.g., Seitz and Hines 2023; Beal 2023a, 2023b; Kennedy 2023, all this volume), it is critical to understand how this species may be affected by global change stressors such as acidification and warming. In this chapter, we review some of the potential independent and interactive effects of these stressors on soft-shell clams at the organismal, population, and community levels of biological organization. We draw on experimental studies conducted with M. arenaria, as well as other clam species with similar biological and/or ecological attributes, to synthesize the ways in which the stressors might affect soft-shell clams. We also discuss nuances of such effects on M. arenaria, including the mediating roles of environmental variability, habitat complexity, and acclimation and adaptation.
Continue reading ‘Chapter 11: Effects of ocean warming and acidification on the soft-shell clam Mya arenaria’Resilience against the impacts of climate change in an ecologically and economically significant native oyster
Published 22 December 2023 Science ClosedTags: biological response, laboratory, mollusks, multiple factors, performance, physiology, respiration, South Pacific, temperature
Highlights
- Climate change is acidifying and warming oceans.
- Building resilience of marine species will be essential to ensure their persistence.
- Resilience to climate change in oysters was identified in a large-scale experiment as the capacity to defend acid-base balance and have a positive Scope for Growth.
- Only 8 of 24 genetically distinct family lines of this economically and ecologically important oyster species had resilience.
Abstract
Climate change is acidifying and warming our oceans, at an unprecedented rate posing a challenge for marine invertebrates vital across the globe for ecological services and food security. Here we show it is possible for resilience to climate change in an ecologically and economically significant oyster without detrimental effects to the energy budget. We exposed 24 pair-mated genetically distinct families of the Sydney rock oyster, Saccostrea glomerata to ocean acidification and warming for 4w and measured their resilience. Resilience was identified as the capacity to defend their acid-base balance without a loss of energy available for Scope for Growth (SFG). Of the 24 families, 13 were better able to defend their acid-base balance while eight had no loss of energy availability with a positive SFG. This study has found oyster families with reslience against climate change without a loss of SFG, is an essential mitigation strategy, in a critical mollusc.
Continue reading ‘Resilience against the impacts of climate change in an ecologically and economically significant native oyster’Interactive effects of multiple antibiotic residues and ocean acidification on physiology and metabolome of the bay scallops Argopecten irradians irradians
Published 18 December 2023 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, morphology, multiple factors, North Pacific, performance, physiology, respiration, toxicants
Highlights
- Exposure to AM predominantly disrupted the purine metabolism pathway of A. irradians.
- Exposure to OA affected the energy metabolism and ammonia metabolism of A. irradians.
- The antagonistic effects of AM and OA exposure led to neurological disorders in A. irradians.
Abstract
Coastal areas are confronted with compounding threats arising from both climatic and non-climatic stressors. Antibiotic pollution and ocean acidification are two prevalently concurrent environmental stressors. Yet their interactive effects on marine biota have not been investigated adequately and the compound hazard remain obscure. In this study, bay scallops Argopecten irradians irradians were exposed to multiple antibiotics (sulfamethoxazole, tetracycline, oxytetracycline, norfloxacin, and erythromycin, each at a concentration of 1 μg/L) combined with/without acidic seawater (pH 7.6) for 35 days. The single and interactive effects of the two stressors on A. irradians irradians were determined from multidimensional bio-responses, including energetic physiological traits as well as the molecular underpinning (metabolome and expressions of key genes). Results showed that multiple antibiotics predominantly enhanced the process of DNA repair and replication via disturbing the purine metabolism pathway. This alternation is perhaps to cope with the DNA damage induced by oxidative stress. Ocean acidification mainly disrupted energy metabolism and ammonia metabolism of the scallops, as evidenced by the increased ammonia excretion rate, the decreased O:N ratio, and perturbations in amino acid metabolism pathways. Moreover, the antagonistic effects of multiple antibiotics and ocean acidification caused alternations in the relative abundance of neurotransmitter and gene expression of neurotransmitter receptors, which may lead to neurological disorders in scallops. Overall, the revealed alternations in physiological traits, metabolites and gene expressions provide insightful information for the health status of bivalves in a natural environmental condition under the climate change scenarios.
