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 'review'
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
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’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’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’Physiological and ecological tipping points caused by ocean acidification
Published 7 September 2023 Science ClosedTags: biological response, calcification, photosynthesis, physiology, review
Ocean acidification is predicted to cause profound shifts in many marine ecosystems by impairing the ability of calcareous taxa to calcify and grow, and by influencing the photo-physiology of many others. In both calcifying and non-calcifying taxa, ocean acidification could further impair the ability of marine life to regulate internal pH, and thus metabolic function and/or behaviour. Identifying tipping points at which these effects will occur for different taxa due to the direct impacts of ocean acidification on organism physiology is difficult and they have not adequately been determined for most taxa, nor for ecosystems at higher levels. This is due to the presence of both resistant and sensitive species within most taxa. However, calcifying taxa such as coralline algae, corals, molluscs, and sea urchins appear to be most sensitive to ocean acidification. Conversely, non-calcareous seaweeds, seagrasses, diatoms, cephalopods, and fish tend to be more resistant, or even benefit from the direct effects of ocean acidification. While physiological tipping points of the effects of ocean acidification either do not exist or are not well defined, their direct effects on organism physiology will have flow on indirect effects. These indirect effects will cause ecologically tipping points in the future through changes in competition, herbivory and predation. Evidence for indirect effects and ecological change is mostly taken from benthic ecosystems in warm temperate–tropical locations in situ that have elevated CO2. Species abundances at these locations indicate a shift away from calcifying taxa and towards non-calcareous at high CO2 concentrations. For example, lower abundance of corals and coralline algae, and higher covers of non-calcareous macroalgae, often turfing species, at elevated CO2. However, there are some locations where only minor changes, or no detectable change occurs. Where ecological tipping points do occur, it is usually at locations with naturally elevated pCO2 concentrations of 500 μatm or more, which also corresponds to just under that concentrations where the direct physiological impacts of ocean acidification are detectable on the most sensitive taxa in laboratory research (coralline algae and corals). Collectively, the available data support the concern that ocean acidification will most likely cause ecological change in the near future in most benthic marine ecosystems, with tipping points in some ecosystems at as low as 500 μatm pCO2. However, much more further research is required to more adequately quantify and model the extent of these impacts in order to accurately project future marine ecosystem tipping points under ocean acidification.
Continue reading ‘Physiological and ecological tipping points caused by ocean acidification’Seasonal variability of the surface ocean carbon cycle: a synthesis
Published 4 September 2023 Science ClosedTags: chemistry, globalmodeling, modeling, review
Abstract
The seasonal cycle is the dominant mode of variability in the air-sea CO2 flux in most regions of the global ocean, yet discrepancies between different seasonality estimates are rather large. As part of the Regional Carbon Cycle Assessment and Processes phase 2 project (RECCAP2), we synthesize surface ocean pCO2 and air-sea CO2 flux seasonality from models and observation-based estimates, focusing on both a present-day climatology and decadal changes between the 1980s and 2010s. Four main findings emerge: First, global ocean biogeochemistry models (GOBMs) and observation-based estimates (pCO2 products) of surface pCO2 seasonality disagree in amplitude and phase, primarily due to discrepancies in the seasonal variability in surface DIC. Second, the seasonal cycle in pCO2 has increased in amplitude over the last three decades in both pCO2 products and GOBMs. Third, decadal increases in pCO2 seasonal cycle amplitudes in subtropical biomes for both pCO2 products and GOBMs are driven by increasing DIC concentrations stemming from the uptake of anthropogenic CO2 (Cant). In subpolar and Southern Ocean biomes, however, the seasonality change for GOBMs is dominated by Cant invasion, whereas for pCO2 products an indeterminate combination of Cant invasion and climate change modulates the changes. Fourth, biome-aggregated decadal changes in the amplitude of pCO2 seasonal variability are largely detectable against both mapping uncertainty (reducible) and natural variability uncertainty (irreducible), but not at the gridpoint scale over much of the northern subpolar oceans and over the Southern Ocean, underscoring the importance of sustained high-quality seasonally-resolved measurements over these regions.
