Ocean warming and acidification are among the biggest threats to the persistence of coral reefs. Organismal stress tolerance thresholds are life stage specific, can vary across levels of biological organization, and also depend on natural environmental variability. Here, we exposed the early life stages of Pocillopora acuta in Kāne‘ohe Bay, Hawai‘i, USA, a common reef-building coral throughout the Pacific, to projected ocean warming and acidification scenarios. We measured ecological, physiological, biomineralization, and molecular responses across the critical transition from larvae to newly settled recruits following 6 days of exposure to diel fluctuations in temperature and pH in Control (26.8-27.9°C, 7.82-7.96 pHTotal), Mid (28.4-29.5°C, 7.65-7.79 pHTotal) and High conditions (30.2-31.5°C, 7.44-7.59 pHTotal). We found that P. acuta early life stages are capable of survival, settlement, and calcification under all scenarios. The High conditions, however, caused a significant reduction in survival and settlement capacity, with changes in the skeletal fiber deposition patterns. In contrast to a limited impact on the expression of biomineralization genes, the dominant transcriptomic response to the High conditions relative to the two other treatments included depressed metabolism, reduced ATP production and increased activity of DNA damage-repair processes. Collectively, our findings indicate that corals living in environments with large diurnal fluctuations in seawater temperature and pH, such as Kāne‘ohe Bay, can tolerate exposure to moderate projected increased temperature and reduced pH. However, under more severe environmental conditions significant negative effects on coral cellular metabolism and overall organismal survival jeopardize species fitness and recruitment.
Continue reading ‘Exposure to a gradient of warming and acidification highlights physiological,molecular, and skeletal tolerance thresholds in Pocillopora acuta recruits’Posts Tagged 'reproduction'
Exposure to a gradient of warming and acidification highlights physiological,molecular, and skeletal tolerance thresholds in Pocillopora acuta recruits
Published 21 January 2025 Science ClosedTags: biological response, corals, laboratory, molecular biology, morphology, mortality, multiple factors, North Pacific, reproduction, temperature
Meta-analysis of larval bivalve growth in response to ocean acidification and its application to sea scallop larval dispersal in the Mid-Atlantic Bight
Published 21 January 2025 Science ClosedTags: biological response, growth, individualmodeling, modeling, mollusks, reproduction, review
Ocean acidification, caused by increasing atmospheric carbon dioxide and coastal physical, biological, and chemical processes, is an ongoing threat to carbonate-utilizing organisms living in productive coastal shelves. Bivalves exposed to acidification have shown reduced growth, reproduction, and metabolic processes, with larval stages exhibiting the greatest susceptibility. Here, we compile results from published studies on larval bivalve growth responses to acidification to estimate a relationship between larval growth and seawater aragonite saturation state. We then apply this relationship to a larval dispersal individual-based model for Atlantic sea scallops (Placopecten magellanicus), an economically vital species in the Mid-Atlantic Bight that is historically under-studied in acidification research. To date, there have been no published studies on sea scallop larval response to ocean acidification. Model simulations allowed the identification of potential impacts of acidification on scallop success in the region. Results show that larval sea scallops that are sensitive to ocean acidification had a 17% lower settlement success rate and over 50% reduction in larval passage between major Mid Atlantic Bight fisheries habitats than those that are not sensitive to acidification. Additionally, temperature and ocean acidification interact as drivers of larval success, with aragonite saturation states > 3.0 compensating for temperature-induced mortality (> 19 ˚C) in some cases. This balance between drivers influences larval settlement success across spatial and interannual scales in the Mid Atlantic Bight.
