Conflicting results remain on how climate change affects the biological performance of different marine taxa, hindering our capacity to predict the future state of marine ecosystems. Using a novel meta-analytical approach, we tested for directional changes and deviations across biological responses of fish and invertebrates from exposure to warming (OW), acidification (OA), and their combination. In addition to the established effects of climate change on calcification, survival and metabolism, we found deviations in the physiology, reproduction, behavior, and development of fish and invertebrates, resulting in a doubling of responses significantly affected when compared to directional changes. Widespread deviations of responses were detected even under moderate (IPCC RCP6-level) OW and OA for 2100, while directional changes were mostly limited to more severe (RCP 8.5) exposures. Because such deviations may result in ecological shifts impacting ecosystem structure and processes, our results suggest that OW and OA will likely have stronger impacts than those previously predicted based on directional changes alone.
Continue reading ‘Hidden impacts of climate change on biological responses of marine life’Posts Tagged 'biological response'
Hidden impacts of climate change on biological responses of marine life
Published 28 September 2023 Science Leave a CommentTags: biological response, calcification, community composition, growth, morphology, mortality, otherprocess, performance, physiology, reproduction, review
Subtle effect of ocean acidification on the larval development of the Nudibranch aeolidiella glauca (Nudibranchia, Gastropoda)
Published 28 September 2023 Science Leave a CommentTags: biological response, laboratory, mollusks, morphology, North Atlantic, performance
The body of knowledge on ocean acidification gives a better understanding of biological sensitivity to low pH. Key parameters such as life-history strategies or local adaptation were identified as keys to predict species sensitivity and resolve previously some of the unexplained species- and population-specific differences. Encapsulation has been suggested as one of these keys as it exposed the embryo to low pH conditions, or ontogenetic hypercapnia, leading to physiological adaptation. We tested this hypothesis on the nudibranch Aeolidiella glauca by exposing their egg-strings containing large number of eggs to two different pH (8.1 and 7.3). The fertilized eggs developed 1 egg-cell, over early cleavage up to morula, blastula, gastrula, rhomboid-shaped rotating gastrula, early rotating veliger larvae with developed shell, to free-swimming well developed veliger larvae. Despite a corrosive environment, the exposure to low pH had no significant effect on the developmental rate. The only significant effects were a slightly smaller and narrower shell in larvae raised at low pH as compared to the high pH. Our results showed a remarkable resilient to low pH in a calcifying mollusc and support the idea that ontogenic hypercapnia is leading to low sensitivity to ocean acidification.
Continue reading ‘Subtle effect of ocean acidification on the larval development of the Nudibranch aeolidiella glauca (Nudibranchia, Gastropoda)’Impact of ocean acidification on bioactive compounds production by marine phytoplankton, Off Visakhapatnam, Bay of Bengal
Published 27 September 2023 Science Leave a CommentTags: biological response, Indian, laboratory, mesocosms, nitrogen fixation, photosynthesis, physiology, phytoplankton
Shallow coastal regions face heightened vulnerability due to human development, making them susceptible to substantial influxes of human-caused inputs alongside waters with low pH levels. This research delved into a microcosm pH alteration experiment to explore the impact of pH reduction on the generation of bioactive substances by marine phytoplankton in the eutrophic coastal waters of the Bay of Bengal. Initially, the prevalent compounds in the surface seawater were fucoxanthin at 75%, zeaxanthin at 10%, and other bioactive elements like diadinoxanthin, diatoxanthin, and β-carotene collectively contributing to around 15%. Notably, all bioactive compounds and Chl-a concentrations significantly favored the control container (ranging from 35–70%), while the least growth occurred in the more acidified experimental containers (15–40%).
In alignment with the above findings, the nutrient uptake rates were comparably diminished in the acidified experimental containers compared to the control group. The ratio between protective bioactive compounds (Diato + Diadino + Zea + β-Car) and synthetic bioactive compounds (Fuco + Chl-a) varied from 0.03 to 0.8, with the control container exhibiting the lowest values, and the more acidified experimental containers displaying the highest values of significance. Similarly, the DT index (diatoxanthin / (diatoxanthin + diadinoxanthin)) ratios followed a parallel pattern, with the control container showing the lowest average ratios and the acidified experimental containers displaying the highest ratios. Furthermore, based on our current study, we postulated that acidified water stimulates the proliferation of carotenoid-based bioactive compounds in marine regions more prominently than their synthetic counterparts. Mainly, the production of bioactive compounds in these experiments could also be influenced by our acidification method.
