Greenhouse gas emissions from land-use change, fossil fuel, agriculture, transportation, and electricity sectors expose marine ecosystems to overlapping environmental stressors. Existing climate vulnerability assessment methods analyze the frequency of extreme conditions but often minimally consider how environmental data gaps hinder assessments. Here, we show an approach that assesses vulnerability and the uncertainty introduced by monitoring data gaps, using a case study of ocean acidification and deoxygenation in coastal California. We employ 5 million publicly available oceanographic observations and existing studies on species responses to low pH, low oxygen conditions to calculate vulnerability for six ecologically and economically valuable benthic invertebrate species: red sea urchin (Mesocentrotus franciscanus), purple sea urchin (Strongylocentrotus purpurpatus), warty sea cucumber (Apostichopus parvimensis), pink shrimp (Pandalus jordani), California spiny lobster (Panulirus interruptus), and Dungeness crab (Metacarncinus magister). Further, we evaluate the efficacy of current monitoring programs by examining how data gaps heighten associated uncertainty. We find that most organisms experience low oxygen (<35% saturation) conditions less frequently than low pH ( < 7.6) conditions. It is only deeper dwelling (>75 m depth) life stages such as Dungeness crab adults and pink shrimp embryos, juveniles, and adults that experience more frequent exposure to low oxygen conditions. Adult Dungeness crabs experience the strongest seasonal variation in exposure. Though these trends are intriguing, exposure remains low for most species despite well-documented pH and oxygen declines and strengthening upwelling in the central portions of the California Current. Seasonal biases of data collection and sparse observations near the benthos and at depths where organisms most frequently experience stressful conditions undermine exposure estimates. Herein we provide concrete examples of how pink shrimp and Dungeness crab fisheries may be impacted by our findings, and provide suggestions for incorporating oceanographic data into management plans. By limiting our scope to California waters and assessing the limitations presented by current monitoring coverage, this study aims to provide a granular, actionable framework that policymakers and managers can build from to prioritize targeted enhancements and sustained funding of oceanographic monitoring recommendations.
Continue reading ‘Assessing benthic invertebrate vulnerability to ocean acidification and de-oxygenation in California: the importance of effective oceanographic monitoring networks’Posts Tagged 'oxygen'
Assessing benthic invertebrate vulnerability to ocean acidification and de-oxygenation in California: the importance of effective oceanographic monitoring networks
Published 21 February 2025 Science ClosedTags: biological response, chemistry, crustaceans, echinoderms, fisheries, methods, multiple factors, oxygen, policy, review
The combined effects of ocean acidification and hypoxia, part 1
Published 5 February 2025 Presentations , Resources ClosedTags: chemistry, mitigation, multiple factors, oxygen
Dr. Richard Feely (NOAA/PMEL) presents on “The Combined Effects of Ocean Acidification and Hypoxia” (Part 1) with Dr. Nina Bednarsek (Oregon State University) at our December 5th, 2024 Partnerships for Tribal Carbon Solutions workshop: Can Rocks Fix the Climate and Heal the Sea? Richard Feely from NOAA’s Pacific Marine Environmental Laboratory discusses ocean acidification in the Pacific Northwest, one of the most vulnerable regions globally. He explains how rising atmospheric CO₂ leads to ocean acidification through chemical reactions that increase hydrogen ion concentration, lowering pH and reducing carbonate availability, which threatens calcifying marine organisms. He highlights how coastal upwelling and biological respiration amplify acidification, making subsurface waters particularly susceptible. Using models and observational data, he demonstrates that acidification is progressing rapidly, with pH declines exceeding EPA water quality criteria in some areas. He emphasizes that adding ocean alkalinity could counteract these changes, offering a potential strategy to mitigate acidification’s impacts.
Global Ocean Health, 29 January 2025. Video.