Key Points
- pCO2 seasonal cycle amplitude changes over 1985-2018 are detectable against both mapping uncertainty and natural variability uncertainty
- The dominant driver of pCO2 amplitude increases over decadal timescales is attributed to the direct effect of Cant invasion
- A discrepancy is found with surface DIC seasonality being systematically less in GOBMs than in surface DIC observation-based products
Chapter 12 – Climate change and multiple stressors
Published 25 August 2023 Science ClosedTags: biological response, crustaceans, review
In this review we assess and predict the impacts of climate change on the ecophysiology and distribution of Carcinus maenas—the green or five-spine shore crab—based on research to date on this and other marine invertebrates. Warming is expected to minimally affect C. maenas because of its broad thermal tolerances, planktotrophic development, and capacity for rapid adaptation; however, the embryos and larvae are more sensitive to environmental drivers, so the species may be more restricted than expected by adults alone. The impacts of ocean acidification are mostly expected to be minimal, as for other crustaceans. The osmoregulatory capacity of the euryhaline Carcinus genus means it is already adapted to fluctuating salinities. Furthermore, in many cases the effect of combining environmental drivers seems to minimize their joint impacts on C. maenas. Strong currents and upwelling may enhance recruitment but have less predictable effects. Finally, we echo predictions of further poleward range expansion of C. maenas as the climate warms. We conclude that C. maenas is well positioned to face minimum impacts from global change.
Continue reading ‘Chapter 12 – Climate change and multiple stressors’Rising snow line: Ocean acidification and the submergence of seafloor geomorphic features beneath a rising carbonate compensation depth
Published 22 August 2023 Science ClosedTags: Antarctic, Arctic, chemistry, Indian, modeling, North Atlantic, North Pacific, regionalmodeling, review, South Atlantic, South Pacific
Highlights
- Ocean acidification has caused the carbonate compensation depth (CCD) to rise by ~98 m.
- Seafloor area below the CCD has increased by 3.6% in the last 200 years.
- Risk of impact of rising CCD is greatest in the western equatorial Atlantic Ocean.
- Different geomorphic features impacted by rising CCD in different ocean areas.
Abstract
Due to burning of fossil fuels, carbon dioxide is being absorbed by the ocean where its chemical conversion to carbonic acid has already caused the surface ocean to become more acidic than it has been for at least the last 2 million years. Global ocean modeling suggests that the carbonate compensation depth (CCD) has already risen by nearly 100 m on average since pre-industrial times and will likely rise further by several hundred meters more this century. Potentially millions of square kilometres of ocean floor will undergo a rapid transition in terms of the overlying water chemistry whereby calcareous sediment will become unstable causing the carbonate “snow line” to rise.We carried out a spatial analysis of seafloor geomorphology to assess the area newly submerged below the rising CCD. We found that shoaling of the CCD since the industrial revolution has submerged 12,432,096 km2 of ocean floor (3.60% of total ocean area) below the CCD. Further hypothetical shoaling of the CCD by 100 m increments illustrated that the surface area of seafloor submerged below the CCD has risen by 14% with 300 m of shoaling, such that 51% of the ocean area will be below the CCD. All categories of geomorphic feature mapped in one global database intersect the lysocline and will be (or already are) submerged below the CCD with much regional variation since the rise in CCD depth during the last 150 years varies significantly between different ocean regions. For seamounts, the highest percentages of increase in area submerged below the CCD occurred in the Southern Indian Ocean and the South West Atlantic regions (6.3% and 5.9%, respectively). For submarine canyons we found the South West Atlantic increased from 3.9% in pre-industrial times to 8.0% at the present time, the highest percentage of canyons found below the CCD in any ocean region.We also carried out a relative risk assessment for future submergence of ocean floor below the CCD in 17 ocean regions. In our assessment we assumed that the change in CCD from pre-industrial times to the present is an indicator of the likelihood and the change in percentage of seafloor submerged below the CCD due to a hypothetical 300 m rise in the CCD is an indicator of the consequences. We found that the western equatorial Atlantic is at high risk and 9 other Ocean Regions are at moderate risk. Overall, geomorphic features in the Atlantic Ocean and southern Indian Ocean are at greater risk of impact from a rising CCD than Pacific and other Indian Ocean regions.A separate analysis of the Arctic Ocean points to the possible submergence of glacial troughs incised on the continental shelf within a mid-depth (400–800 m) acidified water mass. We also found that the area of national Exclusive Economic Zones submerged below the rising CCD exhibits extreme variability; with 300 m of CCD shoaling we found a > 12% increase in area submerged below the CCD for 23 national EEZs, whereas there was virtually no change for other countries.
