Whilst crustaceans occupy a diversity of ecological niches and have adapted to many environmental challenges, relatively little is known on how the predicted changes associated with climate change will impact individuals, communities, species and ecosystems globally. Direct oceanic change to seawater temperature, pH, alkalinity, oxygen level and salinity and indirect impacts on weather, seasonality, food availability and changes in ecological networks will put pressure upon crustaceans to acclimate. There is now emerging evidence that behaviour, physiology, fitness and ultimately reproduction and survival of coastal crustaceans is altered under experimental climate change conditions, with most studies showing negative impacts. Nevertheless measurable endpoints, multigenerational and ecosystem studies are to date extremely rare and the full impact of climate change stress upon crustaceans is nowhere near fully understood.
Continue reading ‘Crustacean ecology in a changing climate’Posts Tagged 'oxygen'
Crustacean ecology in a changing climate
Published 4 November 2022 Science ClosedTags: biological response, crustaceans, mortality, multiple factors, oxygen, physiology, reproduction, review, salinity, temperature
Impacts of global environmental change on fish and fisheries of the Northeastern Pacific Ocean
Published 2 November 2022 Science ClosedTags: biological response, fish, fisheries, laboratory, mortality, multiple factors, North Pacific, oxygen, physiology, reproduction, temperature
Marine fishes’ intolerance to global change conditions can affect the abundance and distribution of ecologically and economically important species, reshape the structure of trophic webs, and profoundly impact the human communities that rely on fished species for their livelihood and culture. Only by understanding the vulnerability of fished species and fishing communities to global change can we take effective adaptive action and implement climate-ready fisheries management. In this dissertation, I investigate the vulnerability of eight commercially important fished species and one fishing community to global change in the Northeastern Pacific Ocean. In chapter one, I expose Lingcod (Ophiodon elongatus), a benthic egg layer, to temperature, oxygen, and pH conditions we expect to see in the Central California Current System (CCS) by the year 2050 and 2100. I examine both the lethal and sublethal effects of these two multistressor climate change scenarios by measuring differences in metabolic rate, hatching success, and larval quality between treatments. In chapter two, I use a species distribution modeling approach to evaluate how historical (1982-2019) and projected (2030 through end-of-century) warming in the Eastern Bering Sea (EBS), Alaska, affects predator-prey interactions for some of the most commercially valuable fisheries in the U.S. These species include: 1) Pacific Cod (Gadus macrocephalus), 2) Pacific Halibut (Hippoglossus stenolepis), 3) Arrowtooth Flounder, 4) Walleye Pollock (Gadus chalcogrammus), 5) Tanner Crab (Chionoecetes bairdi), 6) Snow Crab (Chionoecetes opilio), and 7) Alaskan Pink Shrimp (Pandalus eous). In chapter three, I use social network analyses to depict the resilience and adaptability of the California Market Squid fishery (Doryteuthis opalescens), the most valuable in the state, to climate perturbations and project changes in habitat suitability by the year 2100 in the CCS. By using all of these vulnerability assessment tools, we can begin to prepare U.S. west coast fisheries for global environmental change.
Continue reading ‘Impacts of global environmental change on fish and fisheries of the Northeastern Pacific Ocean’Coral reef fishes in a multi-stressor world
Published 1 November 2022 Science ClosedTags: biological response, fish, mitigation, multiple factors, noise, oxygen, pathogens, predation, review, salinity, temperature, toxicants
Coral reef fishes and the ecosystems they support represent some of the most biodiverse and productive ecosystems on the planet yet are under threat as they face dramatic increases in multiple, interacting stressors that are largely intensified by anthropogenic influences, such as climate change. Coral reef fishes have been the topic of 875 studies between 1979 and 2020 examining physiological responses to various abiotic and biotic stressors. Here, we highlight the current state of knowledge regarding coral reef fishes’ responses to eight key abiotic stressors (i.e., pollutants, temperature, hypoxia and ocean deoxygenation, pH/CO2, noise, salinity, pressure/depth, and turbidity) and four key biotic stressors (i.e., prey abundance, predator threats, parasites, and disease) and discuss stressors that have been examined in combination. We conclude with a horizon scan to discuss acclimation and adaptation, technological advances, knowledge gaps, and the future of physiological research on coral reef fishes. As we proceed through this new epoch, the Anthropocene, it is critical that the scientific and general communities work to recognize the issues that various habitats and ecosystems, such as coral reefs and the fishes that depend on and support them, are facing so that mitigation strategies can be implemented to protect biodiversity and ecosystem health.
