Variability in primary producers’ responses to environmental change may buffer higher trophic levels against shifts in basal resource composition. Then again, in instances where there is a lack of functional redundancy because consumers rely on a few species to meet their energetic requirements at specific times of the year, altered community production dynamics may significantly impact food web resilience. In high-latitude kelp forests, a complementary annual phenology of seaweed production supports coastal marine consumers’ metabolic needs across large seasonal variations in their environment. Yet, marine consumers in these systems may face significant metabolic stress under the pronounced low pH conditions expected in future winters, particularly if they lack the resources to support their increased energetic demands. In this study, we investigate how the growth and nutritional value of three dominant, coexisting macroalgal species found in subpolar kelp forests will respond to ocean acidification and warming in future winter and summer seasons. We find that the three kelps Macrocystis pyrifera, Hedophyllum nigripes, and Neoagarum fimbriatum differ in their vulnerability to future environmental conditions, and that the seasonal environmental context of nutrient and light availability shapes these responses. Our results suggest that poleward fringe populations of M. pyrifera may be relatively resilient to anticipated ocean warming and acidification. In contrast, ocean warming conditions caused a decrease in the biomass and nutritional quality of both understory kelps. Considering the unique production phenology of H. nigripes, we emphasize that negative impacts on this species in future winters may be of consequence to consumer energetics in this system. This work highlights how interspecific variation in autotrophs’ responses to global change can disrupt the diversity and phenological structure of energy supply available to higher trophic levels.
Continue reading ‘Season influences interspecific responses of canopy-forming kelps to future warming and acidification at high latitude’Posts Tagged 'growth'
Season influences interspecific responses of canopy-forming kelps to future warming and acidification at high latitude
Published 26 January 2024 Science ClosedTags: algae, biological response, growth, laboratory, morphology, multiple factors, North Pacific, performance, physiology, temperature
Functional changes across marine habitats due to ocean acidification
Published 15 January 2024 Science ClosedTags: abundance, biological response, BRcommunity, calcification, chemistry, community composition, communitymodeling, field, growth, Mediterranean, modeling, otherprocess, performance, photosynthesis, reproduction, vents
Global environmental change drives diversity loss and shifts in community structure. A key challenge is to better understand the impacts on ecosystem function and to connect species and trait diversity of assemblages with ecosystem properties that are in turn linked to ecosystem functioning. Here we quantify shifts in species composition and trait diversity associated with ocean acidification (OA) by using field measurements at marine CO2 vent systems spanning four reef habitats across different depths in a temperate coastal ecosystem. We find that both species and trait diversity decreased, and that ecosystem properties (understood as the interplay between species, traits, and ecosystem function) shifted with acidification. Furthermore, shifts in trait categories such as autotrophs, filter feeders, herbivores, and habitat-forming species were habitat-specific, indicating that OA may produce divergent responses across habitats and depths. Combined, these findings reveal the importance of connecting species and trait diversity of marine benthic habitats with key ecosystem properties to anticipate the impacts of global environmental change. Our results also generate new insights on the predicted general and habitat-specific ecological consequences of OA.
Continue reading ‘Functional changes across marine habitats due to ocean acidification’Thermal fluctuations and CO2 enrichment synergistically accelerate biomass yield of Neopyropia yezoensis
Published 15 January 2024 Science ClosedTags: algae, biological response, growth, laboratory, multiple factors, North Pacific, photosynthesis, physiology, temperature
Due to the rising atmospheric pCO2, the greenhouse effect in the natural environment has intensified, leading to ocean acidification and frequently extreme temperature events. Limited research has been conducted on the effects of near-shore temperature fluctuations and ocean acidification on macroalgae. In this study, Neopyropia yezoensis (Bangiales, Rhodophyta) was cultured under two CO2 concentrations (LC: 400 μatm and HC: 1000 μatm) and three temperature conditions (10 ℃, 14 ℃, and fluctuation: increased from 10 ℃ to 14 ℃ and then decreased back to 10 ℃ with a fluctuation of 1 ℃ per day). The growth, chlorophyll fluorescence, photosynthetic pigments, and soluble carbohydrate of N. yezoensis were measured. The results showed that the relative growth rate, rETRmax, contents of chlorophyll a, phycoerythrin, and carotenoid in the thalli increased at 14 ℃ and thermal fluctuation, while the content of soluble carbohydrate were inhibited. Moreover, the effect of pCO2 on growth was significant only under temperature fluctuation. Even when the temperature dropped to 10 ℃, the physiological responses of N. yezoensis were still promoted by the thermal fluctuation condition. These findings indicate that the yield and quality of N. yezoensis could potentially improve in the future warming scenarios, and changes observed in N. yezoensis could serve as an early indicator for global climate change.