Continue reading ‘Rising snow line: Ocean acidification and the submergence of seafloor geomorphic features beneath a rising carbonate compensation depth’Ocean acidification: positive and negative impacts on seaweeds
Published 21 August 2023 Science ClosedTags: algae, biological response, review
Due to industrial revolution and anthropogenic activities carbon-di-oxide (CO2 ) in the atmosphere has increased day by day. Deforestation, burning of fossil fuels, forest fires resulting in the enhancement of CO2 in the ocean ecosystem. About 30% of the atmospheric CO2 is absorbed by the ocean surface water which results in carbonic acids. The carbonic acids formed cause harmful effects to marine aquatic lives including sea animals and seaweeds. A series of chemical reactions results in the formation of carbonic acids and bicarbonates which has a bad impact on the living creatures. Marine organisms, especially hard shell containing species like corals and oysters become more effective as their skeleton is formed by the dissolved carbonate and calcium. On the other hand, clownfish have decreased in the additional acidic waters than normal marine water. Around 14-17 billion years ago, at the age of the middle Miocene, the pH of the ocean was less than 8 which resembles the present day environment (https://www.noaa.gov/education/resource-collections/ocean-coasts/ocean-acidification).
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Continue reading ‘Ocean acidification: positive and negative impacts on seaweeds’Using meta-analysis to explore the roles of global upwelling exposure and experimental design in bivalve responses to low pH
Published 16 August 2023 Science ClosedTags: biological response, individualmodeling, modeling, mollusks, physiology, respiration, review
Highlights
- Meta-analysis was used to assess bivalve responses to low pH.
- Strong upwelling regions may yield bivalves that are less sensitive to low pH.
- Upwelling explains up to 49 % variability of bivalve metabolic responses to low pH.
- Larger carbonate chemistry deltas in experiments yield stronger responses.
Abstract
Low pH conditions, associated with ocean acidification, represent threats to many commercially and ecologically important organisms, including bivalves. However, there are knowledge gaps regarding factors explaining observed differences in biological responses to low pH in laboratory experiments. Specific sources of local adaptation such as upwelling exposure and the role of experimental design, such as carbonate chemistry parameter changes, should be considered. Linking upwelling exposure, as an individual oceanographic phenomenon, to responses measured in laboratory experiments may further our understanding of local adaptation to global change. Here, meta-analysis is used to test the hypotheses that upwelling exposure and experimental design affect outcomes of individual, laboratory-based studies that assess bivalve metabolic (clearance and respiration rate) responses to low pH. Results show that while bivalves generally decrease metabolic activity in response to low pH, upwelling exposure and experimental design can significantly impact outcomes. Bivalves from downwelling or weak upwelling areas decrease metabolic activity in response to low pH, but bivalves from strong upwelling areas increase or do not change metabolic activity in response to low pH. Furthermore, experimental temperature, exposure time and magnitude of the change in carbonate chemistry parameters all significantly affect outcomes. These results suggest that bivalves from strong upwelling areas may be less sensitive to low pH. This furthers our understanding of local adaptation to global change by demonstrating that upwelling alone can explain up to 49 % of the variability associated with bivalve metabolic responses to low pH. Furthermore, when interpreting outcomes of individual, laboratory experiments, scientists should be aware that higher temperatures, shorter exposure times and larger changes in carbonate chemistry parameters may increase the chance of suppressed metabolic activity.