Continue reading ‘Meta-analysis of larval bivalve growth in response to ocean acidification and its application to sea scallop larval dispersal in the Mid-Atlantic Bight’Effects of sediment acidification on germinability of Scrippsiella acuminata cysts in hypoxic zones
Published 16 January 2025 Science ClosedTags: biological response, field, laboratory, morphology, North Pacific, phytoplankton, reproduction, sediment
We investigated the calcareous cysts of Scrippsiella acuminata, with a focus on morphological changes from spiny to naked types in the surface sediments of hypoxic zones. The cyst-type abundance and bottom environmental conditions at two stations, representing hypoxic and normoxic conditions, were compared. Germination tests simulating in situ pH conditions were conducted to elucidate differences in germinability between spiny and naked cysts. The pH values at the hypoxic station reached a minimum of 7.2 in September, coinciding with high bottom-water temperatures and low dissolved oxygen levels. Significant differences in cyst abundance were observed; naked and intermediate cysts dominated the hypoxic station, whereas spiny cysts were more abundant at the normoxic station. Both cyst types exhibited a similar negative effect of germinability decrease (62 to 25% for spiny cysts and 75 to 32% for naked cysts) in acidic conditions (7.2) compared to normal pH conditions (7.7). Morphological changes in ungerminated cysts, such as cytoplasmic degradation and wall thickening, occurred under acidified conditions.
Continue reading ‘Effects of sediment acidification on germinability of Scrippsiella acuminata cysts in hypoxic zones’Molecular response to CO2-driven ocean acidification in the larvae of the sea urchin Hemicentrotus pulcherrimus: evidence from comparative transcriptome analyses
Published 13 January 2025 Science ClosedTags: biological response, echinoderms, laboratory, molecular biology, morphology, North Pacific, reproduction
Highlights
- Ocean acidification affects morphology of Hemicentrotus pulcherrimus larvae.
- Comparative transcriptome analyses were performed.
- Six key potential biomarkers correlated with low pH tolerance were identified.
Abstract
In order to explore the impact of CO2-driven ocean acidification (OA) on gene expression of sea urchins, gametes of Hemicentrotus pulcherrimus were fertilized and developed to the four-armed larvae in either seawater at current pH levels (pHNBS = 7.98) or in three laboratory-controlled OA conditions (ΔpHNBS = −0.3, −0.4, −0.5 units) based on the projections of the Intergovernmental Panel on Climate Change (IPCC) for 2100. Four-armed larval specimens were collected, and comparative transcriptome analysis was then performed. The results showed that 58 differentially expressed genes (DEGs) were identified in OA-treated groups as compared to the control. Moreover, more transition and transversion SNPs were observed in OA-treated groups than those in the control indicating a potential occurrence of adaption to OA in H. pulcherrimus larvae. Six candidate DEGs shared among OA-treated groups were identified as potential biomarkers correlated with low pH tolerance, mainly enriched in nine pathways associated with Notch signaling, dorso-ventral axis formation, oxidative phosphorylation, lysine degradation, valine, leucine and isoleucine degradation, lysosome, cell adhesion molecules, glutathione metabolism and PPAR signaling pathway. These results will not only enrich our knowledge of the impacts of OA on sea urchin larvae from the aspect of gene expression, provide a better understanding on larval forms coping with OA, but also offer more clues and biomarkers for developing protection or management strategies for sea urchins under near-future OA conditions.
Continue reading ‘Molecular response to CO2-driven ocean acidification in the larvae of the sea urchin Hemicentrotus pulcherrimus: evidence from comparative transcriptome analyses’Dynamic responses during early development of the sea urchin Strongylocentrotus intermedius to CO2-driven ocean acidification: a microRNA-mRNA integrated analysis
Published 9 January 2025 Science ClosedTags: biological response, echinoderms, laboratory, molecular biology, reproduction
Highlights
- Sea urchin blastula stage is the most sensitive stage to ocean acidification (OA).
- The PI3K/Akt pathway may be a hub pathway responding to OA in sea urchin larvae.
- MiR-1 may be a key regulator in the dynamic response of sea urchin larvae to OA.