Investigating the effects of environmental stress on coastal zooplankton populations: from mechanistic drivers to trophic impacts
Published 29 January 2025 Science ClosedTags: abundance, biological response, BRcommunity, crustaceans, field, laboratory, mortality, multiple factors, otherprocess, oxygen, performance, zooplankton
Environmental stressors, such as hypoxia and acidification, are increasing in intensity, duration, and extent in coastal waters and estuaries. Environmental stressors are known to affect a wide range of marine species, including zooplankton. Zooplankton are a critical link in marine food webs, connecting phytoplankton to higher trophic levels such as economically important fish, and are thought to be informative indicators of ecosystem change. For this reason, increased attention has been paid to understanding the mechanisms shaping zooplankton populations. Previous studies have shown that zooplankton exhibit both lethal and sublethal responses to changes in dissolved oxygen and pH. However, there is a range of species-specific responses to stressors. Different responses across species alter zooplankton community composition and spatial distributions, directly impacting predator-prey interactions and the trophic dynamics in coastal environments. This dissertation integrates laboratory experiments, in situ observations, and field work to understand how environmental stressors affect coastal zooplankton populations and nearshore food webs. In Chapter 1, I conducted laboratory experiments to investigate whether the copepod, Calanus pacificus, showed behavioral responses to stressors, and whether these responses lead to changes in vertical population distributions. Our laboratory experiments demonstrated significant effects of bottom water hypoxia and acidification on behavioral avoidance, swimming statistics, and apparent mortality rates in C. pacificus. In Chapter 2, I used a remote camera system to quantify in situ behavioral responses of zooplankton to stressors, using results from Chapter 1 to generate hypotheses about observations in the field. Our in situ videos revealed that copepods in stressful conditions exhibited significantly slower swimming speeds than copepods in non-stressful conditions, while amphipods showed significantly decreased abundances within stressful conditions. Finally, in Chapter 3, I collected zooplankton net tows in an intertidal estuary to investigate the transport of pelagic species into eelgrass beds and the role of eelgrass beds as potential sinks of pelagic zooplankton over the tidal cycle, potentially due to predation by juvenile fish. We found evidence of transport of pelagic species into intertidal habitats and measured large spatial and temporal variability, highlighting the need for sampling programs that can capture small-scale variability. This dissertation provides insight into the mechanisms that link the effects of environmental stressors across individual responses to population, community, and ecosystem level scales and suggests novel methodologies to help advance our understanding of changing zooplankton dynamics.
Continue reading ‘Investigating the effects of environmental stress on coastal zooplankton populations: from mechanistic drivers to trophic impacts’Single-larva RNA sequencing reveals that red sea urchin larvae are vulnerable to co-occurring ocean acidification and hypoxia
Published 22 January 2025 Science ClosedTags: biological response, dissolution, echinoderms, fisheries, molecular biology, multiple factors, North Pacific, oxygen, physiology, reproduction
Anthropogenic carbon dioxide emissions have been increasing rapidly in recent years, driving pH and oxygen levels to record low concentrations in the oceans. Eastern boundary upwelling systems such as the California Current System (CCS) experience exacerbated ocean acidification and hypoxia (OAH) due to the physical and chemical properties of the transported deeper waters. Research efforts have significantly increased in recent years to investigate the deleterious effects of climate change on marine species, but have not focused on the impacts of simultaneous OAH stressor exposure. Additionally, few studies have explored the physiological impacts of these environmental stressors on the earliest life stages, which are more vulnerable and represent natural population bottlenecks in organismal life cycles. The physiological response of the ecologically and commercially important red sea urchin (Mesocentrotus franciscanus) was assessed by exposing larvae to a variety of OAH conditions, mimicking the range of ecologically relevant conditions encountered currently and in the near future along the CCS. Skeleton dissolution, larval development, and gene expression show a response with clearly delineated thresholds that were related to OAH severity. Skeletal dissolution and the induction of Acid-sensing Ion Channel 1A at pH 7.94/5.70 DO mg/L provide particularly sensitive markers of OAH, with dramatic shifts in larval morphology and gene expression detected at the pH/DO transition of 7.71/3.71–7.27/2.72 mg/L. Experimental simulations that describe physiological thresholds and establish molecular markers of OAH exposure will provide fishery management with the tools to predict patterns of larval recruitment and forecast population dynamics.
Continue reading ‘Single-larva RNA sequencing reveals that red sea urchin larvae are vulnerable to co-occurring ocean acidification and hypoxia’An aquaria set-up for long-term, multiple-stressor research in marine organisms
Published 17 January 2025 Science ClosedTags: biological response, laboratory, methods, multiple factors, oxygen, temperature
- Multiple stressor research in aquaria is a useful approach to better understand the ecophysiology of marine species under different environmental conditions, including global change scenarios. Long-term experiments are helpful to detect the response of sustained exposure to selected environmental conditions. Here, we present an experimental set-up suitable to run long-term experiments, composed of a life support system, a cost-effective aquaria set-up and an open-source controller based on the use of a Raspberry Pi. In this set-up, temperature, pH and dissolved oxygen (DO) are individually manipulated and simultaneously controlled in eight different treatments.