Continue reading ‘Interactive effects of multiple antibiotic residues and ocean acidification on physiology and metabolome of the bay scallops Argopecten irradians irradians’Spatiotemporal variation of China’s mariculture potential under climate change
Published 8 December 2023 Science ClosedTags: biological response, fish, fisheries, growth, modeling, mollusks, morphology, North Pacific, regionalmodeling
Being the world’s largest seafood producer, China’s mariculture is critical for ensuring national and global food security, yet greatly threatened by climate change. It is essential to assess the potential opportunities and challenges for Chinese mariculture in light of climate change. Although the impact of climate change on mariculture potential at a global scale has been investigated, studies at sub-national scales of China are scarce, particularly those that take into account multiple environmental stressors and species. Here, we applied a combination of physical and biological models to quantify the spatiotemporal variation in the mariculture potential of seven finfish species and seven bivalve species cultured in China under the emission scenarios SSP5-8.5 and SSP1-2.6 in the twentyfirst century. Our results demonstrated that the spatiotemporal trends in culture potential was species-specific. Finfish was less affected than bivalves. Four finfish species and seven bivalve species showed a continuously declining trend in culture potential and most species showed a northward shift of the centroid with high growth potential under SSP5-8.5. Under the scenario SSP1-2.6, the culture potential of finfish species mostly showed a stable or increasing trend, while that of bivalve species declined in the mid-twentyfirst century and partially recovered in the late twentyfirst century. Cold-water species exhibited a greater loss of culture potential than warm-water and eurythermal species. In the SSP5-8.5 and SSP1-2.6 scenarios, the cold-water species Oncorhynchus mykiss and Patinopecten yessoensis experienced the most significant loss in culture potential among finfish and bivalve species. Meanwhile, the culture potential for two out of the four warm-water species, specifically Epinephelus spp. and Sciaenops ocellatus, saw an increase. The culture potential for eight eurythermal species remained stable or declined. This study helps to identify mariculture potential for different species and sea areas and can inform the development of climate-resilient mariculture in China.
Continue reading ‘Spatiotemporal variation of China’s mariculture potential under climate change’Within- and transgenerational stress legacy effects of ocean acidification on red abalone (Haliotis rufescens) growth and survival
Published 4 December 2023 Science ClosedTags: adaptation, biological response, growth, laboratory, mollusks, mortality, otherprocess, reproduction
Understanding the mechanisms by which individual organisms respond and populations adapt to global climate change is a critical challenge. The role of plasticity and acclimation, within and across generations, may be essential given the pace of change. We investigated plasticity across generations and life stages in response to ocean acidification (OA), which poses a growing threat to both wild populations and the sustainable aquaculture of shellfish. Most studies of OA on shellfish focus on acute effects, and less is known regarding the longer term carryover effects that may manifest within or across generations. We assessed these longer term effects in red abalone (Haliotis rufescens) using a multi-generational split-brood experiment. We spawned adults raised in ambient conditions to create offspring that we then exposed to high pCO2 (1180 μatm; simulating OA) or low pCO2 (450 μatm; control or ambient conditions) during the first 3 months of life. We then allowed these animals to reach maturity in ambient common garden conditions for 4 years before returning the adults into high or low pCO2 treatments for 11 months and measuring growth and reproductive potential. Early-life exposure to OA in the F1 generation decreased adult growth rate even after 5 years especially when abalone were re-exposed to OA as adults. Adult but not early-life exposure to OA negatively impacted fecundity. We then exposed the F2 offspring to high or low pCO2 treatments for the first 3 months of life in a fully factorial, split-brood design. We found negative transgenerational effects of parental OA exposure on survival and growth of F2 offspring, in addition to significant direct effects of OA on F2 survival. These results show that the negative impacts of OA can last within and across generations, but that buffering against OA conditions at critical life-history windows can mitigate these effects.