Continue reading ‘Coral reef fishes in a multi-stressor world’How does climate change affect a fishable resource? The case of the royal sea cucumber (Parastichopus regalis) in the central Mediterranean Sea
Published 10 October 2022 Science ClosedTags: biological response, echinoderms, fisheries, Mediterranean, multiple factors, oxygen, photosynthesis, salinity
Holothurians or sea cucumbers are key organisms in marine ecosystems that, by ingesting large quantities of sediments, provide important ecosystem services. Among them, Parastichopus regalis (Cuvier, 1817) is one of the living sea cucumbers in the Mediterranean actively fished for human consumption mainly in Spain, where it is considered a gastronomic delicacy. In the Strait of Sicily (central Mediterranean Sea), this species is not exploited for commercial use even if it is used as bait by longline fishery. P. regalis is frequently caught by bottom trawling and discarded at sea by fishers after catch, and because of its capacity to resist air exposition (at least in cold months), it is reasonable to consider that it is not affected by fishing mortality. Having observed a significant decrease in abundance since 2018, the possible effects of some ecological factors related to current climate change (i.e., temperature and pH) were sought. Generalized additive models (GAMs) were applied to investigate the relationship among the abundance of P. regalis and environmental variables and fishing effort. Long time series of P. regalis densities (2008–2021) were extracted from the MEDITS bottom trawling survey and modeled as function of environmental parameters (i.e., salinity, dissolved oxygen, ammonium, pH, and chlorophyll α) and fishing effort (i.e., total number of fishing days per gross tonnage). Our results showed that this species prefers the soft bottoms (50–200 m) of the Adventure Bank and Malta Plateau, and its distribution changed over time with a slight deepening and a rarefaction of spatial distribution starting from 2011 and 2017, respectively. In addition, a positive relationship with pH concentration in surface waters during the larval dispersal phase (3-year lag before the survey) and nutrient concentration at sea bottom (1-year lag) has been found, suggesting that this species is sensitive to climate change and food availability. This study adds new knowledge about the population dynamics of an unexploited stock of P. regalis under fishing impact and environmental under climate change in fisheries management.
Continue reading ‘How does climate change affect a fishable resource? The case of the royal sea cucumber (Parastichopus regalis) in the central Mediterranean Sea’Immune defense in hypoxic waters: impacts of CO2 acidification
Published 4 October 2022 Science ClosedTags: biological response, crustaceans, mollusks, multiple factors, oxygen, review
Periodic episodes of low oxygen (hypoxia) and elevated CO2 (hypercapnia) accompanied by low pH occur naturally in estuarine environments. Under the influence of climate change, the geographic range and intensity of hypoxia and hypercapnic hypoxia are predicted to increase, potentially jeopardizing the survival of economically and ecologically important organisms that use estuaries as habitat and nursery grounds. In this review we synthesize data from published studies that evaluate the impact of hypoxia and hypercapnic hypoxia on the ability of crustaceans and bivalve molluscs to defend themselves against potential microbial pathogens. Available data indicate that hypoxia generally has suppressive effects on host immunity against bacterial pathogens as measured by in vitro and in vivo assays. Few studies have documented the effects of hypercapnic hypoxia on crustaceans or bivalve immune defense, with a range of outcomes suggesting that added CO2 might have additive, negative, or no interactions with the effects of hypoxia alone. This synthesis points to the need for more partial pressure of O2 × low pH factorial design experiments and recommends the development of new host∶pathogen challenge models incorporating natural transmission of a wide range of viruses, bacteria, and parasites, along with novel in vivo tracking systems that better quantify how pathogens interact with their hosts in real time under laboratory and field conditions.