- To prove the efficacy of the set-up, we provide an assessment over a nine-month experiment on a deep-sea coral species, combining values from current in situ and IPCC AR5 RCP 8.5 scenarios for the aforementioned parameters. Recorded data from the controllers and independent measurements (e.g. cross-checking with portable multiparameter devices and laboratory analyses) throughout the experimental time have been analysed and results have been discussed.
- Overall, the experimental set-up performed well, proving the stability of the parameters over time, both individually and in combination. On average, low and high-temperature treatments varied ~0.4 and 0.3°C, respectively. Low pH treatments were maintained within 0.05 pH units, whereas ambient pH treatments varied ~0.04 pH units. Low DO treatments had a variation of ~0.3 mg L−1, and ambient DO treatments varied ~0.2 mg L−1. No significant differences between scenarios for any parameter were detected (p < 0.05). The resulting programming code to read, control and register the values for these parameters is provided to contribute to its replicability across institutions.
- The set-up performed well over extensive periods while providing a customisable controller as a cost-effective alternative. The versatility of the system, allowing to work with different species, environments and scenarios makes it valuable for aquaria experiments where interactions of multiple environmental factors need to be tested.
Climate covariate choice and uncertainty in projecting species range shifts: a case study in the Eastern Bering Sea
Published 26 December 2024 Science ClosedTags: Arctic, biological response, crustaceans, field, fish, fisheries, modeling, multiple factors, oxygen, regionalmodeling, temperature
Species distribution models (SDMs) are critical to the adaptive management of fisheries under climate change. While many approaches projecting marine species range shifts have incorporated the effects of temperature on movement, there is a need to incorporate a wider suite of ecologically relevant predictors as temperature-based SDMs can considerably under- or over-estimate the rate of species responses to climate shocks. As a subarctic ecosystem at the sea ice margin, the Eastern Bering Sea (EBS) is warming faster than much of the global ocean, resulting in the rapid redistribution of key fishery and subsistence resources. To support long-term planning and adaptation, we combine 40 years of scientific surveys with a high-resolution oceanographic model to examine the effects of bottom temperature, oxygen, pH and a regional climate index (the extent of the EBS ‘cold pool’) on range projections through the end of the century. We use multimodel inference to partition uncertainty among earth systems models, climate scenarios and distribution model parameterizations for several ecologically and economically important EBS groundfish and crabs. Covariate choice is the primary source of uncertainty for most species, with models that account for spatial responses to the cold pool performing better and suggesting more extensive northward movements than alternative models. Models suggest declines in the probability of occurrence at low pH and oxygen concentrations for most species. We project shifts that are directionally consistent with, yet larger than those previously estimated for most species, suggesting that accounting for large-scale climate variability in species distribution models may substantially alter range projections.
Continue reading ‘Climate covariate choice and uncertainty in projecting species range shifts: a case study in the Eastern Bering Sea’Energy budget as a tool to assess the effects of environmental stressors: a study on whiteleg shrimp (Penaeus vannamei) exposed to variations in salinity and ocean acidification
Published 10 October 2024 Science ClosedTags: biological response, crustaceans, growth, laboratory, multiple factors, oxygen, physiology, salinity, temperature
Our goal was to use the energy budget as a tool to evaluate the effects of salinity (20, 25, 30, 35 or 40‰) and ocean acidification (pH 8.0 or 7.3) in Penaeus vannamei. We assessed the energy budget a range of physiological processes (ingestion, defecation, growth, metabolism, excretion, energy substrate, hepatosomatic index, and osmoregulation). In general, salinity had an accentuated effect than pH, as it altered nearly all physiological parameters, including the energy channeled into growth (up to −56%). Reduced pH also affected the energy budget: increased energy lost in feces (25 and 40‰: +21% and 13%, respectively), excretion (25‰: +55%), and metabolism (20‰: +58%). Furthermore, acidified pH increased oxygen consumption by 60%, which may be related to higher energy expenditure. In conclusion, the energy budget can be a valuable tool for assessing the impacts of environmental stressors and the salinity has an accentuated effect than the ocean acidification predicted.