Continue reading ‘Impact of ocean acidification on bioactive compounds production by marine phytoplankton, Off Visakhapatnam, Bay of Bengal’Impact of ocean acidification on shells of the abalone species Haliotis diversicolor and Haliotis discus hannai
Published 27 September 2023 Science Leave a CommentTags: biological response, laboratory, mollusks, morphology, North Pacific, physiology
Ocean acidification (OA) results from the absorption of anthropogenic CO2 emissions by the ocean and threatens the survival of many marine calcareous organisms including molluscs. We studied OA effects on adult shells of the abalone species Haliotis diversicolor and Haliotis discus hannai that were exposed to three pCO2 conditions (ambient, ∼880, and ∼1600 μatm) for 1 year. Shell periostracum corrosion under OA was observed for both species. OA reduced shell hardness and altered the nacre ultrastructure in H. diversicolor, making its shells more vulnerable to crushing force. OA exposure did not reduce the shell hardness of H. discus hannai and did not alter nacre ultrastructure. However, the reduced calcification also decreased its resistance to crushing force. Sr/Ca in the shell increased with rising calcification rate. Mg/Ca increased upon OA exposure could be due to a complimentary mechanism of preventing shell hardness further reduced. The Na/Ca distribution between the aragonite and calcite of abalone shells was also changed by OA. In general, both abalone species are at a greater risk in a more acidified ocean. Their shells may not provide sufficient protection from predators or to transportation stress in aquaculture.
Continue reading ‘Impact of ocean acidification on shells of the abalone species Haliotis diversicolor and Haliotis discus hannai’Impacts of ocean acidification on physiology and ecology of marine invertebrates: a comprehensive review
Published 26 September 2023 Science Leave a CommentTags: biological response, calcification, growth, molecular biology, performance, physiology, reproduction, review
Ocean acidification (OA) arises as a consequence of excessive carbon dioxide (CO2) inputs into the ocean, a situation further exacerbated by anthropogenic gas emissions. Predictions indicate that seawater surface pH will decrease by 0.4 by the end of the twenty-first century. Notably, studies have observed significant alterations in molluscan assemblages due to OA, leading to a substantial decline of 43% in species richness and 61% in overall mollusc abundance. Moreover, OA has been associated with a 13 ± 3% reduction in the skeletal density of massive Porites corals on the Great Barrier Reef since 1950, particularly affecting marine invertebrates. Given these impacts, this review aims to comprehensively assess the research status and main effects of OA on the physiology and ecology of marine invertebrates over the past two decades, employing bibliometric analysis. Additionally, this review aims to offer valuable insights into potential future research directions. The analysis reveals that research on OA and its influence on marine invertebrates is predominantly conducted in Europe, America, and Australia, reflecting the local extent of acidification and the characteristics of species in these regions. OA significantly affects various physiological aspects of marine invertebrates, encompassing the calcification process, oxidative stress, immunity, energy budget, metabolism, growth, development, and genetics, consequently impacting their behaviour and causing disruptions in the population structure and marine ecosystem. As a result, future research should aim to intimately connect the different physiological mechanisms of marine invertebrates with comprehensive ecosystem evaluation, such as investigating the relationships between food webs, abiotic factors, energy, and matter flow. Furthermore, it is crucial to explore the interactive effects of OA with other stressors, assess the potential for adaptation and acclimation in marine invertebrates, and evaluate the broader ecological implications of OA on entire marine ecosystems. Emphasizing these aspects in future studies will contribute significantly to our understanding of OA’s impact on marine invertebrates and facilitate effective conservation and management strategies for these vital biological communities within marine ecosystems.
Continue reading ‘Impacts of ocean acidification on physiology and ecology of marine invertebrates: a comprehensive review’Transgenerational adaptation to ocean acidification determines the susceptibility of filter-feeding rotifers to nanoplastics
Published 26 September 2023 Science Leave a CommentTags: biological response, laboratory, molecular biology, multiple factors, North Pacific, performance, physiology, toxicants, zooplankton
The adaptation of marine organisms to the impending challenges presented by ocean acidification (OA) is essential for their future survival, and mechanisms underlying OA adaptation have been reported in several marine organisms. In the natural environment, however, marine organisms are often exposed to a combination of environmental stressors, and the interactions between adaptive responses have yet to be elucidated. Here, we investigated the susceptibility of filter-feeding rotifers to short-term (ST) and long-term (LT) (≥180 generations) high CO2 conditions coupled with nanoplastic (NPs) exposure (ST+ and LT+). Adaptation of rotifers to elevated CO2 caused differences in ingestion and accumulation of NPs, resulting in a significantly different mode of action on in vivo endpoints between the ST+ and LT+ groups. Moreover, microRNA-mediated epigenetic regulation was strongly correlated with the varied adaptive responses between the ST+ and LT+ groups, revealing novel regulatory targets and pathways. Our results indicate that pre-exposure history to increased CO2 levels is an important factor in the susceptibility of rotifers to NPs.