Abstract
To explore the dynamic molecular responses to CO2-driven ocean acidification (OA) during the early developmental stages of sea urchins, gametes of Strongylocentrotus intermedius were fertilized and developed to the four-armed larva stage in either natural seawater (as a control; pHNBS = 7.99 ± 0.01) or acidified conditions (ΔpHNBS = −0.3, −0.4, and − 0.5 units) according to the prediction for ocean pH by the end of this century. Specimens from five developmental stages (fertilization, cleavage, blastula, prism, and four-armed larva) were collected and comparative microRNA (miRNA) and mRNA transcriptome analyses were performed. The results showed that 1) a total of 22,224 differentially expressed genes (DEGs) and 51 differentially expressed miRNAs (DEMs) were identified in the OA-treated groups compared with the control group. 2) The numbers of both DEGs and DEMs were the largest at the blastula stage, indicating dramatic changes in gene expression. 3) Five “miR-1/DEG” modules were identified as potential biomarkers reflecting the response of sea urchins to OA during the early developmental period. 4) The PI3K/Akt signaling pathway was a key pathway involved in the response of S. intermedius to OA in its early developmental stages. This study deepens our understanding of the dynamic molecular regulatory mechanisms underlying sea urchin responses to CO2-driven OA.
Continue reading ‘Dynamic responses during early development of the sea urchin Strongylocentrotus intermedius to CO2-driven ocean acidification: a microRNA-mRNA integrated analysis’Low pH means more female offspring: a multigenerational plasticity in the sex ratio of marine bivalves
Published 7 January 2025 Science ClosedTags: biological response, field, laboratory, molecular biology, mollusks, North Pacific, reproduction
Global changes can profoundly affect the sex determination and reproductive output of marine organisms, disrupting the population structure and ecosystems. High CO2-driven low pH in the context of ocean acidification (OA) has been shown to severely affect various calcifiers, but less is known about the extent to which low pH influences sex determination and reproduction of marine organisms, particularly mollusks. This study is the first to report a biased sex ratio over multiple generations toward females, driven by exposure to high CO2-induced low pH environments, using the ecologically and economically important Portuguese oyster (Crassostrea angulata) as a model. This phenomenon, which we term pH-mediated sex determination (PSD), has no consequences for fecundity, gonadal development, or reproductive function in the offspring. Moreover, PSD persisted into a second year of reproduction and was inherited across multiple generations. Transcriptomic analysis indicates PSD is associated with the activation of the Wnt signaling pathway in females and inhibition of spermiogenesis-related functions in males. This work expands our understanding of environmental sex determination and highlights the possible impact of global changes on reproduction and population dynamics of mollusks and other marine organisms.
Continue reading ‘Low pH means more female offspring: a multigenerational plasticity in the sex ratio of marine bivalves’Characterization of coral communities in the shallow hydrothermal vents of Mabini, Batangas, Philippines
Published 31 December 2024 Science ClosedTags: algae, biological response, BRcommunity, chemistry, community composition, corals, field, growth, North Pacific, reproduction, vents
The existence of shallow hydrothermal vents in Mabini, Batangas, Philippines, has been recognized to contribute to CO2-rich submarine groundwater discharges. However, little is known about the existing coral community structure in the area which provides valuable ecosystem goods and ecological services. We characterized the reef community in this unique microenvironment falls within the predicted future reef condition with low pH and aragonite saturation using coral recruitment tiles, examined coral life-history strategies and size frequency distribution, and measured calcification of transplanted fragments from the genus Goniopora sp., Pectinia sp., and Porites sp. The availability of larval supply has proven that corals can still settle (45–73 recruits m−2) due to the presence of hard substrate and settlement cues such as the crustose coralline algae. The existing coral colonies were mostly dominated by stress-tolerant groups and sizes ranging from 5 to 20 cm. Deployed coral fragments showed growth via extension, and calcification was negatively affected by local conditions, such as Porites sp. fragments. Higher nutrient input may have promoted coral growth, but combined with low carbonate chemistry, it likely made the corals more susceptible to physical damage, as seen on the fragments. This study highlights the importance of naturally occurring extreme environments to determine climate-resilient corals that can adapt to changing conditions and recover from disturbances over time.