Continue reading ‘Using meta-analysis to explore the roles of global upwelling exposure and experimental design in bivalve responses to low pH’The effects of climate change on the ecology of fishes
Published 14 August 2023 Science ClosedTags: biological response, fish, review
Ocean warming and acidification are set to reshuffle life on Earth and alter ecological processes that underpin the biodiversity, health, productivity, and resilience of ecosystems. Fishes contribute significantly to marine, estuarine, and freshwater species diversity and the functioning of marine ecosystems, and are not immune to climate change impacts. Whilst considerable effort has been placed on studying the effects of climate change on fishes, much emphasis has been placed on their (eco)physiology and at the organismal level. Fishes are affected by climate change through impacts at various levels of biological organisation and through a large variety of traits, making it difficult to make generalisations regarding fish responses to climate change. Here, we briefly review the current state of knowledge of climate change effects on fishes across a wide range of subfields of fish ecology and evaluate these effects at various scales of biological organisation (from genes to ecosystems). We argue that a more holistic synthesis of the various interconnected subfields of fish ecology and integration of responses at different levels of biological organisation are needed for a better understanding of how fishes and their populations and communities might respond or adapt to the multi-stressor effects of climate change. We postulate that studies using natural analogues of climate change, meta-analyses, advanced integrative modelling approaches, and lessons learned from past extreme climate events could help reveal some general patterns of climate change impacts on fishes that are valuable for management and conservation approaches. Whilst these might not reveal many of the underlying mechanisms responsible for observed biodiversity and community change, their insights are useful to help create better climate adaptation strategies for their preservation in a rapidly changing ocean.
Continue reading ‘The effects of climate change on the ecology of fishes’Estuarine shellfish and climate change
Published 14 August 2023 Science ClosedTags: biological response, crustaceans, echinoderms, mollusks, review
Over centuries, shellfish populations have directly and indirectly benefitted humans living in coastal communities by providing fisheries and ecosystem services. The naturally dynamic estuarine environment, home to many economically important shellfish populations is, however, also commonly subjected to anthropogenic pressure from exploitation, pollution, and the acceleration of climate change. Climate change alters the rate and direction of long-term biogeochemical change in the ocean, but also, in combination with large-scale climate oscillations and other factors, can modulate the frequency, persistence, and/or magnitude of extreme coastal events including estuarine heatwaves, coastal hypoxia, and coastal acidification. This chapter explores the dynamic variability of the estuarine environment and assesses the impacts of climate stressors in isolation and in combination with other climatic/anthropogenic stressors on estuarine shellfish species. Individually, warming temperatures can alter the rates of physiological processes and can result in changes in growth and reproduction, while extremes in temperature can elicit physiological stress, mortality, or even local extinctions. Range contractions or expansions resulting from shifts in temperature or salinity can have cascading effects on ecosystem functioning, as important functional roles associated with shellfish (i.e., suspension-feeding, habitat engineering, bioturbation, predation) are gained or lost. Since nearly all shellfish species produce calcified structures exposed to the external environment, increasing CO2 concentrations and extremes in CO2 can have negative consequences on calcification that may vary by life stage and may have fitness-related consequences. Low oxygen extremes, which may become more persistent or severe under warming temperatures, consistently yield negative effects on the growth, development, metabolism, reproduction, survival, and/or abundance of mollusks and crustaceans and, thus, can have disproportionate impacts on ecosystem functioning.Estuaries commonly host co-occurring extremes (e.g., hypoxia and acidification), forcing organisms to cope with multiple stressors. Multi-stressors, an emerging field of research, can have a range of additive, synergistic, and antagonistic effects on shellfish species, with additional stressors typically yielding more negative outcomes than single stressors. Still, there are many unknowns regarding the potential effects of climate change syndromes on coastal shellfish, particularly in dynamic estuarine environments, and examinations of the combined impacts of warming/hypoxia/acidification and/or harmful algal blooms have only just begun. Autonomous observing platforms and high-frequency sensor arrays are essential to generating long-term and fine-scale time series datasets to characterize the shifting biogeochemical patterns under climate change. It will also be critical to scale up physiological studies to assess impacts on populations, communities, and ecosystems. Finally, to protect and/or restore shellfish resources, continued collaboration between communities and researchers on adaptive strategies that mitigate harm to shellfish populations experiencing extremes in future change will be vital.