Continue reading ‘Transgenerational adaptation to ocean acidification determines the susceptibility of filter-feeding rotifers to nanoplastics’Influence of seagrass on juvenile Pacific oyster growth in two US west coast estuaries with different environmental gradients
Published 25 September 2023 Science Leave a CommentTags: adaptation, biological response, BRcommunity, chemistry, field, growth, mollusks, morphology, North Pacific, otherprocess, performance, photosynthesis, physiology
Ocean acidification threatens many marine organisms, including oysters. Seagrass habitat has been suggested as a potential refuge for oysters because it may ameliorate stressful carbonate chemistry and augment food availability. We conducted an in situ study to investigate whether eelgrass Zostera marina habitat affects the growth of juvenile Pacific oysters Crassostrea gigas and influences local carbonate chemistry or food quantity at sites where we expected contrasting conditions in two US west coast estuaries. Juvenile oysters were out-planted in typical intertidal on-bottom (just above sediment) and off-bottom (45 cm above sediment) culture positions and in adjacent eelgrass and unvegetated habitats from June to September 2019. Water quality was measured with sondes for 24 h periods each month, and discrete water samples were collected in conjuncture. Results show that eelgrass habitat did not alter average local carbonate chemistry (pH, pCO2, Ωcalcite), but consistently reduced available food (relative chlorophyll a). Eelgrass habitat had little to no effect on the shell or tissue growth of juvenile oysters but may have influenced their energy allocation; oysters displayed a 16% higher ratio of shell to tissue growth in eelgrass compared to unvegetated habitat when cultured on-bottom. At the seascape scale, average site-level pH was negatively correlated with shell to tissue growth but not with shell growth alone. Overall, these findings suggest that juvenile oysters may display a compensatory response and allocate more energy to shell than tissue growth under stressful conditions like acidic water and/or altered food supply due to reduced immersion or eelgrass presence.
Continue reading ‘Influence of seagrass on juvenile Pacific oyster growth in two US west coast estuaries with different environmental gradients’Energy metabolism of Mytilus galloprovincialis under low seawater pH (in Russian)
Published 25 September 2023 Science Leave a CommentTags: biological response, Black Sea, laboratory, mollusks, physiology, respiration
The problem of acidification of the World Ocean and predicting the consequences for its inhabitants is becoming more and more relevant every year. The effect of short-term pH fluctuations in coastal ecosystems on the physiology of calcifying organisms—bivalves—remains poorly understood. The energy metabolism of the Black Sea mussel Mytilus galloprovincialis was investigated for the marine environment in a wide pH range, from 8.2 to 6.65. Lowering the pH to 7.0–7.5 led to a 20–25 % reduction in oxygen consumption by molluscs. At lower pH (6.54–6.7), aerobic respiration sharply decreased by 85–90 %, down to the minimum values (2.12–2.62 µgO2 /g dry/h), and the organisms transitioned to anaerobic metabolism. The metabolic response of the mussels subjected to short-term pH changes (8.2→6.65→7.2) has been investigated. The oxygen consumption of molluscs exposed at the same pH of 7.2 depended on the direction of the change in pH. Thus, in the case of pH 6.65→7.2, the respiration intensity was 30 % higher compared to the values obtained under the acidification pH 8.2→7.2. The Black Sea mussel M. galloprovincialis is shown to have the capacity for survival in the marine environment characterized by the rapid fluctuations in pH that occur during the upwelling events in the coastal areas of the Black Sea.
Continue reading ‘Energy metabolism of Mytilus galloprovincialis under low seawater pH (in Russian)’The effect of ocean acidification on otolith morphology in larvae of a tropical, epipelagic fish species, yellowfin tuna (Thunnus albacares)
Published 25 September 2023 Science Leave a CommentTags: biological response, fish, laboratory, morphology, North Pacific
Increasing ocean acidification is a concern due to its potential effects on the growth, development, and survival of early life stages of tuna in oceanic habitats and on the spatial extent of their suitable nursery habitat. To investigate the potential effects of increasing CO2 on otolith calcification of 9-day old pre-flexion stage yellowfin tuna (Thunnus albacares), an experiment was conducted at the Inter-American Tropical Tuna Commission’s Achotines Laboratory in Panama during 2011. Fertilized eggs and larvae were exposed to mean pCO2 levels that ranged from present day (355 μatm) to two levels predicted to occur in some areas of the Pacific in the near future (2013 and 3321 μatm), and to an extreme value equivalent to long-term projections for 300 years in the future (9624 μatm). The results indicated significantly larger otoliths (in area and perimeter) with significant, and increasing, fluctuating asymmetry at acidification levels similar to those projected for the near future and long-term. Otoliths increased significantly in size despite a significant decrease in somatic length with increasing pCO2. A consistent correlation between otolith and somatic growth of yellowfin tuna larvae among treatments was evident (i.e., larger otoliths were still associated with larger larvae within a treatment). The observed changes in otolith morphology with increasing ocean acidification have the potential to indirectly affect larval survival through dysfunction of the mechanosensory organs, but this remains to be verified in yellowfin tuna larvae.