Continue reading ‘Energy budget as a tool to assess the effects of environmental stressors: a study on whiteleg shrimp (Penaeus vannamei) exposed to variations in salinity and ocean acidification’How water acidification influences the organism antioxidant capacity and gill structure of Mediterranean mussel (Mytilus galloprovincialis, Lamarck, 1819) at normoxia and hypoxia
Published 24 June 2024 Science ClosedTags: biological response, Black Sea, chemistry, laboratory, molecular biology, mollusks, multiple factors, oxygen, physiology
Highlights
- Mediterranean mussels demonstrate relative tolerance to water acidification and hypoxia.
- Acidification combined with normoxia/hypoxia did not promote ROS formation and DNA damage in hemocytes.
- The activity of SOD and CAT in gills was stable upon acidification and hypoxia.
- Acidification combined with normoxia/hypoxia led to inflammation in gills and the morphological lesions of filaments
Abstract
The effect of water acidification in combination with normoxia or hypoxia on the antioxidant capacity and oxidative stress markers in gills and hemolymph of the Mediterranean mussel (Mytilus galloprovincialis), as well as on gill microstructure, has been evaluated through an in vivo experiment. Mussels were exposed to a low pH (7.3) under normal dissolved oxygen (DO) conditions (8 mg/L), and hypoxia (2 mg/L) for 8 days, and samples were collected on days 1, 3, 6, and 8 to evaluate dynamic changes of physiological responses. Cytoplasmic concentrations of reactive oxygen species (ROS) and levels of DNA damage were measured in hemocytes, while the activity of catalase (CAT) and superoxide dismutase (SOD) and histopathological changes were assessed in gills. The results revealed that while water acidification did not significantly affect the activity of SOD and CAT in gills under normoxic and hypoxic conditions, there was a trend towards suppression of CAT activity at the end of the experimental period (day 8). Similarly, we did not observe increased formation of ROS in hemocytes or changes in the levels of DNA damage during the experimental period. These results strongly suggest that the oxidative stress response system in mussels is relatively stable to experimental conditions of acidification and hypoxia. Experimental acidification under normoxia and hypoxia caused changes to the structure of the gills, leading to various histopathological alterations, including dilation, hemocyte infiltration into the hemal sinuses, intercellular edema, vacuolization of epithelial cells in gill filaments, lipofuscin accumulation, changes in the shape and adjacent gill filaments, hyperplasia, exfoliation of the epithelial layer, necrosis, swelling, and destruction of chitinous layers (chitinous rods). Most of these alterations were reversible, non-specific changes that represent a general inflammatory response and changes in the morphology of the gill filaments. The dynamics of histopathological alterations suggests an active adaptive response of gills to environmental stresses. Taken together, our data indicate that Mediterranean mussels have a relative tolerance to water acidification and hypoxia at tissue and cellular levels.
Continue reading ‘How water acidification influences the organism antioxidant capacity and gill structure of Mediterranean mussel (Mytilus galloprovincialis, Lamarck, 1819) at normoxia and hypoxia’Cross-generational plasticity in Atlantic silversides (Menidia menidia) under the combined effects of hypoxia and acidification
Published 28 May 2024 Science ClosedTags: biological response, chemistry, fish, growth, laboratory, molecular biology, morphology, multiple factors, North Atlantic, oxygen, physiology, reproduction
We investigated the potential for cross-generational plasticity to influence how offspring respond to hypoxia and ocean acidification (hereafter HypOA) in the coastal forage fish Atlantic silverside (Menidia menidia). Mature wild silversides were treated with a control [dissolved oxygen (DO):100% air saturation (a.s.) / pCO2: 650 μatm] or HypOA conditions [DO: 40% a.s. / pCO2: 2300 μatm] for 10 days prior to spawning. Their offspring were reared under both treatments in factorial experimental design. Parental acclimation to HypOA altered several offspring traits, including increased embryo survival under HypOA and an overall reduction in post-hatch growth rate. Offspring from HypOA-treated parents that were reared under control conditions had larger eyes across the developmental period. When compared against the overall control group, larvae directly exposed to HypOA exhibited 2,416 differentially expressed transcripts (DETs). Although most of these DETs were specific to individual parental treatments, the most enriched Gene Ontology terms were conserved across parental treatments, including terms related to neurotransmitter secretion, nervous system development, axon pathfinding, calcium channel activity, proteolysis, and extracellular matrix organization. Larvae from HypOA-treated parents that were reared under control conditions exhibited a shift in constitutive gene expression similar to that seen in larvae directly exposed to HypOA. This highly consistent finding indicates that parental acclimation before fertilization promotes the transcriptional frontloading of genes in offspring that are responsive to direct HypOA exposure. This highly consistent finding indicates that parental acclimation before fertilization promotes the transcriptional frontloading of genes in offspring. This effect may have primed regulatory functions in offspring that sense and respond to low DO and elevated pCO2 conditions. Though, our results suggest that this altered developmental phenotype may have some negative fitness consequences for offspring.