Continue reading ‘Characterization of coral communities in the shallow hydrothermal vents of Mabini, Batangas, Philippines’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’Effects of ocean acidification on abalone (Haliotis spp.) reproduction, early development, and growth: a review
Published 5 December 2024 Science ClosedTags: biological response, calcification, mollusks, morphology, mortality, physiology, reproduction, review, socio-economy
Abalone (Haliotis spp.) is a highly valuable and economically relevant marine commodity worldwide, with its production and value showing significant growth over the past two decades. Additionally, abalone hold essential ecological value by serving as a grazer and providing a microhabitat for various benthic organisms. Currently, seawater is experiencing a decrease in pH due to increased carbon dioxide (CO2) levels. It is projected that by 2100, the pH of seawater will decrease by approximately 0.3–0.4 units, with this trend continuing to 0.7–0.8 units by 2300. Abalone is particularly susceptible to ocean acidification due to its limited ability to maintain acid-base balance. Moreover, even if the effects on abalone are not lethal, world production values and ecosystem balance are likely to be impacted. This review examines the economic and ecological significance of abalone, as well as the morphological and physiological effects of ocean acidification on abalone during its early development, juvenile, and adult stages based on previous studies. In summary, the adverse effects of ocean acidification on abalone depend on several aspects, including the species, developmental stage, size, and duration of exposure.
Continue reading ‘Effects of ocean acidification on abalone (Haliotis spp.) reproduction, early development, and growth: a review’Varying effects of climate change on the photosynthesis and calcification of crustose coralline algae: implications for settlement of coral larvae
Published 4 December 2024 Science ClosedTags: algae, biological response, BRcommunity, calcification, corals, laboratory, molecular biology, multiple factors, photosynthesis, physiology, reproduction, temperature
Highlights
- Corals maintain settlement preferences under future climate conditions
- Future climate conditions negatively affect crustose coralline algae physiology
- Physiological responses to future climate conditions varied by algal species
Abstract
Coral recruitment is critical to the maintenance of healthy coral reef ecosystems. Many coral species settle preferentially on certain crustose coralline algae (CCA) (e.g., Hydrolithon boergesenii) over others (e.g., Paragoniolithon solubile). Calcifying organisms like CCA are particularly susceptible to ocean acidification (OA), and settlement behavior of larvae may be compromised as seawater temperatures increase (ocean warming; OW) and pH levels decrease as a result of climate change. Here, we examine the effects of future seawater conditions (OW and OA) on the calcification and photosynthetic efficiency of two CCA species, H. boergesenii and Pa. solubile. We also examine the effects of conditioning CCA in combined OA and OW on the settlement preferences of three coral species, Acropora palmata, A. cervicornis and Porites astreoides. Acropora palmata and Po. astreoides demonstrated a preference for H. boergesenii over Pa. solubile in choice experiments after short-term treatment (7–21 days) and this preference was not affected by future seawater conditions. A. cervicornis did not demonstrate a CCA preference under any treatment. Po. astreoides did not demonstrate a CCA preference in no-choice assays and settlement was unaffected by OW and OA even after the longest exposure (99 days). Both CCA had reduced photosynthetic efficiency after exposure to future seawater conditions. However, net calcification rate was reduced in H. boergesenii but not Pa. solubile after exposure to future seawater conditions. These results demonstrate that while climate change may differentially affect the physiological functioning of various species of CCA, coral settlement preferences are unlikely to be altered.
Continue reading ‘Varying effects of climate change on the photosynthesis and calcification of crustose coralline algae: implications for settlement of coral larvae’Performance of Acanthina monodon juveniles under long-term exposure to predicted climate change conditions
Published 27 November 2024 Science ClosedTags: biological response, BRcommunity, laboratory, mollusks, morphology, mortality, multiple factors, physiology, reproduction, temperature
Highlights
- Combination of increasing temperature and decreasing pH increased juvenile shell growth.
- Decrease in pH has a negative effect on shell strength.