Continue reading ‘The effect of ocean acidification on otolith morphology in larvae of a tropical, epipelagic fish species, yellowfin tuna (Thunnus albacares)’Early life physiological and energetic responses of Atlantic silversides (Menidia menidia) toocean acidification, warming, and hypoxia
Published 22 September 2023 Science Leave a CommentTags: biological response, fish, growth, laboratory, mortality, multiple factors, oxygen, performance, physiology, reproduction, temperature
Global environmental change caused by human actions is making the oceans warmer, deoxygenating coastal waters, and causing acidification through dissolution of atmospheric carbon dioxide (CO2). Understanding physiological mechanisms of fish responses to multiple co-occurring stressors is critical to conservation of marine ecosystems and the fish populations they support. In this dissertation I quantified physiological impacts of near-future levels of multiple stressors in the early life stages of the Atlantic silverside, Menidia menidia. In Chapter 1, I measured routine metabolic rates of embryos and larvae reared in combinations of temperature, CO2, and oxygen levels. An interactive effect of acidification and hypoxia in embryos prompted closer examination in Chapter 2, in which I characterized the relationship between metabolism and acute hypoxia in M. menidia offspring reared in different CO2 levels. In Chapter 3 I examined the density of skin surface ionocytes, cells used for acid-base balance, as an early life mechanism of high CO2 tolerance. The first three chapters highlighted how different CO2 effects could be depending on temperature, oxygen levels, and life stage. They also showed variable, but often high, tolerance of CO2 with stronger effects of temperature and hypoxia on physiology. Finally, in Chapter 4 I used a Dynamic Energy Budget model to identify the processes of energetic allocation responsible for previously observed experimental hypoxia effects on M. menidia hatching, growth, and survival. Energy budget modeling can enhance knowledge about stressor responses by providing the information to link organismal traits to life history and populations, making it more readily applicable to conservation and management. The findings presented here provide a foundation for a more comprehensive understanding of the highly variable effects of global change on M. menidia and should be applied to quantifying impacts on fitness and population growth in this ecologically important species.
Continue reading ‘Early life physiological and energetic responses of Atlantic silversides (Menidia menidia) toocean acidification, warming, and hypoxia’Seasonality of marine calcifiers in the northern Barents Sea: spatiotemporal distribution of planktonic foraminifers and shelled pteropods and their contribution to carbon dynamics
Published 22 September 2023 Science Leave a CommentTags: abundance, Arctic, biological response, chemistry, field, mollusks, morphology, otherprocess, physiology, primary production, protists
Highlights
- In the northern Barents Sea there is a seasonal pattern of production and size distribution of planktonic foraminifers and pteropods, increasing from winter (March) to summer (July–August) and late autumn (December).
- In general, pteropods dominate over planktonic foraminifera in the Arctic influenced stations.
- In the study area, pteropods contribute the most (>80%) to carbon standing stocks and export production.
- The highest values of carbon standing stocks and export production were found in the seasonal ice zone during all seasons.
Abstract
The Barents Sea is presently undergoing rapid warming and the sea-ice edge and the productive zones are retreating northward at accelerating rates. Planktonic foraminifers and shelled pteropods are ubiquitous marine calcifiers that play an important role in the carbon budget and being particularly sensitive to ocean biogeochemical changes and ocean acidification. Their distribution at high latitudes have rarely been studied, and usually only for the summer season. Here we present results of their distribution patterns in the upper 300 m in the water column (individuals m−3), protein content and size distribution on a seasonal basis to estimate their inorganic and organic carbon standing stocks (µg m−3) and export production (mg m−2 d−1). The study area constitutes a latitudinal transect in the northern Barents Sea from 76˚ N to 82˚ N including seven stations through both Atlantic, Arctic, and Polar surface water regimes and the marginal and seasonal sea-ice zones. The transect was sampled in 2019 (August and December) and 2021 (March, May, and July). The highest carbon standing stocks and export production were found at the Polar seasonally sea-ice covered shelf stations with the contribution from shelled pteropods being significantly higher than planktonic foraminifers during all seasons. We recorded the highest production of foraminifers and pteropods in summer (August 2019 and July 2021) and autumn (December 2019) followed by spring (May 2021), and the lowest in winter (March 2021).