Continue reading ‘Within- and transgenerational stress legacy effects of ocean acidification on red abalone (Haliotis rufescens) growth and survival’Assessing impacts of coastal warming, acidification, and deoxygenation on Pacific oyster (Crassostrea gigas) farming: a case study in the Hinase area, Okayama Prefecture, and Shizugawa Bay, Miyagi Prefecture, Japan (Update)
Published 24 November 2023 Science ClosedTags: biological response, chemistry, field, fisheries, modeling, mollusks, morphology, multiple factors, North Pacific, oxygen, regionalmodeling, reproduction, temperature
Coastal warming, acidification, and deoxygenation are progressing primarily due to the increase in anthropogenic CO2. Coastal acidification has been reported to have effects that are anticipated to become more severe as acidification progresses, including inhibiting the formation of shells of calcifying organisms such as shellfish, which include Pacific oysters (Crassostrea gigas), one of the most important aquaculture resources in Japan. Moreover, there is concern regarding the combined impacts of coastal warming, acidification, and deoxygenation on Pacific oysters. However, spatiotemporal variations in acidification and deoxygenation indicators such as pH, the aragonite saturation state (Ωarag), and dissolved oxygen have not been observed and projected in oceanic Pacific oyster farms in Japan. To assess the present impacts and project future impacts of coastal warming, acidification, and deoxygenation on Pacific oysters, we performed continuous in situ monitoring, numerical modeling, and microscopic examination of Pacific oyster larvae in the Hinase area of Okayama Prefecture and Shizugawa Bay in Miyagi Prefecture, Japan, both of which are famous for their Pacific oyster farms. Our monitoring results first found Ωarag values lower than the critical level of acidification for Pacific oyster larvae in Hinase, although no impact of acidification on larvae was identified by microscopic examination. Our modeling results suggest that Pacific oyster larvae are anticipated to be affected more seriously by the combined impacts of coastal warming and acidification, with lower pH and Ωarag values and a prolonged spawning period, which may shorten the oyster shipping period and lower the quality of oysters.
Continue reading ‘Assessing impacts of coastal warming, acidification, and deoxygenation on Pacific oyster (Crassostrea gigas) farming: a case study in the Hinase area, Okayama Prefecture, and Shizugawa Bay, Miyagi Prefecture, Japan (Update)’Changes in the macrobenthic infaunal community of the Southern California continental margin over five decades in relation to oceanographic factors
Published 23 November 2023 Science ClosedTags: abundance, biological response, BRcommunity, mollusks, North Pacific
Climate change has altered the physiochemical conditions of the coastal ocean but effects on infaunal communities have not been well assessed. Here, we used multivariate ordination to examine temporal patterns in benthic community composition from 4 southern California continental shelf monitoring programs that range in duration from 30 to 50 yr. Temporal changes were compared to variations in temperature, oxygen, and acidification using single-taxon random forest models. Species richness increased over time, coupled with a decline in overall abundance. Continental shelf macrobenthic communities from the 2010s comprised a broader array of feeding guilds and life history strategies than in the 1970s. Changing water temperature was associated with northward shifts in geographic distribution and increases in species abundance, while acidification was associated with southward shifts and declines in abundance of other species. Acidification was also associated with changes in depth distribution of benthic fauna, with shelled molluscs declining in abundance at depths most associated with increasing exposure to acidification. This broad-scale community-level analysis establishes causal hypotheses that set the stage for more targeted studies investigating shifts in abundance or distribution for taxa that appear to be responding to climate change-related disturbances.
Continue reading ‘Changes in the macrobenthic infaunal community of the Southern California continental margin over five decades in relation to oceanographic factors’Ocean acidification alters the transcriptomic response in the nervous system of Aplysia californica during reflex behaviour
Published 21 November 2023 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, performance, physiology
Ocean acidification (OA) has numerous impacts on marine organisms including behaviour. While behaviours are controlled in the neuro system, its complexity makes linking behavioural impairments to environmental change difficult. Here we use a neurological model Aplysia californica with well-studied simple neuro system and behaviours. By exposing Aplysia to current day (~500 micro atm) or near-future CO2 conditions (~1100 micro atm), we test the effect of OA on their tail withdrawal reflex (TWR) and the underlying neuromolecular response of the pleural-pedal ganglia, responsible for the behaviour. Under OA, Aplysia relax tails faster due to increased sensorin-A expression, an inhibitor of mechanosensory neurons. We further investigate how OA affects habituation, which produced a ‘sensitization-like’ behaviour and affected vesicle transport and stress response, revealing an influence of OA on neuronal and behavioural outputs associated with learning. Finally, we test whether GABA-mediated neurotransmission is involved in impaired TWR, but exposure to gabazine did not restore normal behaviour and provoked little molecular response, rejecting the involvement in TWR impairment. Instead, vesicular transport and cellular signalling link other neurotransmitter processes directly with TWR impairment. Our study shows effects of OA on neurological tissue parts that control for behaviour revealing the neurological mechanisms when faced with OA.