Continue reading ‘Thermal fluctuations and CO2 enrichment synergistically accelerate biomass yield of Neopyropia yezoensis’Inferring the health of coral reefs on the Egyptian coast of the Gulf of Aqaba for three branching-coral species
Published 9 January 2024 Science ClosedTags: biological response, chemistry, corals, field, growth, Red Sea
Abstract
This investigation examined the vulnerability of three branching coral species (Acropora humilis, Pocillopora damicornis, and Stylophora pistillata) to environmental changes within the marine reserves of Taba, Nuweiba, and Dahab in the Gulf of Aqaba. Coral growth rates were assessed as a key indicator of coral reef vitality, reacting to shifting physicochemical parameters. A. humilis manifested the highest growth rate, followed by S. pistillata and P. damicornis. Site-specific data analysis found Dahab displayed the greatest coral proliferation, with Taba exhibiting the least. Accounting for seasonal changes, spring showed maximal coral growth. Statistical analysis revealed a positive correlation between salinity and coral growth rate, contrasted by a negative correlation with variables such as pH, PO4-P, and silicate (SiO4-Si). This work underscores the significant influence of environmental factors on coral growth rates, and by extension, the health of coral reef ecosystems. These findings are integral to coral reef management, suggesting mitigation of adverse environmental factors could enhance these ecosystems’ resilience against climatic shifts and human-induced stressors. By combining species, site, seasonal, and physicochemical variations, this research underlines the importance of localized conservation strategies.
Highlights
- Robust Reef Health: The paper’s findings reveal a remarkable resilience and overall good health of coral reefs in Egypt’s protected marine environments, even when compared to reefs in more polluted and anthropogenically impacted areas.
- Effective Protection Measures: The study underscores the importance of the protective measures implemented in these marine preserves, indicating that they have played a crucial role in maintaining the health and status of the intricate and invaluable reef ecosystems.
- Catalyst for Further Research: The research outcomes provide a strong foundation for future studies aimed at identifying and implementing effective protective measures and adaptive management strategies for coral reefs in diverse ecosystems, with the goal of ensuring their long-term health and preservation.
- Highlighting Environmental Challenges: The paper emphasizes the relative health of the studied coral reefs despite broader environmental challenges, shedding light on the potential success of conservation efforts within these specific marine regions.
Future warming stimulates growth and photosynthesis in an Arctic microalga more strongly than changes in light intensity or pCO2
Published 20 December 2023 Science ClosedTags: Arctic, biological response, growth, laboratory, light, multiple factors, photosynthesis, physiology, phytoplankton, primary production, temperature
We assessed the responses of solitary cells of Arctic Phaeocystis pouchetii grown under a matrix of temperature (2°C vs. 6°C), light intensity (55 vs. 160 μmol photons m−2 s−1) and pCO2 (400 vs. 1000 μatm CO2, i.e., 40.5 vs. 101.3 Pa). Next to acclimation parameters (growth rates, particulate and dissolved organic C and N, Chlorophyll a content), we measured physiological processes in vivo (electron transport rates and net photosynthesis) using fast-repetition rate fluorometry and membrane-inlet mass spectrometry. Within the applied driver ranges, elevated temperature had the most pronounced impacts, significantly increasing growth, elemental quotas and photosynthetic performance. Light stimulations manifested more prominently under 6°C, underlining temperature’s role as a “master-variable”. pCO2 was the least effective driver, exerting mostly insignificant effects. The obtained data were used for a simplistic upscaling simulation to investigate potential changes in P. pouchetii‘s bloom dynamics in the Fram Strait with increasing temperatures over the 21st century. Although solitary cells might not be fully representative of colonial cells commonly observed in the field, our results suggest that global warming accelerates bloom dynamics, with earlier onsets of blooms and higher peak biomasses. Such a temperature-induced acceleration in the phenology of Phaeocystis and likely other Arctic phytoplankton might cause temporal mismatches, e.g., with the development of grazers, and therefore substantially affect the biogeochemistry and ecology of the Arctic.