Continue reading ‘Cross-generational plasticity in Atlantic silversides (Menidia menidia) under the combined effects of hypoxia and acidification’Ocean deoxygenation dampens resistance of diatoms to ocean acidification in darkness
Published 23 May 2024 Science ClosedTags: abundance, biological response, chemistry, laboratory, light, morphology, multiple factors, otherprocess, oxygen, physiology, phytoplankton
Respiratory activity in the oceans is declining due to the expansion of hypoxic zones and progressive deoxygenation, posing threats to marine organisms along with impacts of concurrent ocean acidification. Therefore, understanding the combined impacts of reduced pO2 and elevated pCO2 on marine primary producers is of considerable significance. Here, to simulate diatoms’ sinking into the aphotic zone of turbid coastal water, we exposed the diatoms Thalassiosira pseudonana and Thalassiosira weissflogii in darkness at 20°C to different levels of pO2 and pCO2 conditions for ~3 weeks, and monitored their biomass density, photosynthetic activity and dark respiration, and examined their recovery upon subsequent exposure to light at 20°C, simulating surface water conditions. Along with decreased cell abundance and size, measured photosynthetic capacity and dark respiration rates in these two diatoms both gradually decreased during the prolonged darkness. Reduced pO2 alone did not negatively affect the photosynthetic machinery in both the dark-survived diatom, and enhanced their subsequent recovery upon light exposure. Nevertheless, the combination of the elevated pCO2 and reduced pO2 (equivalent to hypoxia) led to the biomass loss by about 90% in T. pseudonana, and delayed the recovery of both species upon subsequent exposure to light, though it did not reduce the cell concentration of T. weissflogii during the elongated darkness. Our results suggest that reduced O2 availability diminishes the abilities of the diatoms to cope with the acidic stress associated with ocean acidification, and the expansion of hypoxic waters could delay the photosynthetic recovery of coastal diatoms when they are transported upwards through mixing from dark layers to sunlit waters.
Continue reading ‘Ocean deoxygenation dampens resistance of diatoms to ocean acidification in darkness’Critical swimming speed of juvenile rockfishes (Sebastes) following long- and short-term exposures to acidification and deoxygenation
Published 6 March 2024 Science ClosedTags: biological response, fish, laboratory, multiple factors, North Pacific, oxygen, performance
Highlights
- Swimming ability of juvenile rockfishes declined during acute and chronic exposure to deoxygenation and acidification.
- Critical swimming speed of juvenile rockfish was more sensitive to deoxygenation than to acidification.
- The effects of acidified and deoxygenated conditions on juvenile rockfish swimming ability manifest rapidly (hours to days).
- Swimming performance of juvenile rockfish recovered after upwelling-event acidified/deoxygenated conditions had subsided.
- Despite early life history differences, black and copper rockfish had similar sensitivity to acidification and deoxygenation.
Abstract
Reef fishes in the California Current Ecosystem have evolved in habitats affected by seasonally variable, episodic upwelling of high pCO2 (acidified, low pH) and low dissolved oxygen (deoxygenated) water, which suggests that these fishes might exhibit resilience to ocean acidification (OA) and deoxygenation. Yet, how the fitness of these fish are affected by natural variability in pH and DO over short time scales remains poorly understood, as do the effects of longer-term trends in pH and DO driven by climate change. We conducted a complementary suite of experiments to study the effects of acidification and deoxygenation on the critical swimming speed (Ucrit) of juvenile copper (Sebastes caurinus) and black (S. melanops) rockfish collected from nearshore habitats in an ocean acidification “hotspot” off Northern California. We consistently observed that Ucrit declined more strongly in response to deoxygenation than to acidification, at least under ranges of these stressors consistent with current conditions and plausible future scenarios, and that reduction in swimming performance reflected additive rather than synergistic responses to concurrent exposure. Reductions in swimming performance manifested quickly–on the scale of hours–in response to exposure to elevated pCO2/reduced DO, yet are reversible: swimming performance of juvenile rockfish recovers within a matter of days, and perhaps much more quickly, after acidified/deoxygenated conditions have subsided. Insights from this study address potential effects of variability in upwelling intensity at event and seasonal scales for nearshore rockfishes and contribute to our understanding of fish responses to future ocean conditions driven by ongoing climate change.