- Juveniles exposed to the higher temperature attached strongly to substrate.
- Under prolonged exposure, juveniles appear to compensate for high temperature/low pH stress.
- PCO2/temperature interaction had no effect on metabolic rate or juvenile survival.
Abstract
The increase of anthropogenic CO2 in the Earth’s atmosphere reduces the pH and raises the temperature of the oceans. The combination of both factors impacts the physiological responses and calcium carbonate structures of marine organisms. This study assessed the performance of the juvenile stage of the gastropod Acanthina monodon, after it was continuously exposed to treatments at two pCO2 levels (400 and 1200 μatm) at two temperatures (10 °C and 15 °C) during the periods of embryonic encapsulated development and the early post-hatching juvenile stage. Juvenile performance was evaluated by quantifying shell growth, survival, foot adhesion strength, shell breakage resistance, and oxygen consumption rates. The results indicate that the combination of increased temperature and decreased pH increased juvenile shell growth, while only the decrease in pH had a negative effect on shell strength. However, juveniles were able to attach more strongly to substrates following exposure to the higher temperature level. Furthermore, the interaction of treatments had no effect on the metabolic rate or survival of juveniles, suggesting a possible compensatory effect of the juveniles to the more adverse conditions to which they were exposed.
Continue reading ‘Performance of Acanthina monodon juveniles under long-term exposure to predicted climate change conditions’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’Chemical interactions between kelp Macrocystis pyrifera and symbiotic bacteria under elevated CO2 condition
Published 26 November 2024 Science ClosedTags: algae, biological response, community composition, molecular biology, otherprocess, physiology, prokaryotes, protists, reproduction
Kelps are pivotal to temperate coastal ecosystems, providing essential habitat and nutrients for diverse marine life, and significantly enhancing local biodiversity. The impacts of elevated CO2 levels on kelps may induce far-reaching effects throughout the marine food web, with potential consequences for biodiversity and ecosystem functions. This study considers the kelp Macrocystis pyrifera and its symbiotic microorganisms as a holistic functional unit (holobiont) to examine their collective response to heightened CO2 levels. Over a 4 month cultivation from the fertilization of M. pyrifera gametes to the development of juvenile sporophytes, our findings reveal that elevated CO2 levels influence the structure of the M. pyrifera symbiotic microbiome, alter metabolic profiles, and reshape microbe-metabolite interactions using 16S rRNA amplicon sequencing and liquid chromatography coupled to mass spectrometry analysis. Notably, Dinoroseobacter, Sulfitobacter, Methylotenera, Hyphomonas, Milano-WF1B-44 and Methylophaga were selected as microbiome biomarkers, which showed significant increases in comparative abundance with elevated CO2 levels. Stress-response molecules including fatty-acid metabolites, oxylipins, and hormone-like compounds such as methyl jasmonate and prostaglandin F2a emerged as critical metabolomic indicators. We propose that elevated CO2 puts certain stress on the M. pyrifera holobiont, prompting the release of these stress-response molecules. Moreover, these molecules may aid the kelp’s adaptation by modulating the microbial community structure, particularly influencing potential pathogenic bacteria, to cope with environmental change. These results will enrich the baseline data related to the chemical interactions between the microbiota and M. pyrifera and provide clues for predicting the resilience of kelps to future climate change.