Continue reading ‘Ocean acidification alters the transcriptomic response in the nervous system of Aplysia californica during reflex behaviour’Global synthesis of the status and trends of ocean acidification impacts on shelled pteropods
Published 13 November 2023 Science ClosedTags: Antarctic, Arctic, biological response, chemistry, mollusks, morphology, North Pacific, physiology, zooplankton
The accumulation of anthropogenic CO₂ in the ocean has major ecological, socioeconomic, and biogeochemical impacts, with repercussions for the ocean as a critical carbon sink. Ocean acidification (OA) disproportionately affects marine calcifiers, among which pelagic zooplanktonic pteropods play a significant role in carbonate export. The pteropod, due to the susceptibility of its aragonite shell to rapid dissolution, is one of most vulnerable groups and a key indicator for OA regional monitoring, but its regional sensitivities have not yet been extrapolated over global scales. To delineate spatial and temporal changes in pteropod shell dissolution, global OA status and the OA rate of change were evaluated, based on gridded climatologies of observations and using a Regional Ocean Modeling System (ROMS) biogeochemical/ecosystem model. Pteropods, which dominate in the polar and subpolar regions, are characterized by low aragonite saturation state and low buffering capacity, where extended pteropod subsurface dissolution is projected. We show that pteropods are most susceptible to OA in the polar regions, subpolar North Pacific, and eastern boundary upwelling system regions, particularly the California and Humboldt Current Systems. Rates of acidification and corresponding increases in pteropod shell dissolution are projected to be the fastest in the North and South Equatorial Currents. These are the regions with the greatest impacts on pteropods and biogeochemical implications.
Continue reading ‘Global synthesis of the status and trends of ocean acidification impacts on shelled pteropods’Infestation of cultivated Pacific oysters by shell-boring polychaetes along the US West Coast: Prevalence is associated with season, culture method, and pH
Published 10 November 2023 Science ClosedTags: abundance, annelids, biological response, chemistry, community composition, field, molecular biology, mollusks, North Pacific, otherprocess, physiology
Shell-boring polychaetes have contributed to the collapse of several mariculture operations around the world. These pests burrow into the shells of bivalves, creating mud blisters that are unappealing to consumers and which make oysters less valuable on the half-shell market. The US Pacific region produces 38% of the farmed shellfish in the US, making it important to understand the prevalence and drivers of parasite infestation in this region. We sampled Pacific oysters (Crassostrea gigas; n = 4158) from 35 shellfish farms over four seasons (two winters and two summers) in four states (northern California (CA), Oregon (OR), Washington (WA), and Alaska (AK)) to document the prevalence of shell-boring polychaetes. We extracted worms from infested oysters and used mitochondrial (CO1, n = 139) and nuclear (18S rRNA, n = 224) markers to determine species identities. To identify the environmental correlates that were associated with infestation, we pooled environmental data from seven monitoring stations in Washington. We assessed whether seawater surface temperature (SST), salinity, and pH were associated with shell-boring polychaete infestation. Our sampling confirmed the presence of Polydora websteri in the study region, in addition to four other species of shell-boring polychaetes and seven unidentified haplotypes. The mean prevalences across all shell-boring polychaete species ranged from 23 to 45% across seasons between states. In general, prevalence was higher in the winter and among oysters cultured on the bottom versus in tumbled bags, but these results varied across states. We also found greater infestation by shell-boring polychaetes at less acidified sites (pH = 8–8.2). This work is the most comprehensive dataset to characterize shell-boring polychaetes along the US West Coast, providing an important baseline of prevalence, species distribution, and environmental associations.