Continue reading ‘Immune defense in hypoxic waters: impacts of CO2 acidification’Impact of intermittent convection in the northwestern Mediterranean Sea on oxygen content, nutrients and the carbonate system
Published 2 September 2022 Science ClosedTags: chemistry, field, Mediterranean, multiple factors, nutrients, oxygen
Abstract
Using Argo profiling floats, cruises and mooring data, we reconstructed the dissolved oxygen (O2) dynamics in the Gulf of Lion and the Ligurian Sea, with a focus on the intermediate waters. By applying the CANYON-MED neural network-based method on the large network of O2-equipped Argo floats we derived nutrients and carbonate system variables in the Gulf of Lion and the Ligurian Sea at different depths in the water column and derived trends over the 2012-2020 period. In these waters, the O2 minimum is strongly affected by the intermittent convection process, and the two areas show dissimilar responses to the mixing events. In the absence of deep convection events, the O2-depleted layer tends to spread vertically and intensify even more so in the Ligurian than in the Gulf of Lion. In both areas, over the 2012-2020 period, nutrients increase overall in deep layers, with a concomitant impact on nutrient molar ratios tending towards an increase in P-limitation. Acidification estimates derived in different layers of the water column show an overall increase in dissolved inorganic carbon and a concurrent pH decrease. These trends were strongly affected by convection events slowing down the overall acidification trend.
Key Points
- In the absence of deep convection events, the O2-depleted layer spreads vertically and intensifies more in the Ligurian than Gulf of Lion.
- Nutrients increase in deep and to a lesser extent in intermediate waters with a decoupling between nitrate and phosphate trends.
- Dissolved inorganic carbon increases in intermediate and deep waters with a concurrent pH decrease over the period of study, 2012-2020.
Offshore extinctions: ocean acidification impacting interstitial fauna
Published 18 August 2022 Science ClosedTags: biological response, BRcommunity, community composition, methods, multiple factors, otherprocess, oxygen, review, sediment
As problematic as global warming, ocean acidification is a widespread problem, but the consequences of the interstitial fauna are still underrated. The biodiversity within sandy beaches is out of measurement, and its loss will be significantly felt. Estimations of the number of species are still vague. Acting as a key role in the trophic net, the interstitial organisms are threatened by pH value changes. Changing the pH values is already linked with less species richness and weakness of the sea community. The sediments may not be a sufficient buffer. Beyond this, there is another environmental problem aggravating the scenario. The decreasing complexity in the sand structure generated by the destruction of biological-generated sediments will impact the local biodiversity. Other environmental situations such as lack of sufficient O2 levels may be an aggravating combination. Here, I propose a protocol to observe if occur offshore extinctions, the veiled extinctions of interstitial fauna.
Continue reading ‘Offshore extinctions: ocean acidification impacting interstitial fauna’Physical-chemical factors influencing the vertical distribution of phototrophic pico-nanoplankton in the Oxygen Minimum Zone (OMZ) off Northern Chile: the relative influence of low pH/low O2 conditions
Published 11 August 2022 Science ClosedTags: biological response, chemistry, field, multiple factors, oxygen, photosynthesis, phytoplankton, South Atlantic
Highlights
- Pico-nano eukaryotes and phototrophic nanoflagellates showed high abundances in the upper layer decreasing in abundance down to the upper oxycline.
- Temperature, oxygen, and carbonate chemistry parameters (pH and dissolved inorganic carbon, DIC) influenced significantly the vertical distribution of phototrophic pico-nanoplankton.
- The phototrophic nanoflagellate Imantonia sp. upon an experimental treatment mimicking OMZ conditions, declined dramatically, suggesting this nanoflagellate did not survive upon such conditions.
Abstract
The vertical distribution of phytoplankton is of fundamental importance in the structure, dynamic, and biogeochemical pathways in marine ecosystems. Nevertheless, what are the main factors determining this distribution remains as an open question. Here, we evaluated the relative influence of environmental factors that might control the coexistence and vertical distribution of pico-nanoplankton associated with the OMZ off northern Chile. Our results showed that in the upper layer Synechococcus-like cells were numerically important at all sampling stations. Pico-nano eukaryotes and phototrophic nanoflagellates (PNF) also showed high abundances in the upper layer decreasing in abundance down to the upper oxycline, while only Prochlorococcus showed high abundances under oxycline and within the oxygen-depleted layer. Statistical analyses evidenced that temperature, oxygen, and carbonate chemistry parameters (pH and dissolved inorganic carbon, DIC) influenced significantly the vertical distribution of phototrophic pico-nanoplankton. Additionally, we experimentally-evaluated the combined effect of low pH/low O2 conditions on a nanophytoplankton species, the haptophyte Imantonia sp. Under control conditions (pH = 8.1; O2 = 287.5 μM, light = 169.6 μEm−2s−1), Imantonia sp. in vivo fluorescence increased over fifty times, inducing supersaturated O2 conditions (900 μM) and an increasing pH (8.5), whereas upon an experimental treatment mimicking OMZ conditions (pH = 7.5; O2 = 55.6 μM; light = 169.6 μEm−2s−1), in vivo fluorescence declined dramatically, suggesting that Imantonia sp. did not survive. Although preliminary, our study provides evidence about the role of low pH/low O2 conditions on the vertical distribution of nanophytoplankton, which deserve future attention through both fieldwork and more extended experimental experiences.