Continue reading ‘Estuarine shellfish and climate change’Estuarine acidification under a changing climate
Published 11 August 2023 Science ClosedTags: biogeochemistry, chemistry, North Atlantic, review
The increase of anthropogenic carbon dioxide (CO2) has decreased seawater pH and carbonate mineral saturation state, a process known as ocean acidification (OA), which threatens the health of organisms and ecosystems. In estuaries and coastal hypoxic waters, anthropogenic CO2-induced acidification is enhanced by intense respiration and weak acid–base buffer capacity. Here I provide a succinct review of our state of knowledge of drivers for and biogeochemical impacts on estuarine acidification. I will review how river–ocean mixing, air–water gas exchange, biological production–respiration, anaerobic respiration, calcium carbonate (CaCO3) dissolution, and benthic inputs influence aquatic acid–base properties in estuarine waters. I will emphasize the spatial and temporal dynamics of partial pressure of CO2 (pCO2), pH, and calcium carbonate mineral saturation states (Ω), with examples from the Chesapeake Bay, the Mississippi River plume and hypoxic zone, and other estuaries to illustrate how natural and anthropogenic processes may lead to estuarine and coastal acidification.
Continue reading ‘Estuarine acidification under a changing climate’Responses of marine macroalgae to climate change drivers
Published 11 August 2023 Science ClosedTags: biological response, crustaceans, echinoderms, mollusks, review
Climate changes are progressively altering global ocean environments, leading to ocean acidification and warming, marine heatwaves, deoxygenation, and enhanced exposure of UV radiations within upper mixing layers. Marine macroalgae are affected by these environmental changes in coastal waters, where changing magnitudes of these drivers are usually larger than in open oceans. While macroalgae have developed physiological mechanisms to cope with these stressors, their responses to or tolerances to these stressors are species-specific and spatiotemporally variable. Fleshy macroalgal species are commonly capable of tolerating moderate decline of pH and diel fluctuations of pH, and their growth and photosynthesis can be enhanced by elevated CO2 concentrations in seawater and in the air during emersion at low tides. However, macroalgal calcifiers are especially sensitive to ocean acidification, with their calcification being reduced, which exacerbates the harm of solar UV radiation due to thinned protective calcareous layers. Marine warming and heatwaves, however, may endanger most macroalgal species as their seasonality of life cycle is temperature-dependent. Macroalgae either distributed in upper or lower intertidal zones are susceptible to UV radiation, which may have negative, neutral, or beneficial effects on them, depending on the levels of UV and other factors. UV-A (315–400 nm) can stimulate the photosynthesis of macroalgae under low to moderate levels of solar radiation; however, UV-B (280–315 nm) mainly causes negative effects. While the combined effects of elevated temperature, CO2, and UV radiation have rarely been documented, exposures to marine heatwaves and high levels of UV can be fatal to microscopic stages of macroalgae. Apart from the species found in estuaries, the physiology and community structure of macroalgae can be influenced by reduced salinity and pH associated with rainfall and/or terrestrial runoffs. Nevertheless, reduced O2 availability associated with ocean deoxygenation and/or hypoxia, promoted by eutrophication and ocean warming, may favor macroalgal carbon fixation because of suppressed photorespiration due to reduced O2 vs. CO2 ratios, although little documentation exists to support this possibility. While macroscopic stages of macroalgae are resilient or even benefit from some of the drivers, their microscopic stages and/or juveniles are susceptible to ocean climate changes, and the sustainability of their life cycles is endangered. In this chapter, we review and analyze the responses of different macroalgal groups and different life cycle stages to climate change drivers individually and/or jointly based on the literature surveyed, along with perspectives for future studies on the multifaceted effects of ocean climate changes.
Continue reading ‘Responses of marine macroalgae to climate change drivers’Variable exposure to multiple climate stressors across the California marine protected area network and policy implications
Published 3 August 2023 Science ClosedTags: chemistry, field, North Pacific, policy, review
The efficacy of marine protected areas (MPAs) may be reduced when climate change disrupts the ecosystems and human communities around which they are designed. The effects of ocean warming on MPA functioning have received attention but less is known about how multiple climatic stressors may influence MPAs efficacy. Using a novel dataset incorporating 8.8 million oceanographic observations, we assess exposure to potentially stressful temperatures, dissolved oxygen concentrations, and pH levels across the California MPA network. This dataset covers more than two-thirds of California’s 124 MPAs and multiple biogeographic domains. However, spatial-temporal and methodological patchiness constrains the extent to which systematic evaluation of exposure is possible across the network. Across a set of nine well-monitored MPAs, the most frequently observed combination of stressful conditions was hypoxic conditions (<140 umol/kg) co-occurring with low pH (<7.75). Conversely, MPAs exposed most frequently to anomalously warm conditions were less likely to experience hypoxia and low pH, although exposure to hypoxia varied throughout the 2014–2016 marine heatwaves. Finally, we found that the spatial patterns of exposure to hypoxia and low pH across the MPA network remained stable across years. This multiple stressor analysis both confirms and challenges prior hypotheses regarding MPA efficacy under global environmental change.