Continue reading ‘Infestation of cultivated Pacific oysters by shell-boring polychaetes along the US West Coast: Prevalence is associated with season, culture method, and pH’Metabolic profiling of Mytilus coruscus mantle in response of shell repairing under acute acidification
Published 8 November 2023 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, North Pacific, physiology
Mytilus coruscus is an economically important marine bivalve mollusk found in the Yangtze River estuary, which experiences dramatic pH fluctuations due to seasonal freshwater input and suffer from shell fracture or injury in the natural environment. In this study, we used intact-shell and damaged-shell M. coruscus and performed metabolomic analysis, free amino acids analysis, calcium-positive staining, and intracellular calcium level tests in the mantle to investigate whether the mantle-specific metabolites can be induced by acute sea-water acidification and understand how the mantle responds to acute acidification during the shell repair process. We observed that both shell damage and acute acidification induced alterations in phospholipids, amino acids, nucleotides, organic acids, benzenoids, and their analogs and derivatives. Glycylproline, spicamycin, and 2-aminoheptanoic acid (2-AHA) are explicitly induced by shell damage. Betaine, aspartate, and oxidized glutathione are specifically induced by acute acidification. Our results show different metabolic patterns in the mussel mantle in response to different stressors, which can help elucidate the shell repair process under ocean acidification. furthermore, metabolic processes related to energy supply, cell function, signal transduction, and amino acid synthesis are disturbed by shell damage and/or acute acidification, indicating that both shell damage and acute acidification increased energy consumption, and disturb phospholipid synthesis, osmotic regulation, and redox balance. Free amino acid analysis and enzymatic activity assays partially confirmed our findings, highlighting the adaptation of M. coruscus to dramatic pH fluctuations in the Yangtze River estuary.
Continue reading ‘Metabolic profiling of Mytilus coruscus mantle in response of shell repairing under acute acidification’Linking physiological effects of environmental stressors from cellular to whole-organismal levels in the early-life history stages of Crassostrea virginica (eastern oyster)
Published 2 November 2023 Science ClosedTags: adaptation, biological response, laboratory, mollusks, morphology, mortality, North Atlantic, otherprocess, performance
The Eastern oyster, Crassostrea virginica (Gmelin, 1791), is an ecologically and economically important species that resides in dynamic coastal ecosystems along the East and Gulf coasts of the United States. The success of oyster populations depends on the recruitment of their early life stages, which are especially vulnerable to environmental stress due to high developmental energy demands. As climate change continues, it is necessary to anticipate how the early life stages of the Eastern oyster will respond to environmental stressors under ecologically relevant scenarios. Therefore, the goal of this dissertation was to understand how the early life stages of C. virginica are physiologically affected by multiple global climate change stressors from a holistic perspective by incorporating local environmental data, observations across three life stages (i.e., carryover effects), responses from two important types of Eastern oysters, and physiological metrics from the cellular to whole-organism levels. To achieve this goal, chapter two observes the relative importance of three environmental tolerance mechanisms (selective mortality, carryover effects, and phenotypic plasticity) in shaping the performance of juvenile oysters in response to salinity exposures during the larval stage. Findings from this chapter indicate that typical differences in salinity among successive larval cultures in shellfish hatcheries likely do not impact performance as juveniles; rather, phenotypic plasticity likely underpins juvenile oyster performance as their physiology correlated with environmental conditions during the juvenile phase, not the larval exposures. Chapter three investigates carryover effects in more detail to explore how multiple global climate change stressors, ocean acidification and ocean warming, might affect the physiology of larval C. virginica, if those effects carry over to impact the performance of juvenile oysters and lastly, if those carryover effects change under different future environmental scenarios. Conditions of ocean acidification and ocean warming did affect the larval stage of the Eastern oyster and carry over into the juvenile stage, though these effects were nuanced and context dependent. Specifically, carryover effects from conditions of acidification were more persistent and negative, whereas warming had more fleeting carryover, and cross-tolerant, effects that were generally positive. Continuing to observe the effects of ocean acidification and ocean warming on the Eastern oyster, chapter four compares the larval responses of wild and selectively bred oysters. C. virginica larvae from wild and selectively bred oysters responded differently to conditions of acidification, but not warming. Furthermore, wild oyster larvae may be more resilient in the face of ongoing climate change. Despite exhibiting more lethal and negative effects of acidified conditions early in the larval stage, wild oyster larvae compensated for these earlier negative effects, while larvae from selectively bred oysters began showing signs of stress towards the end of the experiment. Lastly, exploring the development of carryover effects, chapter five observes how conditions of acidification during the settlement stage (i.e., settlement and metamorphosis) carried over to impact the juvenile stage. No detectable carryover effects were found, even though conditions of acidification negatively affected tissue growth at the beginning of the settlement stage. Overall, while Eastern oysters are able to withstand environmental stress to some degree, there were sub-lethal and carryover effects from multiple global climate change stressors identified in this dissertation that could have consequences for both wild and selectively bred populations in the future. The results from this dissertation will support subsequent studies to accurately predict the future success of wild oyster populations (e.g., effects to recruitment) and aquaculture production based on their physiological performances in the face of ongoing climate change.