Continue reading ‘Physical-chemical factors influencing the vertical distribution of phototrophic pico-nanoplankton in the Oxygen Minimum Zone (OMZ) off Northern Chile: the relative influence of low pH/low O2 conditions’The impacts of climate change on blackeye goby, Rhinogobiops nicholsii, stress responses, reproduction, and offspring fitness
Published 8 August 2022 Science ClosedTags: biological response, fish, morphology, multiple factors, oxygen, physiology, reproduction
Along with warming and sea level rise, the increasing intensity of ocean acidification (OA) and hypoxia events in coastal environments is of large concern as climate change progresses. Weakened immune function, altered reproductive output, reduced aerobic scope, and hyperventilation are just some of the ways OA and hypoxia negatively affect fish. Under stress, such as OA or hypoxia, fish will produce the hormone cortisol to maintain homeostasis, so cortisol concentration can be used to determine the relative stress an animal is experiencing. This study evaluated the stress response of adult female blackeye gobies under both acute and chronic exposure to environmental stressors by measuring muscular cortisol concentrations at specific time points from fish placed in one of four different treatments: control (8.1 pH; ~9 mg/L O2), low DO (8.1 pH; 2.0 mg/L O2), low pH (7.3 pH; ~9 mg/L O2), and a combination of low DO and low pH (7.3 pH; 2.0 mg/L O2). Additionally, some larval fish rely entirely on maternally derived hormones supplied by the yolk sac immediately after hatching. An increase in cortisol in the yolk supply may cause developmental disadvantages, but there is also evidence that it can better equip offspring to face the stressors experienced by their mothers. Therefore, the relationship between maternal muscular and whole egg cortisol concentrations was investigated with females laying clutches under each of the four treatments. After spawning, clutches were split to be incubated under the same conditions their mothers experienced or the control treatment. At 1 day post hatch, offspring physiological fitness was evaluated based on morphometric characteristics and standard metabolic rate. This study observed that adult female blackeye gobies experiencing acute stress tend to have higher cortisol concentrations than those under chronic stress. While under acute stress, blackeye gobies had the strongest stress response under the low pH treatment, followed by the combined stressors, with the response to the low DO treatment being the weakest. While under chronic stress, blackeye gobies had the highest sustained cortisol values while under the combined treatment, then the low pH treatment, with the lowest values under the low DO treatment. Low DO and low pH were also found to act antagonistically on the blackeye goby stress response. When evaluating how stress is translated generationally, a positive relationship between maternal and egg cortisol concentrations was found across the four treatments. However, blackeye gobies were not able to successfully fertilize eggs under the low pH or combined treatment. In addition, clutches with higher initial cortisol concentrations showed trends of increased time to hatching and standard metabolic rate and decreased length and weight at 1 day post hatch. The results of this study suggest decreased pH and dissolved oxygen are harmful to both adult and larval blackeye gobies. Due to the disruption of successful reproduction under low pH and the developmental and physiological disadvantages under low DO, future populations of blackeye gobies could suffer greatly as anthropogenic climate change progresses.
Continue reading ‘The impacts of climate change on blackeye goby, Rhinogobiops nicholsii, stress responses, reproduction, and offspring fitness’Ramifications of climate change induced by anthropogenic factors on global fish population scenario
Published 3 August 2022 Science ClosedTags: biological response, BRcommunity, fish, fisheries, morphology, mortality, multiple factors, oxygen, review, temperature
One of the important consequences of climate change is its effect on the global fish population. Though not very highly pronounced each year, the effect of climate change is of cumulative nature. Global aquaculture is being affected by temperature changes of both water and air. Fluctuations in the ocean surface temperatures, ocean current patterns, wind speeds, and wave directions, all have its impact on aquaculture. Each year we see more and more incidences of extreme weather conditions in different parts of the world, be it in the form of hurricanes, heavy floods, etc. Fishes are subjected to various stress factors which in turn take a toll on its growth and development. This can lead to lower weight gain and increased mortality due to higher susceptibility to diseases. This, coupled with direct unsustainable anthropogenic activities in the oceans and rivers may lead to collapse of the marine and freshwater ecosystem. Recent studies have identified specific regions where marine aquaculture production will be positively and negatively affected. One of the sustainable ways of developing aquaculture in the coming decades would be by developing region-wise strategies to maintain or increase fish population levels and thus meet the global seafood demands even in 2050. The current review is an attempt to assess the effects of ocean warming, ocean acidification, and ocean deoxygenation on the growth, survival, and diversity of marine lifeforms and suggest ways to stop a complete collapse of marine fish population by 2050, the year for which the complete collapse is predicted based on projections.