Continue reading ‘Variable exposure to multiple climate stressors across the California marine protected area network and policy implications’Contaminants disrupt aquatic food webs via decreased consumer efficiency
Published 27 July 2023 Science ClosedTags: biological response, performance, review
Highlights
- Overall, contaminants reduce consumption rates across aquatic ecosystems.
- Contaminants disproportionately impact consumers relative to resource taxa.
- Contaminants have greater negative effects on primary consumers with sedentary resources.
- Metal contaminants have relatively strong dampening effects on consumption.
- 33 % of studies expose contaminants to only consumer or resource, not both.
Abstract
Changes in consumer-resource dynamics due to environmental stressors can alter energy flows or key interactions within food webs, with potential for cascading effects at population, community, and ecosystem levels. We conducted a meta-analysis to quantify the direction and magnitude of changes in consumption rates following exposure of consumer-resource pairs within freshwater-brackish and marine systems to anthropogenic CO2, heavy metals, microplastics, oil, pesticides, or pharmaceuticals. Across all contaminants, exposure generally decreased consumption rates, likely due to reduced consumer mobility or search efficiency. These negative effects on consumers appeared to outweigh co-occurring reductions in prey vigilance or antipredator behaviors following contaminant exposure. Consumption was particularly dampened in freshwater-brackish systems, for consumers with sedentary prey, and for lower-trophic-level consumers. This synthesis indicates that energy flow up the food web, toward larger – often ecologically and economically prized – taxa may be dampened as aquatic contaminant loads increase.
Continue reading ‘Contaminants disrupt aquatic food webs via decreased consumer efficiency’Canada’s marine carbon sink: an early career perspective on the state of research and existing knowledge gaps
Published 26 July 2023 Science ClosedTags: Arctic, biogeochemistry, North Atlantic, North Pacific, review
Improving our understanding of how the ocean absorbs carbon dioxide is critical to climate change mitigation efforts. We, a group of early career ocean professionals working in Canada, summarize current research and identify steps forward to improve our understanding of the marine carbon sink in Canadian national and offshore waters. We have compiled an extensive collection of reported surface ocean air–sea carbon dioxide exchange values within each of Canada’s three adjacent ocean basins. We review the current understanding of air–sea carbon fluxes and identify major challenges limiting our understanding in the Pacific, the Arctic, and the Atlantic Ocean. We focus on ways of reducing uncertainty to inform Canada’s carbon stocktake, establish baselines for marine carbon dioxide removal projects, and support efforts to mitigate and adapt to ocean acidification. Future directions recommended by this group include investing in maturing and building capacity in the use of marine carbon sensors, improving ocean biogeochemical models fit-for-purpose in regional and ocean carbon dioxide removal applications, creating transparent and robust monitoring, verification, and reporting protocols for marine carbon dioxide removal, tailoring community-specific approaches to co-generate knowledge with First Nations, and advancing training opportunities for early career ocean professionals in marine carbon science and technology.