Continue reading ‘Chemical interactions between kelp Macrocystis pyrifera and symbiotic bacteria under elevated CO2 condition’Symbiodiniaceae algal symbionts of Pocillopora damicornis larvae provide more carbon to their coral host under elevated levels of acidification and temperature
Published 25 November 2024 Science ClosedTags: biological response, BRcommunity, corals, laboratory, molecular biology, mortality, multiple factors, North Pacific, photosynthesis, physiology, primary production, protists, reproduction, respiration, temperature
Climate change destabilizes the symbiosis between corals and Symbiodiniaceae. The effects of ocean acidification and warming on critical aspects of coral survical such as symbiotic interactions (i.e., carbon and nitrogen assimilation and exchange) during the planula larval stage remain understudied. By combining physiological and stable isotope techniques, here we show that photosynthesis and carbon and nitrogen assimilation (H13CO3− and 15NH4+) in Pocillopora damicornis coral larvae is enhanced under acidification (1000 µatm) and elevated temperature (32 °C). Larvae maintain high survival and settlement rates under these treatment conditions with no observed decline in symbiont densities or signs of bleaching. Acidification and elevated temperature both enhance the net and gross photosynthesis of Symbiodiniaceae. This enhances light respiration and elevates C:N ratios within the holobiont. The increased carbon availability is primarily reflected in the 13C enrichment of the host, indicating a greater contribution of the algal symbionts to the host metabolism. We propose that this enhanced mutualistic symbiotic nutrient cycling may bolster coral larvae’s resistance to future ocean conditions. This research broadens our understanding of the early life stages of corals by emphasizing the significance of symbiotic interactions beyond those of adult corals.
Continue reading ‘Symbiodiniaceae algal symbionts of Pocillopora damicornis larvae provide more carbon to their coral host under elevated levels of acidification and temperature’Cross-talk between tissues is critical for intergenerational acclimation to environmental change in Acanthochromis polyacanthus
Published 21 November 2024 Science ClosedTags: adaptation, biological response, fish, laboratory, molecular biology, otherprocess, performance, physiology, reproduction
Organisms’ responses to environmental changes involve complex, coordinated responses of multiple tissues and potential parental influences. Here using a multi-tissue approach we determine how variation in parental behavioural tolerance and exposure to elevated CO2 influences the developmental and intergenerational molecular responses of their offspring in the coral reef fish Acanthochromis polyacanthus to future ocean acidification (OA) conditions. Gills and liver showed the highest transcriptional response to OA in juvenile fish regardless of parental OA conditioning, while the brain and liver showed the greatest intergenerational acclimation signals. Developmentally induced signals of OA, such as altered neural function in the brain, were restored to control levels after intergenerational exposure. Intergenerational CO2 exposure also enabled the offspring to adjust their metabolic processes, potentially allowing them to better meet the energetic demands of a high CO2 environment. Furthermore, offspring of OA-exposed parents differentially expressed a new complement of genes, which may facilitate intergenerational acclimatory responses. A genetic component of intergenerational plasticity also played a crucial role, with the parental behavioural phenotype largely determining the offspring’s transcriptional signals. Overall, our results reveal tissue-specific transcriptional changes underlying intergenerational plastic responses to elevated CO2 exposure, enhancing understanding of organismal acclimation to OA throughout the whole body.
Continue reading ‘Cross-talk between tissues is critical for intergenerational acclimation to environmental change in Acanthochromis polyacanthus’Drivers of biological diversity and responses to global changes in marine invertebrates
Published 12 November 2024 Science ClosedTags: adaptation, biological response, BRcommunity, community composition, corals, echinoderms, Indian, laboratory, molecular biology, otherprocess, reproduction
Human activities, in particular global changes (e.g., ocean warming – OW and ocean acidification – OA) are projected to drive some marine species to extinction within the coming decades. Marine invertebrates are amongst the most vulnerable to these changes due to the increased energetic cost to maintain intracellular pH homeostasis. To mitigate extinction, organisms may migrate, acclimate or adapt genetically. While these mechanisms are increasingly documented, they are not fully understood. This knowledge is critical for assessment of extinction risks, an important index for effective conservation and management of marine biodiversity. This thesis aims to increase our understanding on the drivers of biological diversity and sensitivity of marine invertebrates to OW and OA. Specifically, I assess (1) the quality of inferences on adaptive evolution in recent publications on responses of marine invertebrates to OW or OA and summarize the current knowledge and identify the gaps (Paper I); (2) the drivers of