Continue reading ‘Critical swimming speed of juvenile rockfishes (Sebastes) following long- and short-term exposures to acidification and deoxygenation’Whole transcriptome analysis of demersal fish eggs reveals complex responses to ocean deoxygenation and acidification
Published 26 February 2024 Science ClosedTags: biological response, fish, laboratory, molecular biology, multiple factors, North Pacific, oxygen
Highlights
- We assessed fish eggs’ gene expression to ocean acidification and deoxygenation.
- Low oxygen’s effect on gene expression was more pronounced than high pCO2.
- Glycolytic genes showed increased expression under low oxygen condition.
- Apparent mitigation of gene expression was dominant in combined stress conditions.
Abstract
Ocean acidification and deoxygenation co-occur in marine environments, causing deterioration of marine ecosystems. However, effects of compound stresses on marine organisms and their physiological coping mechanisms are largely unknown. Here, we show how high pCO2 and low dissolved oxygen (DO) cause transcriptomic changes in eggs of a demersal fish (Sillago japonica), which are fully exposed to such stresses in natural environment. Overall gene expression was affected more strongly by low DO than by high pCO2. Enrichment analysis detected significant stress responses such as glycolytic processes in response to low DO. Increased expression of a group of glycolytic genes under low DO conditions is presumably because oxygen depletion disables the electron transfer pathway, complementing ATP production in the glycolytic pathway. Contrary to expectations, apparent mitigation of gene expression changes was dominant under combined stress conditions and may represent an innate fish adaptive trait for severe environments.
Continue reading ‘Whole transcriptome analysis of demersal fish eggs reveals complex responses to ocean deoxygenation and acidification’Reviews and syntheses: The clam before the storm – a meta-analysis showing the effect of combined climate change stressors on bivalves
Published 6 February 2024 Science ClosedTags: biological response, growth, mollusks, morphology, multiple factors, oxygen, review, salinity, temperature
The impacts of climate change on marine organisms have been increasingly documented in laboratory and experimental studies. However, the use of different taxonomic groupings and the assessment of a range of processes make identifying overall trends challenging. Meta-analysis has been used to determine general trends, but coarse taxonomic granularity may mask phylogenetically specific responses. Bivalve molluscs are a data-rich clade of ecologically and economically important calcifying marine taxa that allow for the assessment of species-specific vulnerability across developmental stages. Drawing on the large body of available literature, we conduct a meta-analysis of 203 unique experimental set-ups in order to examine how bivalve growth responds to increased water temperature, acidity, deoxygenation, and changes in salinity in 10 climate change stressor combinations. This is the most complete examination of bivalve responses to date and shows that anthropogenic climate change will disproportionally affect particular families, suggesting taxonomic differentiation in climate change response. Specifically, Mytilidae, Ostreidae, and Pectinidae (67 % of experiments) respond with negative effect sizes for all individual stressors, whereas responses in Pinnidae, Tellinidae, and Veneridae are more complex. Our analysis shows that earlier studies reporting negative impacts on bivalves are driven by only three or four well-studied, commercially important families. Despite the taxonomic differentiation, almost all drivers and their combinations have significant negative effects on growth. The synergistic impacts of deoxygenation, acidification, and temperature result in the largest negative effect size. Infaunal taxa, including Tellinidae and Veneridae, appear more resistant to warming and oxygen reduction than epifaunal or motile taxa, but this difference between the two taxa is also based on a small number of data points. The current focus of experimental set-ups on commercially important taxa and families within a small geographic range creates gaps in the understanding of global impacts on these economically important foundation organisms.
Continue reading ‘Reviews and syntheses: The clam before the storm – a meta-analysis showing the effect of combined climate change stressors on bivalves’Sometimes (often?) responses to multiple stressors can be predicted from single-stressor effects: a case study using an agent-based population model of croaker in the Gulf of Mexico
Published 18 January 2024 Science ClosedTags: abundance, biological response, BRcommunity, communitymodeling, fish, individualmodeling, modeling, morphology, mortality, multiple factors, North Atlantic, otherprocess, oxygen, performance, reproduction, temperature
Abstract
Objective
Rapid changes in the world’s oceans make assessment of fish population responses to multiple stressors, especially on scales relevant to management, increasingly important. I used an existing agent-based, spatially explicit model of Atlantic Croaker Micropogonias undulatus in the northern Gulf of Mexico to examine how temperature, hypoxia, and ocean acidification, singly and in combinations, affect long-term population dynamics.