Continue reading ‘Future warming stimulates growth and photosynthesis in an Arctic microalga more strongly than changes in light intensity or pCO2’Physio-biochemical and metabolomic analyses of the agarophyte Gracilaria salicornia indicates its tolerance to elevated pCO2 levels
Published 14 December 2023 Science ClosedTags: abundance, algae, biological response, growth, Indian, laboratory, otherprocess, photosynthesis, physiology
Gracilaria salicornia is an agar-producing red macroalga commonly found growing in the intertidal and upper subtidal on various substrates with distribution across the Indo-Pacific. The ability of G. salicornia to survive under harsh conditions suggests potential use as a candidate for sustainable farming and alternative source of livelihood for the local coastal communities under future climate conditions. An earlier study investigated the effects of future predicted pCO2 level on the photosynthesis and respiration of G. salicornia but studies on the metabolomic responses of this alga to constant elevated pCO2 level is lacking. Here, elevated pCO2 level was simulated on G. salicornia for 14 days to compare its growth, photosynthetic efficiency, pigment content, agar properties and metabolite composition under current pCO2 level (∼pH 8.1) and end-of-century future-predicted (∼pH 7.8) pCO2 level. The observed biomass growth, coupled with unaffected photosynthetic parameters and agar-related properties underscore G. salicornia’s ability to adapt to higher pCO2 levels. The modulation of metabolites showcases the alga’s adaptive strategies at elevated pCO2 whereby stress-mediating compounds such as gallic acid and oxalic acid were increased while stress-indicating metabolites such as serine, glycine, and ascorbic acid did not show significant changes. Interestingly, the metabolome profile imply that the alga regulates its metabolism according to culture duration rather than the pCO2 level.
Continue reading ‘Physio-biochemical and metabolomic analyses of the agarophyte Gracilaria salicornia indicates its tolerance to elevated pCO2 levels’Higher temperature, increased CO2, and changing nutrient ratios alter the carbon metabolism and induce oxidative stress in a cosmopolitan diatom
Published 8 December 2023 Science ClosedTags: biological response, growth, laboratory, multiple factors, North Atlantic, nutrients, photosynthesis, physiology, phytoplankton, primary production, respiration, temperature
Phytoplankton are responsible for about 90% of the oceanic primary production, largely supporting marine food webs, and actively contributing to the biogeochemical cycling of carbon. Yet, increasing temperature and pCO2, along with higher dissolved nitrogen: phosphorus ratios in coastal waters are likely to impact phytoplankton physiology, especially in terms of photosynthetic rate, respiration, and dissolved organic carbon (DOC) production. Here, we conducted a full-factorial experiment to identify the individual and combined effects of temperature, pCO2, and N : P ratio on the antioxidant capacity and carbon metabolism of the diatom Phaeodactylum tricornutum. Our results demonstrate that, among these three drivers, temperature is the most influential factor on the physiology of this species, with warming causing oxidative stress and lower activity of antioxidant enzymes. Furthermore, the photosynthetic rate was higher under warmer conditions and higher pCO2, and, together with a lower dark respiration rate and higher DOC exudation, generated cells with lower carbon content. An enhanced oceanic CO2 uptake and an overall stimulated microbial loop benefiting from higher DOC exudation are potential longer-term consequences of rising temperatures, elevated pCO2 as well as shifted dissolved N : P ratios.