genetic diversity, structure, connectivity among Acropora austera populations across Mozambique coral reefs (Paper II); (3) the sensitivity to low pH in larvae of the sea urchin, Tripneustes gratilla, from subtidal and intertidal seagrass meadows with contrasting pH variability at Inhaca Island, Mozambique (Paper III); (4) the role of natural fluctuation in pH on the response of larvae of the sea urchin Echinus esculentus to low pH (Paper IV). Field genome scans surveys, laboratory experiments and systematic literature review were used. My systematic literature review (Paper I) highlights that publication on adaptive responses of marine invertebrates to OW or OA used more frequently strong methods for inferences of genetic change, such as common garden experiments and molecular genetic analysis. Methods for weaker inferences, such as comparison to model prediction, were less frequently used. On the other hand, reciprocal transplants, the stronger method for inferring adaptive change was less used in comparison with weaker methods such as phenotypic and genotypic selection. I also showed different levels of genetic variability and connectivity between populations of corals along the Mozambique coast. These geographic differences in levels of genetic diversity and connectivity may be explained by oceanographic factors and mode of reproduction of the corals (Paper II). Larvae of the sea urchin T. gratilla from Inhaca Island had reduced fitness when exposed to low pH. Moreover, larvae from adults collected in an intertidal habitat were more sensitive to low pH as compared to larvae from adults collected in a subtidal population. This result reveals population specific responses to low pH and challenges current theories that predict higher tolerance in individuals living in habitats with higher pH range (Paper III). Under present day natural variability in pH, the extreme low pH does not appear to be the main driver of biological responses in larvae of the sea urchin E. esculentus and adaptation to such conditions might be associated with a cost of plasticity but not a cost of canalization (Paper IV). Overall, this thesis shows that oceanographic factors and natural variability in pH influence the levels of genetic diversity and biological sensitivity in populations of marine invertebrates. These parameters should be considered to better evaluate the ability of marine invertebrates to withstand environmental changes and to sustain the provision of ecological functions, and guide conservation strategies.
Continue reading ‘Drivers of biological diversity and responses to global changes in marine invertebrates’Impacts of UV-filter pollution and low pH: sperm and adult biomarkers in the mussel Mytilus galloprovincialis in a multi-stressor context
Published 7 November 2024 Science ClosedTags: biological response, laboratory, Mediterranean, mollusks, multiple factors, North Atlantic, physiology, reproduction, toxicants
Highlights
- Low pH emerged as a main driver of responses, amplifying UV-filters’ effects on both biological levels.
- Sperm quality was relatively unaffected by UV-filters but significantly impacted by pH 7.7.
- Exposure to low pH resulted in redox imbalance and reduced lipid peroxidation levels in sperm cells.
- UV-filters, alone or combined with low pH, increased adults’ metabolic activity and energy storage.
- Activation of antioxidant and biotransformation defense systems, with increased ACP activity across all treatments.
Abstract
In an era of unprecedented environmental changes, understanding the combined effects of multiple stressors on species’ performance is urgent. The increasing UV-filter incorporation in daily-life products raises concerns about their potential impact on marine-coastal environments upon release. As stressors rarely act alone, global change-induced factors, such as ocean acidification (OA), can amplify ecological hazards promoted by contaminants in coastal realms. This study investigated the combined impacts of UV-filters 4-methylbenzylidene camphor (4-MBC) and benzophenone-3 (BP-3), at ecologically relevant concentrations (1 and 10 µg/L), under two target pH levels (8.2 and 7.7, reflecting a ∆pH of 0 and -0.3 relative to the average pH at the sampling site), on the biochemical performance and male reproductive health of the mussel Mytilus galloprovincialis. Using sperm and adult assays alongside a multi-biomarker approach, the study revealed that pH was the primary driver of the decline in mussel physiological and biochemical performances, further intensifying UV-filters’ impacts. While sperm cells showed adaptive responses to low pH conditions alone, characterized by reduced lipid peroxidation (LPO) levels and superoxide anion overproduction, adult mussels experienced more pronounced effects, particularly under simultaneous exposure to low pH and UV-filters. Specifically, the adults exhibited distinct bioconcentration patterns under low pH, along with enhanced cellular metabolic activity and energy-demand compensatory processes, activation of biotransformation pathways, and regulation of antioxidant defenses. Given the ecological and socio-economic importance of M. galloprovincialis and its demonstrated vulnerability to these stressors, these findings highlight the need for further studies on potential transgenerational impacts and evolutionary implications for mussel populations.