Continue reading ‘Ramifications of climate change induced by anthropogenic factors on global fish population scenario’Biological sensitivities to high-resolution climate change projections in the California current marine ecosystem
Published 29 July 2022 Science ClosedTags: biological response, crustaceans, fish, modeling, mollusks, multiple factors, oxygen, performance, phanerogams, physiology, regionalmodeling, temperature
The California Current Marine Ecosystem is a highly productive system that exhibits strong natural variability and vulnerability to anthropogenic climate trends. Relating projections of ocean change to biological sensitivities requires detailed synthesis of experimental results. Here, we combine measured biological sensitivities with high-resolution climate projections of key variables (temperature, oxygen, and pCO2) to identify the direction, magnitude, and spatial distribution of organism-scale vulnerabilities to multiple axes of projected ocean change. Among 12 selected species of cultural and economic importance, we find that all are sensitive to projected changes in ocean conditions through responses that affect individual performance or population processes. Response indices were largest in the northern region and inner shelf. While performance traits generally increased with projected changes, fitness traits generally decreased, indicating that concurrent stresses can lead to fitness loss. For two species, combining sensitivities to temperature and oxygen changes through the Metabolic Index shows how aerobic habitat availability could be compressed under future conditions. Our results suggest substantial and specific ecological susceptibility in the next 80 years, including potential regional loss of canopy-forming kelp, changes in nearshore food webs caused by declining rates of survival among red urchins, Dungeness crab, and razor clams, and loss of aerobic habitat for anchovy and pink shrimp. We also highlight fillable gaps in knowledge, including specific physiological responses to stressors, variation in responses across life stages, and responses to multistressor combinations. These findings strengthen the case for filling information gaps with experiments focused on fitness-related responses and those that can be used to parameterize integrative physiological models, and suggest that the CCME is susceptible to substantial changes to ecosystem structure and function within this century.
Continue reading ‘Biological sensitivities to high-resolution climate change projections in the California current marine ecosystem’Assessing the vulnerability of marine life to climate change in the Pacific Islands region
Published 15 July 2022 Science ClosedTags: biological response, multiple factors, oxygen, reproduction, South Pacific, temperature
Our changing climate poses growing challenges for effective management of marine life, ocean ecosystems, and human communities. Which species are most vulnerable to climate change, and where should management focus efforts to reduce these risks? To address these questions, the National Oceanic and Atmospheric Administration (NOAA) Fisheries Climate Science Strategy called for vulnerability assessments in each of NOAA’s ocean regions. The Pacific Islands Vulnerability Assessment (PIVA) project assessed the susceptibility of 83 marine species to the impacts of climate change projected to 2055. In a standard Rapid Vulnerability Assessment framework, this project applied expert knowledge, literature review, and climate projection models to synthesize the best available science towards answering these questions. Here we: (1) provide a relative climate vulnerability ranking across species; (2) identify key attributes and factors that drive vulnerability; and (3) identify critical data gaps in understanding climate change impacts to marine life. The invertebrate group was ranked most vulnerable and pelagic and coastal groups not associated with coral reefs were ranked least vulnerable. Sea surface temperature, ocean acidification, and oxygen concentration were the main exposure drivers of vulnerability. Early Life History Survival and Settlement Requirements was the most data deficient of the sensitivity attributes considered in the assessment. The sensitivity of many coral reef fishes ranged between Low and Moderate, which is likely underestimated given that reef species depend on a biogenic habitat that is extremely threatened by climate change. The standard assessment methodology originally developed in the Northeast US, did not capture the additional complexity of the Pacific region, such as the diversity, varied horizontal and vertical distributions, extent of coral reef habitats, the degree of dependence on vulnerable habitat, and wide range of taxa, including data-poor species. Within these limitations, this project identified research needs to sustain marine life in a changing climate.