Continue reading ‘Higher temperature, increased CO2, and changing nutrient ratios alter the carbon metabolism and induce oxidative stress in a cosmopolitan diatom’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’High light intensity and CO2 enrichment synergistically mitigated the stress caused by low salinity in Pyropia yezoensis
Published 30 November 2023 Science ClosedTags: algae, biological response, growth, laboratory, light, multiple factors, North Pacific, photosynthesis, physiology, salinity
Macroalgae, playing a crucial role in coastal marine ecosystems, are subject to multiple environmental challenges due to tidal and seasonal alterations. In this work, we investigated the physiological responses of Pyropia yezoensis to ocean acidification (ambient CO2 (AC: 400 μatm) and elevated CO2 (HC: 1000 μatm)) under changing salinity (20, 30 psu) and light intensities (50, 100 μmol photons m−2 s−1) by measuring the growth, pigment content, chlorophyll fluorescence, and soluble sugar content. The key results are the following: (1) P. yezoensis exhibited better growth under normal salinity (30 psu) compared to hyposaline conditions (20 psu). (2) Intermediate light intensity increased phycoerythrin content, ultimately enhancing thalli growth without significant changes to the contents of chlorophyll a and carotenoids. (3) Ocean acidification alleviated hyposaline stress by enhancing pigment production in P. yezoensis only at a salinity of 20 psu, highlighting the complex interplay of these environmental factors. These findings indicate that higher light intensities and elevated pCO2 levels could mitigate the stress caused by low salinity.
Continue reading ‘High light intensity and CO2 enrichment synergistically mitigated the stress caused by low salinity in Pyropia yezoensis’Ocean acidification impairs seagrass performance under thermal stress in shallow and deep water
Published 24 November 2023 Science ClosedTags: biological response, field, growth, laboratory, Mediterranean, mesocosms, molecular biology, phanerogams, photosynthesis, physiology
Highlights
- Shallow and deep plants were exposed to ocean acidification and thermal stress;
- Plants were unaffected by ocean acidification when not exposed to thermal stress;
- Ocean acidification reduced plant performance under thermal stress;
- Deep plants showed higher levels of heat stress at genetic and physiological levels;
- Warming may play a key role in structuring future seagrass meadows.
Abstract
Despite the effects of ocean acidification (OA) on seagrasses have been widely investigated, predictions of seagrass performance under future climates need to consider multiple environmental factors. Here, we performed a mesocosm study to assess the effects of OA on shallow and deep Posidonia oceanica plants. The experiment was run in 2021 and repeated in 2022, a year characterized by a prolonged warm water event, to test how the effects of OA on plants are modulated by thermal stress. The response of P. oceanica to experimental conditions was investigated at different levels of biological organization. Under average seawater temperature, there were no effects of OA in both shallow and deep plants, indicating that P. oceanica is not limited by current inorganic carbon concentration, regardless of light availability. In contrast, under thermal stress, exposure of plants to OA increased lipid peroxidation and decreased photosynthetic performance, with deep plants displaying higher levels of heat stress, as indicated by the over-expression of stress-related genes and the activation of antioxidant systems. In addition, warming reduced plant growth, regardless of seawater CO2 and light levels, suggesting that thermal stress may play a fundamental role in the future development of seagrass meadows. Our results suggest that OA may exacerbate the negative effects of future warming on seagrasses.