Methods
I performed a factorial simulation experiment with each stressor at three levels and analyzed various treatment combinations to assess the additivity and multiplicity of interactions. The response variables were long-term equilibrium (final year) values of spawning stock biomass (SSB), recruitment, weight at age, and two measures of stock productivity (recruits per SSB and maximum recruitment) derived from the spawner–recruit relationship fitted to model output. I used the single-stressor effects from the experiment to predict how the response variables would change when all three stressors were changed. Single-stressor effects were combined as the sum of the fractional changes (additive scale) and the product of ratios of changes (multiplicative scale) and compared to the responses in simulations with all stressors imposed.
Result
Analyzing the factorial design for two-way and three-way interactions showed that there were many interactions on the additive scale but very few on the multiplicative scale. Thus, the responses to multiple stressors were well predicted from single stressor effects when combined as multiplicative effects.
Conclusion
I discuss how the lack of strong interactions could be due to model assumptions, the structure of the model, or oversimplified representation of stressor effects. Alternatively, the model and analysis may be sufficiently realistic and weak interactions on the multiplicative scale may be common. This would reduce a complicated multi-factor situation to a series of more tractable single-factor effects. A critical next step is to determine how we can a priori identify situations of low interactions (i.e., predictable from single-stressor effects) without having to already know the multi-stressor response.
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Continue reading ‘Sometimes (often?) responses to multiple stressors can be predicted from single-stressor effects: a case study using an agent-based population model of croaker in the Gulf of Mexico’Assessing impacts of coastal warming, acidification, and deoxygenation on Pacific oyster (Crassostrea gigas) farming: a case study in the Hinase area, Okayama Prefecture, and Shizugawa Bay, Miyagi Prefecture, Japan (Update)
Published 24 November 2023 Science ClosedTags: biological response, chemistry, field, fisheries, modeling, mollusks, morphology, multiple factors, North Pacific, oxygen, regionalmodeling, reproduction, temperature
Coastal warming, acidification, and deoxygenation are progressing primarily due to the increase in anthropogenic CO2. Coastal acidification has been reported to have effects that are anticipated to become more severe as acidification progresses, including inhibiting the formation of shells of calcifying organisms such as shellfish, which include Pacific oysters (Crassostrea gigas), one of the most important aquaculture resources in Japan. Moreover, there is concern regarding the combined impacts of coastal warming, acidification, and deoxygenation on Pacific oysters. However, spatiotemporal variations in acidification and deoxygenation indicators such as pH, the aragonite saturation state (Ωarag), and dissolved oxygen have not been observed and projected in oceanic Pacific oyster farms in Japan. To assess the present impacts and project future impacts of coastal warming, acidification, and deoxygenation on Pacific oysters, we performed continuous in situ monitoring, numerical modeling, and microscopic examination of Pacific oyster larvae in the Hinase area of Okayama Prefecture and Shizugawa Bay in Miyagi Prefecture, Japan, both of which are famous for their Pacific oyster farms. Our monitoring results first found Ωarag values lower than the critical level of acidification for Pacific oyster larvae in Hinase, although no impact of acidification on larvae was identified by microscopic examination. Our modeling results suggest that Pacific oyster larvae are anticipated to be affected more seriously by the combined impacts of coastal warming and acidification, with lower pH and Ωarag values and a prolonged spawning period, which may shorten the oyster shipping period and lower the quality of oysters.