Continue reading ‘Assessing the vulnerability of marine life to climate change in the Pacific Islands region’Micro- and nanoplastics effects in a multiple stressed marine environment
Published 11 July 2022 Science ClosedTags: biological response, multiple factors, oxygen, review, toxicants
Highlights
- MNPs in the environment are complex mixtures of various size ranges, shapes, polymers
- MNPs and global change driven stressors do not operate in isolation
- Stress responses of biota due to MNPs should be contextualised in a changing environment
- Reports indicate that MNPs interact with OW and OA and impact biota
- Effects of MNPs combined with global change stressors at population level are unknown
Abstract
Micro- and nanoplastics (MNPs) pollution is an environmental issue of concern, but current effect assessments often overlook realistic scenarios, and a contextualised vision of the magnitude of the impact of complex mixtures of MNPs together with other environmental stressors is urgently needed. Plastic particles exist in the environment as complex mixtures of particles from various size ranges, shapes, and polymer types, but the potential effects of realistic MNPs mixtures and concentrations are still poorly understood, and current effects data is insufficient to produce high quality risk assessments. Organisms exposed to MNPs in the marine environment are simultaneously subjected to global change driven stressors, among others, such as ocean warming (OW), marine heat waves (MHW), ocean acidification (OA), and ocean deoxygenation (OD). Stress responses due to MNPs ingestion can, in particular cases, lead to a metabolic and energetic cost, which may be aggravated in the case of organisms already vulnerable due to simultaneous exposure to global change-related stressors. In this work, we discuss how MNPs effects could be assessed while considering plastics complexity and other environmental stressors. We identify knowledge gaps in MNPs assessments, acknowledge the importance of environmental data acquisition and availability for improved assessments, and consider how mechanistic ecological models can be used to unveil and to increase our understanding of MNPs effects on marine ecosystems. Understanding the importance of plastic pollution in the context of other stressors such as climate change and their potential combined effects on marine ecosystems is important. The assessment of realistic effects of MNPs on all biological levels of organisation should consider the co-occurrence in the environment of global change-related stressors. Even though the number of studies is still limited, recent effect assessment reports indicate that the MNPs interaction with global change stressors can affect processes in organisms such as ingestion and digestion, energy allocation, growth, and fecundity. The potential impact of this interaction at population levels is largely unknown and requires increased attention from the research community, to provide information to stakeholders on the vulnerability of marine species and ecosystems now and under future environmental conditions.
Continue reading ‘Micro- and nanoplastics effects in a multiple stressed marine environment’Perceived intensification in harmful algal blooms is a wave of cumulative threat to the aquatic ecosystems
Published 16 June 2022 Science ClosedTags: biological response, multiple factors, oxygen, physiology, phytoplankton, prokaryotes, review, temperature
Aquatic pollution is considered a major threat to sustainable development across the world, and deterioration of aquatic ecosystems is caused usually by harmful algal blooms (HABs). In recent times, HABs have gained attention from scientists to better understand these phenomena given that these blooms are increasing in intensity and distribution with considerable impacts on aquatic ecosystems. Many exogenous factors such as variations in climatic patterns, eutrophication, wind blowing, dust storms, and upwelling of water currents form these blooms. Globally, the HAB formation is increasing the toxicity in the natural water sources, ultimately leading the deleterious and hazardous effects on the aquatic fauna and flora. This review summarizes the types of HABs with their potential effects, toxicity, grazing defense, human health impacts, management, and control of these harmful entities. This review offers a systematic approach towards the understanding of HABs, eliciting to rethink the increasing threat caused by HABs in aquatic ecosystems across the world. Therefore, to mitigate this increasing threat to aquatic environments, advanced scientific research in ecology and environmental sciences should be prioritized.