Continue reading ‘Ocean acidification impairs seagrass performance under thermal stress in shallow and deep water’Short-term ocean acidification decreases pulsation and growth of the widespread soft coral Xenia umbellata
Published 20 November 2023 Science ClosedTags: abundance, biological response, corals, growth, laboratory, morphology, mortality, otherprocess, performance, photosynthesis, physiology, protists, respiration
Coral reefs may experience lower pH values as a result of ocean acidification (OA), which has negative consequences, particularly for calcifying organisms. Thus far, the effects of this global factor have been mainly investigated on hard corals, while the effects on soft corals remain relatively understudied. We therefore carried out a manipulative aquarium experiment for 21 days to study the response of the widespread pulsating soft coral Xenia umbellata to simulated OA conditions. We gradually decreased the pH from ambient (~8.3) to three consecutive 7-day long pH treatments of 8.0, 7.8, and 7.6, using a CO2 dosing system. Monitored response variables included pulsation rate, specific growth rate, visual coloration, survival, Symbiodiniaceae cell densities and chlorophyll a content, photosynthesis and respiration, and finally stable isotopes of carbon (C) and nitrogen (N) as well as CN content. Pulsation decreased compared to controls with each consecutive lowering of the pH, i.e., 17% at pH 8.0, 26% at pH 7.8 and 32% at pH 7.6, accompanied by an initial decrease in growth rates of ~60% at pH 8.0, not decreasing further at lower pH. An 8.3 ‰ decrease of δ13C confirmed that OA exposed colonies had a higher uptake and availability of atmospheric CO2. Coral productivity, i.e., photosynthesis, was not affected by higher dissolved inorganic C availability and none of the remaining response variables showed any significant differences. Our findings suggest that pulsation is a phenotypically plastic mechanism for X. umbellata to adjust to different pH values, resulting in reduced growth rates only, while maintaining high productivity. Consequently, pulsation may allow X. umbellata to inhabit a broad pH range with minimal effects on its overall health. This resilience may contribute to the competitive advantage that soft corals, particularly X. umbellata, have over hard corals.
Continue reading ‘Short-term ocean acidification decreases pulsation and growth of the widespread soft coral Xenia umbellata’The modulating role of natural variability in the biological response to ocean acidification
Published 16 November 2023 Science ClosedTags: abundance, biological response, calcification, echinoderms, growth, laboratory, morphology, mortality, North Atlantic, otherprocess, reproduction
Ocean acidification (OA) is the consequence of the uptake of excess carbon dioxide from the atmosphere. Along the coastal zone, ocean acidification is influenced by other processes such as biology and currents, leading to high levels of natural variability in pH. While the impact of pH on marine organisms is better resolved, the modulating role of this natural variability is poorly understood. This master’s thesis aimed at evaluating diel pH fluctuations using the larval stages of the brittle star Amphiura filiformis. Results revealed the importance of acknowledging pH variations with individuals exhibiting higher fitness. Diel analyses also underscored the existence of an intrinsic circadian cycle where larvae would grow more during the daytime than nighttime, possibly explained by better conditions encountered during the day. In addition, we demonstrated a carryover effect that could also be associated with a stage sensitivity. We suggest that future studies should integrate natural variations and delve into the different species’ adaptations as they have an important role in the biological responses to upcoming OA.
Continue reading ‘The modulating role of natural variability in the biological response to ocean acidification’Short-term acidification promotes diverse iron acquisition and conservation mechanisms in upwelling-associated phytoplankton
Published 14 November 2023 Science ClosedTags: biological response, BRcommunity, chemistry, community composition, field, growth, laboratory, molecular biology, North Pacific, otherprocess, photosynthesis, physiology, phytoplankton
Coastal upwelling regions are among the most productive marine ecosystems but may be threatened by amplified ocean acidification. Increased acidification is hypothesized to reduce iron bioavailability for phytoplankton thereby expanding iron limitation and impacting primary production. Here we show from community to molecular levels that phytoplankton in an upwelling region respond to short-term acidification exposure with iron uptake pathways and strategies that reduce cellular iron demand. A combined physiological and multi-omics approach was applied to trace metal clean incubations that introduced 1200 ppm CO2 for up to four days. Although variable, molecular-level responses indicate a prioritization of iron uptake pathways that are less hindered by acidification and reductions in iron utilization. Growth, nutrient uptake, and community compositions remained largely unaffected suggesting that these mechanisms may confer short-term resistance to acidification; however, we speculate that cellular iron demand is only temporarily satisfied, and longer-term acidification exposure without increased iron inputs may result in increased iron stress.