Continue reading ‘Canada’s marine carbon sink: an early career perspective on the state of research and existing knowledge gaps’Climate-change impacts on cephalopods: a meta-analysis
Published 25 July 2023 Science ClosedTags: biological response, mollusks, review
Aside from being one of the most fascinating groups of marine organisms, cephalopods play a major role in marine food webs, both as predators and as prey, while representing key living economic assets, namely for artisanal and subsistence fisheries worldwide. Recent research suggests that cephalopods are benefitting from ongoing environmental changes and the overfishing of certain fish stocks (i.e., of their predators and/or competitors), putting forward the hypothesis that this group may be one of the few ‘winners’ of climate change. While many meta-analyses have demonstrated negative and overwhelming consequences of ocean warming (OW), acidification (OA), and their combination (OWA) for a variety of marine taxa, such a comprehensive analysis is lacking for cephalopod molluscs. In this context, the existing literature was surveyed for peer-reviewed articles featuring the sustained (≥24h) and controlled exposure of cephalopod species (Cephalopoda Class) to these factors, applying a comparative framework of mixed-model meta-analyses (784 control-treatment comparisons, from 47 suitable articles). Impacts on a wide set of biological categories at the individual level (e.g., survival, metabolism, behaviour, cell stress, growth) were evaluated and contrasted across different ecological attributes (i.e., taxonomic lineages, climates, and ontogenetic stages). Contrary to what is commonly assumed, OW arises as a clear threat to cephalopods, while OA exhibited more restricted impacts. In fact, OW impacts were ubiquitous across different stages of ontogeny, taxonomical lineages (i.e., octopuses, squids, and cuttlefishes). These results challenge the assumption that cephalopods benefit from novel ocean conditions, revealing an overarching negative impact of OW in this group. Importantly, we also identify lingering literature gaps, showing that most studies to date focus on OW and early life stages of mainly temperate species. Our results raise the need to consolidate experimental efforts in a wider variety of taxa, climate regions, life stages, and other key environmental stressors such as deoxygenation and hypoxia, to better understand how cephalopods will cope with future climate change.
Continue reading ‘Climate-change impacts on cephalopods: a meta-analysis ‘Surviving in an acidifying ocean: acid-base physiology and energetics of the sea urchin larva
Published 13 July 2023 Science ClosedTags: biological response, echinoderms, physiology, review
The sea urchin larva has been used by biologists for more than a century to study the development and evolution of animals. Surprisingly, very little information has been generated regarding the physiology of this small planktonic organism. However, in the context of anthropogenic CO2-driven ocean acidification (OA), the membrane transport physiology and energetics of this marine model organism have received considerable attention in the past decade. This has led to the discovery of new, exciting physiological systems, including a highly alkaline digestive tract and the calcifying primary mesenchyme cells that generate the larval skeleton. These physiological systems directly relate to the energetics of the organisms when challenged by OA. Here we review the latest membrane transport physiology and energetics in the sea urchin larva, we identify emerging questions, and we point to important future directions in the field of marine physiology in times of rapid climate change.
Continue reading ‘Surviving in an acidifying ocean: acid-base physiology and energetics of the sea urchin larva’The potential role of Posidonia oceanica for mitigating acidification on coastal waters of Europe
Published 12 July 2023 Science ClosedTags: biogeochemistry, biological response, chemistry, field, Mediterranean, mitigation, phanerogams, review
Ocean acidification is a major environmental concern that has significant ecological., economic, and social implications. The plantation and restoration of seagrass meadows in coastal waters, specifically Posidonia oceanica, is one possible method to combat ocean acidification and has the potential to have a significant positive impact on the marine environment and the overall state of the biosphere. As there has been a decline of Posidonia oceanica of about 30% in the Mediterranean Sea over the past three decades to about 1.2 mio ha in the Mediterranean Sea, the positive effects of the sea grass have diminished due to anthropogenic influence. Still, its importance as a carbon sink should not be underestimated. By using recent literature and different studies that have been analysed of the capacity of sea grass to mitigate the impacts of ocean acidification and the effects on the marine ecosystems, supported by several experiments that have been conducted, this thesis demonstrated the importance of Posidonia oceanica. The experiments showed that seagrass ecosystems have higher pH than ecosystems without seagrass, with a mean difference of 0.43. As the pH is interlocked with the CO2-levels and the oxygen levels, also experiments on these factors have been conducted. In general, the concentration of oxygen with P. oceanica present is 2mg/L higher than without. Equally, the CO2 concentration was lower with P. oceanica present. The Posidonia oceanica meadows present in the Mediterranean Sea are able to fixate about 13,3 mio tons of CO2, which is equal to 0,3% of Europeans CO2 emissions. About 2,8 mio tons of CO2 are sequestered by the sea grass, which is about 0,07% of European CO2 emissions. Furthermore, recent plantation efforts show the successful restoration of seagrass meadows and their overall benefits for the regional environment. Overall, this paper provides valuable insights into the potential role of seagrass meadows in mitigating ocean acidification and improving marine biosystems while providing specific numbers to support its findings.
Continue reading ‘The potential role of Posidonia oceanica for mitigating acidification on coastal waters of Europe’