Continue reading ‘Seasonality of marine calcifiers in the northern Barents Sea: spatiotemporal distribution of planktonic foraminifers and shelled pteropods and their contribution to carbon dynamics’The synergistic negative effects of combined acidification and warming on the coral host and its symbiotic association with Symbiodiniaceae indicated by RNA-Seq differential expression analysis
Published 21 September 2023 Science Leave a CommentTags: algae, biological response, corals, laboratory, molecular biology, multiple factors, North Pacific, temperature
Global warming and ocean acidification represent major threats to coral reefs, the combination of these stressors may have concomitant impacts on coral holobionts. However, the molecular mechanisms of the impacts and synergistic effects of acidification and warming on coral holobionts are rarely known, particularly from the point of coral-Symbiodiniaceae symbioses. In this study, using branching Acropora valida and massive Galaxea fascicularis as representatives in a laboratory system simulating acidification (pH 7.7) and/or warming (32 °C), the response of coral host, Symbiodiniaceae and their symbiotic association were investigated by high-throughput transcriptome sequencing (RNA-Seq) with pH 8.1 and 26 °C as controls. Based on differentially expressed genes (DEGs) analysis, acidification and/or warming show greater impacts on the gene expression of coral host than its symbiotic Symbiodiniaceae. Synergistic effects of combined acidification and warming are suggested by comparison with single stress, especially the synergistic negative effects on coral-Symbiodiniaceae symbioses are suggested, because the expression of most of the genes related to photosynthesis, nutrient metabolism and transfer, and the symbionts recognition are downregulated indicating the instability of the coral-Symbiodiniaceae symbioses. This study provides molecular evidence for the synergy of acidification and warming on coral holobionts. In particular, the synergistic negative effects on the nutrients and symbionts recognition-based coral-Symbiodiniaceae symbioses are highlighted, which is helpful for predicting the response of coral holobionts to future global climate changes.
Continue reading ‘The synergistic negative effects of combined acidification and warming on the coral host and its symbiotic association with Symbiodiniaceae indicated by RNA-Seq differential expression analysis’Elucidating the mechanisms of stress tolerance in reef-building coral holobionts
Published 21 September 2023 Science Leave a CommentTags: abundance, algae, biological response, corals, growth, laboratory, molecular biology, mortality, multiple factors, otherprocess, photosynthesis, physiology, temperature
Coral reefs worldwide are threatened by climate change effects like increasing ocean warming and ocean acidification. These increased pressures cause a dysbiosis between the coral host, algal endosymbionts, and associated coral microbiome that results in the coral host expelling algal endosymbionts, leaving the coral host with a stark white ‘bleached’ appearance. Without their endosymbionts, coral hosts are forced to sustain themselves energetically with heterotrophy instead of relying on the autotrophic carbon and energy sources that once came from the algal endosymbionts. When this response, termed ‘coral bleaching’, happens reef-wide during an extreme wave of increased ocean temperatures, this is called a mass Coral Bleaching Event. The frequency and intensity of mass Coral Bleaching events are increasing around the world, forcing corals to acclimatize to survive. This dissertation investigates the physiological and genomic mechanisms underlying acclimatization and increased stress tolerance in two common, reef-building corals: Montipora capitata and Pocillopora acuta. In three chapters, I present findings that support phenotypic plasticity and increased stress tolerance in M. capitata and hypothesize the mechanisms contributing to this. In Chapter 1, I conducted an ex-situ experiment that mimicked an environmentally realistic, extended heatwave and ocean acidification scenario in a factorial design of increased temperature and increased pCO2 conditions for a two-month stress period and a two-month recovery period. Both species’ physiological states were significantly challenged but M. capitata displayed a more favorable photosynthetic rate to antioxidant capacity ratio and associated with more thermally tolerant symbionts. Although M. capitata survived at higher rates than P. acuta, physiological state was still significantly impacted after two months of recovery, suggesting that marine heatwaves likely induce physiological legacies that may impact performance during the next, inevitable heatwave. In Chapter 2, I further investigated P. acuta’s stress response from Chapter 1 at a genomic level. We sought to test the effects of environmental stressors on gene body DNA methylation patterns to elucidate how environmentally sensitive and dynamic DNA methylation changes are in invertebrates. However, when analyzing gene expression data, our team found that polyploidy was prevalent in our samples, which convoluted our ability to test environmental effect in addition to polyploidy structure. We found that DNA methylation patterns followed polyploidy genetic lineage with diploid corals exhibiting the highest levels of DNA methylation despite lower gene expression