Continue reading ‘Short-term acidification promotes diverse iron acquisition and conservation mechanisms in upwelling-associated phytoplankton’Role of culture solution pH in balancing CO2 input and light intensity for maximising microalgae growth rate
Published 4 October 2023 Science ClosedTags: algae, biological response, growth, laboratory, light, multiple factors, primary production, South Pacific
Highlights
- Microalgae growth is governed by CO2 input and light intensity.
- CO2 input & light intensity have an opposing impact on the culture pH.
- Microalgae growth can be inhibited by excessive lighting or CO2 input.
- Balancing CO2 input and light intensity is essential for CO2 fixation by microalgae.
- CO2 fixation rate of 4.2 g/L by Scenedesmus sp. at optimised condition.
Abstract
The interplay between CO2 input and light intensity is investigated to provide new insight to optimise microalgae growth rate in photobioreactors for environmental remediation, carbon capture, and biomass production. Little is known about the combined effect of carbon metabolism and light intensity on microalgae growth. In this study, carbonated water was transferred to the microalgae culture at different rates and under different light intensities for observing the carbon composition and growth rate. Results from this study reveal opposing effects from CO2 input and light intensity on the culture solution pH and ultimately microalgae growth rate. Excessive CO2 concentration can inhibit microalgae growth due to acidification caused by CO2 dissolution. While increasing light intensity can increase pH because the carboxylation process consumes photons and transfers hydrogen ions into the cell. This reaction is catalysed by the enzyme RuBisCO, which functions optimally within a specific pH range. By balancing CO2 input and light intensity, high microalgae growth rate and carbon capture could be achieved. Under the intermittent CO2 transfer mode, at the optimal condition of 850 mg/L CO2 input and 1089 μmol/m2/s light intensity, leading to the highest microalgae growth rate and carbon fixation of 4.2 g/L as observed in this study.
Continue reading ‘Role of culture solution pH in balancing CO2 input and light intensity for maximising microalgae growth rate’Decreased calcification to photosynthesis ratio in coccolithophores under reduced O2 and elevated CO2 environment
Published 2 October 2023 Science ClosedTags: biological response, calcification, growth, laboratory, multiple factors, oxygen, photosynthesis, phytoplankton, primary production
We examined the physiological performance in the most cosmopolitan coccolithophorid, Emiliania huxleyi, and Gephyrocapsa oceanica, which were treated with 8.3 (AO), 4.6 (MO) and 2.5 (LO) mg L–1 O2 under 400 (AC) and1000 (HC) ppm CO2 conditions. Elevated CO2 decreased the specific growth rate of cells cultured under AO and LO conditions in both species, but it increased the rate in the MO-grown E. huxleyi. Regardless of the CO2 levels, diminished O2 concentration inhibited the growth rate in E. huxleyi while accelerating the rate in G. oceanica. LO reduced the particulate organic carbon (POC) production rate compared to the AO treatment in both species. Additionally, the decrease was higher in the HC cultures than in the AC ones. LO also inhibited the production rate of particulate inorganic carbon (PIC) compared to the AO/AC treatment. Due to a higher reduction in the production rate of PIC than POC, the PIC/POC ratio was decreased in the LO treatment compared to the AO/AC treatment. The current study reveals that low O2 can, individually or in combination with high CO2, considerably affect the physiology of marine photoautotrophic organisms.
Continue reading ‘Decreased calcification to photosynthesis ratio in coccolithophores under reduced O2 and elevated CO2 environment’Hidden impacts of climate change on biological responses of marine life
Published 28 September 2023 Science ClosedTags: biological response, calcification, community composition, growth, morphology, mortality, otherprocess, performance, physiology, reproduction, review
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’Impacts of ocean acidification on physiology and ecology of marine invertebrates: a comprehensive review
Published 26 September 2023 Science ClosedTags: 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’Influence of seagrass on juvenile Pacific oyster growth in two US west coast estuaries with different environmental gradients
Published 25 September 2023 Science ClosedTags: 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’Early life physiological and energetic responses of Atlantic silversides (Menidia menidia) toocean acidification, warming, and hypoxia
Published 22 September 2023 Science ClosedTags: 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’