Continue reading ‘Perceived intensification in harmful algal blooms is a wave of cumulative threat to the aquatic ecosystems’Long-term exposure to an extreme environment induces species-specific responses in corals’ photosynthesis and respiration rates
Published 7 June 2022 Science ClosedTags: adaptation, biological response, BRcommunity, corals, laboratory, multiple factors, otherprocess, oxygen, photosynthesis, protists, respiration, South Pacific, temperature
Extreme reef environments have become useful natural laboratories to investigate physiological specificities of species chronically exposed to future-like climatic conditions. The lagoon of Bouraké in New Caledonia (21°56′56.16′′ S; 125°59′36.82′′ E) is one of the only reef environments studied where the three main climatic stressors predicted to most severely impact corals occur. In this lagoon, temperatures, seawater pHT and dissolved oxygen chronically fluctuate between extreme and close-to-normal values (17.5–33.85 °C, 7.23–7.92 pHT units and 1.87–7.24 mg O2 L−1, respectively). In March 2020, the endosymbiont functions (chl a, cell density and photosynthesis) and respiration rates were investigated in seven coral species from this lagoon and compared with those of corals from an adjacent reference site using hour-long incubations mimicking present-day and future conditions. Corals originating from Bouraké displayed significant differences in these variables compared to reference corals, but these differences were species-specific. Photosynthetic rates of Bouraké corals were all significantly lower than those of reference corals but were partially compensated by higher chlorophyll contents. Respiration rates of the Bouraké corals were either lower or comparable to those of reference corals. Conversely, photosynthesis and respiration rates of most studied species were similar regardless of the incubation conditions, which mimicked either present-day or future conditions. This study supports previous work indicating that no unique response can explain corals’ tolerance to sub-optimal conditions and that a variety of mechanisms will be at play for corals in a changing world.
Continue reading ‘Long-term exposure to an extreme environment induces species-specific responses in corals’ photosynthesis and respiration rates’Circadian rhythm and neurotransmitters are potential pathways through which ocean acidification and warming affect the metabolism of thick-shell mussels
Published 24 March 2022 Science ClosedTags: biological response, BRcommunity, laboratory, molecular biology, mollusks, multiple factors, North Pacific, oxygen, physiology, temperature
Although the impacts of ocean acidification and warming on marine organisms have been increasingly documented, little is known about the affecting mechanism underpinning their interactive impacts on physiological processes such as metabolism. Therefore, the effects of these two stressors on metabolism were investigated in thick-shell mussel Mytilus coruscus in this study. In addition, because metabolism is primarily regulated by circadian rhythm and neurotransmitters, the impacts of acidification and warming on these two regulatory processes were also analyzed. The data obtained demonstrated that the metabolism of mussels (indicated by the clearance rate, oxygen consumption rate, ammonia excretion rate, O:N ratio, ATP content, activity of pyruvate kinase, and expression of metabolism-related genes) were significantly affected by acidification and warming, resulting in a shortage of energy supply (indicated by the in vivo content of ATP). In addition, exposure to acidification and warming led to evident disruption in circadian rhythm (indicated by the heartrate and the expression rhythm of Per2, Cry, and BMAL1) and neurotransmitters (indicated by the activity of acetyl cholinesterase and in vivo contents of ACh, GABA, and DA). These findings suggest that circadian rhythms and neurotransmitters might be potential routes through which acidification and warming interactively affect the metabolism of mussels.
Continue reading ‘Circadian rhythm and neurotransmitters are potential pathways through which ocean acidification and warming affect the metabolism of thick-shell mussels’Climate change effects on the ecophysiology and ecological functioning of an offshore wind farm artificial hard substrate community
Published 7 January 2022 Science ClosedTags: biological response, BRcommunity, cnidaria, crustaceans, laboratory, mollusks, morphology, mortality, multiple factors, oxygen, physiology, respiration, temperature
Highlights
- Local effects of offshore wind farms add to and interact with global climate change.
- Species-specific effects on artificial hard substrate colonising community.
- Mortality, feeding and metabolism generally increased with temperature and lower pH.
- Temperature and pH had antagonistic effect on growth.
- Maximised cumulative clearance potential significantly increased by climate change.