levels of epigenetic machinery proteins. Despite significant DNA methylation pattern differences between polyploidies, P. acuta populations still severely declined in increased stress conditions (outlined in Chapter 1), suggesting that regardless of differential gene body methylation and ploidy status, this species may be ultimately too sensitive to future ocean conditions. In Chapter 3, I further investigated the genomic mechanisms underlying stress response in Montipora capitata, by directly comparing bleached (‘Susceptible’) and non-bleached (‘Resistant’) phenotypes of conspecific pairs. We found very little genetic diversity among our samples suggesting there is no effect of genetic structure on phenotypic variation in this context. ‘Resistant’ corals were characterized by association with more thermally tolerant symbionts, lower gene expression variability, higher gene body methylation levels on genes involved in death and stress response, and a more robust cellular stress response. The results of all three chapters suggest that both physiological and genomic stats impact bleaching susceptibility and phenotype and that not one mechanism may act alone to produce a particular phenotype. This dissertation aids in elucidating the mechanisms of stress response in reef-building corals, ultimately guiding our current knowledge of phenotypic variation in the face of climate change.
Continue reading ‘Elucidating the mechanisms of stress tolerance in reef-building coral holobionts’Ocean acidification affects the response of the coastal coccolithophore Pleurochrysis carterae to irradiance
Published 21 September 2023 Science Leave a CommentTags: biological response, growth, laboratory, light, multiple factors, North Pacific, photosynthesis, physiology, phytoplankton, primary production
The ecologically important marine phytoplankton group coccolithophores have a global distribution. The impacts of ocean acidification on the cosmopolitan species Emiliania huxleyi have received much attention and have been intensively studied. However, the species-specific responses of coccolithophores and how these responses will be regulated by other environmental drivers are still largely unknown. To examine the interactive effects of irradiance and ocean acidification on the physiology of the coastal coccolithophore species Pleurochrysis carterae, we carried out a semi-continuous incubation experiment under a range of irradiances (50, 200, 500, 800 μmol photons m−2 s−1) at two CO2 concentration conditions of 400 and 800 ppm. The results suggest that the saturation irradiance for the growth rate was higher at an elevated CO2 concentration. Ocean acidification weakened the particulate organic carbon (POC) production of Pleurochrysis carterae and the inhibition rate was decreased with increasing irradiance, indicating that ocean acidification may affect the tolerating capacity of photosynthesis to higher irradiance. Our results further provide new insight into the species-specific responses of coccolithophores to the projected ocean acidification under different irradiance scenarios in the changing marine environment.
Continue reading ‘Ocean acidification affects the response of the coastal coccolithophore Pleurochrysis carterae to irradiance’Impacts of ocean warming and acidification on predator-prey interactions in the intertidal zone: a research weaving approach
Published 20 September 2023 Science Leave a CommentTags: biological response, multiple factors, performance, review, temperature
The effect of ocean warming and acidification on predator-prey interactions in the intertidal zone is a topic of growing concern for the scientific community. In this review, we aim to describe how scientists have explored the topic via research weaving, a combination of a systematic review, and a bibliometric approach. We assess articles published in the last decade exploring the impact of both stressors on predation in the intertidal zone, via experimental or observational techniques. Several methods were used to delve into how climate change-induced stress affected intertidal predation, as the study design leaned toward single-based driver trials to the detriment of a multi-driver approach. Mollusks, echinoderms, and crustaceans have been extensively used as model organisms, with little published data on other invertebrates, vertebrates, and algae taxa. Moreover, there is a strong web of co-authoring across institutions and countries from the Northern Hemisphere, that can skew our understanding towards temperate environments. Therefore, institutions and countries should increase participation in the southern hemisphere networking, assessing the problems under a global outlook. Our review also addresses the various impacts of ocean acidification, warming, or their interaction with predation-related variables, affecting organisms from the genetic to a broader ecological scope, such as animal behaviour or interspecific interactions. Finally, we argue that the numerous synonyms used in keywording articles in the field, possibly hurting future reviews in the area, as we provide different keyword standardizations. Our findings can help guide upcoming approaches to the topic by assessing what has been already done and revealing gaps in emerging themes, like a strong skew towards single-driver (specially acidification) lab experiments of northern hemisphere organisms and a lack of field multi-stressor experiments.