Continue reading ‘Impacts of UV-filter pollution and low pH: sperm and adult biomarkers in the mussel Mytilus galloprovincialis in a multi-stressor context’Effects of single or combined exposure to tralopyril and ocean acidification on energy metabolism response and sex development in Pacific oysters (Crassostrea gigas)
Published 5 November 2024 Science ClosedTags: biological response, laboratory, mollusks, multiple factors, physiology, reproduction, toxicants
Highlights
- Tralopyril and OA stimulate energy metabolism gene expression in the C. gigas.
- Under the stress of ocean acidification, C. gigas tend to develop into females.
- C. gigas are able to restore normal energy metabolism from a state of stress after depuration.
Abstract
The combined effects of the novel antifouling biocide tralopyril (TP) nitrile and ocean acidification (OA) on marine organisms are still not well understood, despite the increasing attention given to the toxic effects of emerging pollutants and OA on marine organisms in recent years. In this study, Crassostrea gigas (C. gigas) was exposed to TP, OA, and a combination of TP and OA for 21 days with a 14-day depuration. This study investigated the inter-tissue variability in energy metabolism responses and the impacts on gonadal development in C. gigas under both single and combined exposures to TP and OA. The results indicate that TP exposure and OA resulted in up-regulation of energy metabolism genes in the C. gigas, with tissues exhibiting enhanced aerobic metabolism. Furthermore, OA influences the sex determination of C. gigas, promoting the development of female individuals. Moreover, following depuration, C. gigas is able to restore normal energy metabolism and sexual development through the accumulation of suitable energy reserves. This study provides a valuable reference for the environmental and ecological risk assessment of TP, addressing the research gap in understanding the combined toxicity of TP and OA on aquatic organisms.
Continue reading ‘Effects of single or combined exposure to tralopyril and ocean acidification on energy metabolism response and sex development in Pacific oysters (Crassostrea gigas)’Environmental behavior and toxic effects of micro(nano)plastics and engineered nanoparticles on marine organisms under ocean acidification: a review
Published 5 November 2024 Science ClosedTags: biological response, BRcommunity, growth, morphology, multiple factors, physiology, reproduction, review, toxicants
Ocean acidification (OA) driven by human activities and climate change presents new challenges to marine ecosystems. At the same time, the risks posed by micro(nano)plastics (MNPs) and engineered nanoparticles (ENPs) to marine ecosystems are receiving increasing attention. Although previous studies have uncovered the environmental behavior and the toxic effects of MNPs and ENPs under OA, there is a lack of comprehensive literature reviews in this field. Therefore, this paper reviews how OA affects the environmental behavior of MNPs and ENPs, and summarizes the effects and the potential mechanisms of their co-exposure on marine organisms. The review indicates that OA changes the marine chemical environment, thereby altering the behavior of MNPs and ENPs. These changes affect their bioavailability and lead to co-exposure effects. This impacts marine organisms’ energy metabolism, growth and development, antioxidant systems, reproduction and immunity. The potential mechanisms involved the regulation of signaling pathways, abnormalities in energy metabolism, energy allocation, oxidative stress, decreased enzyme activity, and disruptions in immune and reproductive functions. Finally, based on the limitations of existing research, actual environment and hot issues, we have outlined future research needs and identified key priorities and directions for further investigation. This review deepens our understanding of the potential effects of MNPs and ENPs on marine organisms under OA, while also aiming to promote further research and development in related fields.
Continue reading ‘Environmental behavior and toxic effects of micro(nano)plastics and engineered nanoparticles on marine organisms under ocean acidification: a review’