Continue reading ‘Assessing impacts of coastal warming, acidification, and deoxygenation on Pacific oyster (Crassostrea gigas) farming: a case study in the Hinase area, Okayama Prefecture, and Shizugawa Bay, Miyagi Prefecture, Japan (Update)’Atlantic-origin water extension into the Pacific Arctic induced an anomalous biogeochemical event
Published 15 November 2023 Science ClosedTags: Arctic, biogeochemistry, chemistry, field, fisheries, modeling, multiple factors, nutrients, oxygen, policy, regionalmodeling, salinity
The Arctic Ocean is facing dramatic environmental and ecosystem changes. In this context, an international multiship survey project was undertaken in 2020 to obtain current baseline data. During the survey, unusually low dissolved oxygen and acidified water were found in a high-seas fishable area of the western (Pacific-side) Arctic Ocean. Herein, we show that the Beaufort Gyre shrinks to the east of an ocean ridge and forms a front between the water within the gyre and the water from the eastern (Atlantic-side) Arctic. That phenomenon triggers a frontal northward flow along the ocean ridge. This flow likely transports the low oxygen and acidified water toward the high-seas fishable area; similar biogeochemical properties had previously been observed only on the shelf-slope north of the East Siberian Sea.
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Fig. 1: Schematic of the Arctic Ocean circulation and the study area with hydrographic stations.
a, b Maps of the Arctic Ocean and the study area. In a, yellow, blue, and red arrows represent flows from the shelf-slope at the north of the East Siberian Sea (ESS), and from the Pacific and Atlantic oceans in 2017–2020. Ocean circulation and water masses are abbreviated as follows: Beaufort Gyre (BG), Transpolar Drift (TPD), Pacific Water (PW), Lower Halocline Water (LHW), and Atlantic Water (AW). Geographical locations are abbreviated as follows: Canada Basin (CB), Chukchi Plateau (CP), Mendeleyev Ridge (MR), Makarov Basin (MB), and Lomonosov Ridge (LR). In b red, green, and blue dots denote the hydrographic stations conducted by the Research Vessel (R/V) Araon (Korea), R/V Mirai (Japan), and Canadian Coast Guard Ship Louis S. St-Laurent (Canada), under the 2020 Synoptic Arctic Survey project. Black dots indicate other hydrographic stations between 2002 and 2019 listed in Supplementary Table 1.
Continue reading ‘Atlantic-origin water extension into the Pacific Arctic induced an anomalous biogeochemical event’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’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’Response of foraminifera Ammonia confertitesta (T6) to ocean acidification, warming, and deoxygenation – an experimental approach
Published 4 September 2023 Science ClosedTags: biological response, calcification, laboratory, morphology, mortality, multiple factors, North Atlantic, oxygen, physiology, protists, temperature
Ocean acidification, warmer temperatures, and the expansion of hypoxic zones in coastal areas are direct consequences of the increase in anthropogenic activities. However, so far, the combined effects of these stressors on calcium carbonate-secreting marine microorganisms – foraminifera are complex and poorly understood. This study reports the foraminiferal survival behavior, and geochemical trace elements incorporation measured from the shells of living cultured benthic foraminifera from the Gullmar fjord (Sweden) after exposure to warming, acidification, and hypoxic conditions. An experimental set-up was designed with two different temperatures (fjord’s in-situ 9 ˚C and 14 ˚C), two different oxygen concentrations (oxic versus hypoxic), and three different pH (control, medium, and low pH based on the IPCC scenario for the year 2100). Duplicate aquariums, meaning aquariums displaying the same conditions and same number of species, were employed for the controls and the two lower pH conditions at both temperatures. The stability of the aquariums was ensured by regular measurement of the water parameters and confirmed by statistical analysis. The species Ammonia confertitesta’s (T6) survival (CTB-labeled), shell calcification (calcein-labeled), and geochemical analyses (laser-ablation ICP-MS) were investigated at the end of the experimental period (48 days). Investigated trace elements (TE) ratios were Mg/Ca, Mn/Ca, Ba/Ca, and Sr/ Ca. Results show that A. confertitesta (T6) calcified chambers in all the experimental conditions except for the most severe combination of stressors (i.e., warm, hypoxic, low pH). Survival rates varied by up to a factor of two between duplicates for all conditions suggesting that foraminiferal response may not solely be driven by environmental conditions but also by internal or confounding factors (e.g., physiological stress). A large variability of all the TE/Ca values of foraminifera growing at low pH is observed suggesting that A. confertitesta (T6) may struggle to calcify in these conditions. Thus, this study demonstrates the vulnerability of a resilient species to the triple-stressor scenario in terms of survival, calcification, and trace element incorporation. Overall, the experimental set-up yielded coherent results compared to previous studies in terms of ontogeny, trace elements ratios, and partition coefficient making it advantageous for environmental reconstructions.
Continue reading ‘Response of foraminifera Ammonia confertitesta (T6) to ocean acidification, warming, and deoxygenation – an experimental approach’