Continue reading ‘Impacts of ocean warming and acidification on predator-prey interactions in the intertidal zone: a research weaving approach’Fermentative iron reduction buffers acidification and promotes microbial metabolism in marine sediments
Published 19 September 2023 Science Leave a CommentTags: abundance, biological response, BRcommunity, chemistry, laboratory, mitigation, North Pacific, otherprocess, physiology, prokaryotes, sediment
Microbial iron reduction is a crucial process in natural ecosystems, contributing to the cycling of elements and supporting the biological activities of organisms. However, the significance of fermentative iron reduction in marine environments and microbial metabolism remains understudied compared with iron reduction coupled with respiration. The main objective of our study was to investigate the influence of fermentative iron reduction on microbial populations and marine sediment. Our findings revealed a robust iron-reducing activity in the enriched marine sediment, demonstrating a maximum ferrihydrite-reducing rate of 0.063 mmol/h. Remarkably, ferrihydrite reduction exhibited an intriguing pH-buffering effect through the release of OH+ and Fe2+ ions, distinct from fermentation alone. This effect resulted in substantial improvements in glucose consumption (71.4%), bacterial growth (48.1%), and metabolite production (80.8%). To further validate the acidification-buffering and metabolism-promoting effects of ferrihydrite reduction, we conducted iron-reducing experiments using a pure strain, Clostridium pasteurianum DMS525. The observed pH-buffering effect resulted from microbial iron reduction in marine sediment and has potential environmental implications by reducing CO2 emissions, mitigating acidification, and preserving the delicate balance of marine ecosystems.
Continue reading ‘Fermentative iron reduction buffers acidification and promotes microbial metabolism in marine sediments’The estuarine environment and pH variation: natural limits and experimental observation of the acidification effect on phosphorus bioavailability (in Portuguese)
Published 14 September 2023 Science ClosedTags: biogeochemistry, biological response, chemistry, field, sediment, South Pacific
This study shows the variation of pH in the Cananéia-Iguape Estuarine-Lagoon Complex (CIELC). Data from 3 years (2019, 2021, 2022) were obtained in 17 points presenting the following ranges: temperature (14.88-27.05 ºC), pH (7.16-8.40) and DIP (0.20-11.28 µmol L-1) along a saline gradient (0.05-32.09) under different hydrodynamics, biogeochemical processes and anthropogenic influence. The pH buffering capacity due to the presence of weak acid salts in saline water (S ≥ 30) was associated to the lowest DIP, decreasing with low salinity values, confirming the direct correlation among salinity and pH. The highest temperatures in the winter of 2021, corroborated with the abnormal climate event in that year. An in vitro experiment showed results of the interaction of PID and sediments with different textures, with and without the presence of the benthic microbiota under a considerable decreasing of the pH (acidification) in relation to the natural condition of this environment. The P sediment flux characterized Iguape sector as a P sink with or without biota, Ararapira sector as a P source with biota and Cananéia, as P source without biota. The salt water buffered the pH and sediment buffered DIP both associated to the biogeochemical and hydrodynamic processes contribute to the homeostasis in the system.
Continue reading ‘The estuarine environment and pH variation: natural limits and experimental observation of the acidification effect on phosphorus bioavailability (in Portuguese)’Ocean acidification reduces iodide production by the marine diatom Chaetoceros sp. (CCMP 1690)
Published 13 September 2023 Science ClosedTags: biological response, growth, Indian, laboratory, physiology, phytoplankton
Highlights
- Ocean acidification had no effect on growth rates of the diatom Chaetoceros sp. CCMP (1690) but higher cell yield under high CO2.
- Ocean acidifcation has the potential to inhibit the diatom-mediated iodate to iodide reduction process.
- Iodide production was decoupled from iodate uptake and refute the proposed link between iodide produced and cell membrane permeability.
Abstract
Phytoplankton in marine surface waters play a key role in the global iodine cycle. The biologically-mediated iodide production under future scenarios is limited. Here we compare growth, iodate to iodide conversion rate and membrane permeability in the diatom Chaetoceros sp. (CCMP 1690) grown under seawater carbonate chemistry conditions projected for 2100 (1000 ppm) and pre-industrial (280 ppm) conditions. We found no effect of CO2 on growth rates, but a significantly higher cell yield under high CO2, suggesting sustained growth from relief from carbon limitation. Cell normalised iodate uptake (16.73 ± 0.92 amol IO3− cell−1) and iodide production (8.61 ± 0.15 amol I− cell−1) was lower in cultures grown at high pCO2 than those exposed to pre-industrial conditions (21.29 ± 2.37 amol IO3− cell−1, 11.91 ± 1.49 amol I− cell−1, respectively). Correlating these measurements with membrane permeability, we were able to ascertain that iodide conversion rates were not linked to cell permeability and that the processes of mediated iodate loss and diatom-iodide formation are decoupled. These findings are the first to implicate OA in driving a potential shift in diatom-mediated iodate reduction. If our results are indicative of diatom-mediated iodine cycling in 2100, future surface ocean conditions could experience reduced rates of iodide production by Chaetoceros spp., potentially lowering iodide concentrations in ocean regions dominated by this group. These changes have the potential to impact ozone cycling and new particle formation in the atmosphere.