Continue reading ‘Linking physiological effects of environmental stressors from cellular to whole-organismal levels in the early-life history stages of Crassostrea virginica (eastern oyster)’Sex-specific responses of Ruditapes philippinarum to ocean acidification following gonadal maturation
Published 1 November 2023 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, North Pacific, physiology, reproduction
Ocean acidification (OA) can seriously affect marine bivalves at different levels of biological organization, generating widespread consequences on progeny recruitment and population maintenance. Yet, few effort has been devoted to elucidating whether female and male bivalves respond differentially to OA in their reproductive seasons. Here, we estimated differences in physiological responses of female and male Manila clams (Ruditapes philippinarum) to OA during gonadal maturation. In comparison to OA-stressed male clams, females significantly depressed activities in enzymes related to energy metabolism (NKA, T-ATP), antioxidant defence (SOD and MDA), and non-specific immune function (ACP), and downregulated expression of AMPK that plays a key role in cellular metabolism, indicating that sex did significantly affect responses of R. philippinarum to OA. Such sex-based differences can be likely couched in energetic terms, given the much more energetically expensive cost of egg production than that of sperms. These results indicate that sex-specific responses to OA during reproductive seasons do exist in marine bivalves, and therefore accounting for such sex specificity is of paramount importance when projecting population sustainability and formulating conservation strategies in an acidifying ocean.
Continue reading ‘Sex-specific responses of Ruditapes philippinarum to ocean acidification following gonadal maturation’Transcriptomic response of Mytilus coruscus mantle to acute sea water acidification and shell damage
Published 31 October 2023 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, morphology, North Pacific, physiology
Mytilus coruscus is an economically important marine calcifier living in the Yangtze River estuary sea area, where seasonal fluctuations in natural pH occur owing to freshwater input, resulting in a rapid reduction in seawater pH. In addition, Mytilus constantly suffers from shell fracture or injury in the natural environment, and the shell repair mechanisms in mussels have evolved to counteract shell injury. Therefore, we utilized shell-complete and shell-damaged Mytilus coruscus in this study and performed transcriptomic analysis of the mantle to investigate whether the expression of mantle-specific genes can be induced by acute seawater acidification and how the mantle responds to acute acidification during the shell repair process. We found that acute acidification induced more differentially expressed genes than shell damage in the mantle, and the biomineralization-related Gene Ontology terms and KEGG pathways were significantly enriched by these DEGs. Most DEGs were upregulated in enriched pathways, indicating the activation of biomineralization-related processes in the mussel mantle under acute acidification. The expression levels of some shell matrix proteins and antimicrobial peptides increased under acute acidification and/or shell damage, suggesting the molecular modulation of the mantle for the preparation and activation of the shell repairing and anti-infection under adverse environmental conditions. In addition, morphological and microstructural analyses were performed for the mantle edge and shell cross-section, and changes in the mantle secretory capacity and shell inner film system induced by the two stressors were observed. Our findings highlight the adaptation of M. coruscus in estuarine areas with dramatic fluctuations in pH and may prove instrumental in its ability to survive ocean acidification.
Continue reading ‘Transcriptomic response of Mytilus coruscus mantle to acute sea water acidification and shell damage’