Continue reading ‘Ocean acidification reduces iodide production by the marine diatom Chaetoceros sp. (CCMP 1690)’The combined effect of pH and dissolved inorganic carbon concentrations on the physiology of plastidic ciliate Mesodinium rubrum and its cryptophyte prey
Published 13 September 2023 Science ClosedTags: biological response, growth, laboratory, North Atlantic, photosynthesis, physiology, phytoplankton, protists
Ocean acidification is caused by rising atmospheric partial pressure of CO2 (pCO2) and involves a lowering of pH combined with increased concentrations of CO2 and dissolved in organic carbon in ocean waters. Many studies investigated the consequences of these combined changes on marine phytoplankton, yet only few attempted to separate the effects of decreased pH and increased pCO2. Moreover, studies typically target photoautotrophic phytoplankton, while little is known of plastidic protists that depend on the ingestion of plastids from their prey. Therefore, we studied the separate and interactive effects of pH and DIC levels on the plastidic ciliate Mesodinium rubrum, which is known to form red tides in coastal waters worldwide. Also, we tested the effects on their prey, which typically are cryptophytes belonging to the Teleaulax/Plagioslemis/Geminigera species complex. These cryptophytes not only serve as food for the ciliate, but also as a supplier of chloroplasts and prey nuclei. We exposed M. rubrum and the two cryptophyte species, T. acuta, T. amphioxeia to different pH (6.8 – 8) and DIC levels (∼ 6.5 – 26 mg C L-1) and assessed their growth and photosynthetic rates, and cellular chlorophyll a and elemental contents. Our findings did not show consistent significant effects across the ranges in pH and/or DIC, except for M. rubrum, for which growth was negatively affected only by the lowest pH of 6.8 combined with lower DIC concentrations. It thus seems that M. rubrum is largely resilient to changes in pH and DIC, and its blooms may not be strongly impacted by the changes in ocean carbonate chemistry projected for the end of the 21th century.
Continue reading ‘The combined effect of pH and dissolved inorganic carbon concentrations on the physiology of plastidic ciliate Mesodinium rubrum and its cryptophyte prey’Predicting the impacts of climate change on New Zealand’s seaweed-based ecosystems
Published 11 September 2023 Science ClosedTags: algae, biological response, BRcommunity, review, South Pacific
The impacts of global climate change are threatening the health and integrity of New Zealand’s seaweed ecosystems that provide crucial ecological, economic, and cultural benefits. Important species that comprise these ecosystems include canopy forming large brown algae (fucoids and kelp), and understorey species. Here we review current knowledge of the measured impacts of climate change stressors on New Zealand seaweeds. Ocean warming has driven increasing frequencies, durations, and intensities of marine heatwaves globally and in New Zealand. Significant negative impacts resulting from heatwaves have already been observed on New Zealand’s canopy forming brown algae (giant kelp Macrocystis pyrifera and bull kelp Durvillaea spp.). We predict that ongoing ocean warming and associated marine heatwaves will alter the distributional range and basic physiology of many seaweed species, with poleward range shifts for many species. Increased extreme weather events causes accelerated erosion of sediments into the marine environment and re-suspension of these sediments, termed coastal darkening, which has reduced the growth rates and available vertical space on rocky reefs in New Zealand and is predicted to worsen in the future. Furthermore, ocean acidification will reduce the growth and recruitment of coralline algae, this may reduce the settlement success of many marine invertebrate larvae. Mechanistic underpinnings of the effects of multiple drivers occurring in combination is poorly described. Finally, local stressors, such as overfishing, will likely interact with global change in these ecosystems. Thus, we predict very different futures for New Zealand seaweed ecosystems depending on whether they are managed appropriately or not. Given recent increases in sea surface temperatures and the increasing frequency of extreme weather events in some regions of New Zealand, predicting the impacts of climate change on seaweeds and the important communities they support is becoming increasingly important for conserving resilient seaweed ecosystems in the future.
Continue reading ‘Predicting the impacts of climate change on New Zealand’s seaweed-based ecosystems’