Abstract
In the effort towards a decarbonised future, the local effects of a proliferating offshore wind farm (OWF) industry add to and interact with the global effects of marine climate change. This study aimed to quantify potential ecophysiological effects of ocean warming and acidification and to estimate and compare the cumulative clearance potential of suspended food items by OWF epifauna under current and future climate conditions. To this end, this study combined ecophysiological responses to ocean warming and acidification of three dominant colonising species on OWF artificial hard substrates (the blue mussel Mytilus edulis, the tube-building amphipod Jassa herdmani and the plumose anemone Metridium senile). In general, mortality, respiration rate and clearance rate increased during 3- to 6-week experimental exposures across all three species, except for M. senile, who exhibited a lower clearance rate in the warmed treatments (+3 °C) and an insensitivity to lowered pH (−0.3 pH units) in terms of survival and respiration rate. Ocean warming and acidification affected growth antagonistically, with elevated temperature being beneficial for M. edulis and lowered pH being beneficial for M. senile. The seawater volume potentially cleared from suspended food particles by this AHS colonising community increased significantly, extending the affected distance around an OWF foundation by 9.2% in a future climate scenario. By using an experimental multi-stressor approach, this study thus demonstrates how ecophysiology underpins functional responses to climate change in these environments, highlighting for the first time the integrated, cascading potential effects of OWFs and climate change on the marine ecosystem.
Continue reading ‘Climate change effects on the ecophysiology and ecological functioning of an offshore wind farm artificial hard substrate community’Transgenerational effects decrease larval resilience to ocean acidification & warming but juvenile European sea bass could benefit from higher temperatures in the NE Atlantic
Published 29 November 2021 Science ClosedTags: biological response, fish, growth, laboratory, light, morphology, multiple factors, North Atlantic, oxygen, physiology, reproduction, respiration, temperature
The aim of this study was to investigate the effect of ocean acidification (OA) and warming (OW) as well as the transgenerational effect of OA on larval and juvenile growth and metabolism of a large economically important fish species with a long generation time. Therefore we incubated European sea bass from Brittany (France) for two generations (>5 years in total) under current and predicted OA conditions (PCO2: 650 and 1700 µatm). In the F1 generation both OA condition were crossed with OW (temperature: 15-18°C and 20-23°C). We found that OA alone did not affect larval or juvenile growth and OW increased developmental time and growth rates, but OAW decreased larval size at metamorphosis. Larval routine metabolic rate (RMR) and juvenile standard metabolic rate (SMR) were significantly lower in cold compared to warm conditioned fish and also lower in F0 compared to F1 fish. We did not find any effect of OA on RMR or SMR. Juvenile PO2crit was not affected by OA, OW or OAW in both generations.
We discuss the potential underlying mechanisms resulting in beneficial effects of OW on F1 larval growth and RMR and in resilience of F0 and F1 larvae and juveniles to OA, but on the other hand resulting in vulnerability of F1, but not F0 larvae to OAW. With regard to the ecological perspective, we conclude that recruitment of larvae and early juveniles to nursery areas might decrease under OAW conditions but individuals reaching juvenile phase might benefit from increased performance at higher temperatures.
Summary statement We found that OA did not affect developmental time, growth, RMR and SMR, while OW increased these traits. OAW decreased larval size at metamorphosis. We discuss underlying mechanisms and the ecological perspective resulting from these results and conclude that recruitment to nursery areas might decrease under OAW conditions but individuals reaching juvenile phase might benefit from increased performance at higher temperatures in Atlantic waters.
Continue reading ‘Transgenerational effects decrease larval resilience to ocean acidification & warming but juvenile European sea bass could benefit from higher temperatures in the NE Atlantic’Configuration and validation of an oceanic physical and biogeochemical model to investigate coastal eutrophication in the Southern California Bight
Published 5 November 2021 Science ClosedTags: biogeochemistry, chemistry, modeling, multiple factors, North Pacific, oxygen, primary production, regionalmodeling
Abstract
The Southern California Bight (SCB), an eastern boundary upwelling system, is impacted by global warming, acidification and oxygen loss, and receives anthropogenic nutrients from a coastal population of 20 million people. We describe the configuration, forcing, and validation of a realistic, submesoscale resolving ocean model as a tool to investigate coastal eutrophication. This modeling system represents an important achievement because it strikes a balance of capturing the forcing by U.S. Pacific Coast-wide phenomena, while representing the bathymetric features and submesoscale circulation that affect the transport of nutrients from natural and human sources. Moreover, the model allows simulations at timescales that approach the interannual frequencies of ocean variability. The model simulation is evaluated against a broad suite of observational data throughout the SCB, showing realistic depiction of the mean state and its variability with satellite and in situ measurements of state variables and biogeochemical rates. The simulation reproduces the main structure of the seasonal upwelling front, the mean current patterns, the dispersion of wastewater plumes, as well as their seasonal variability. Furthermore, it reproduces the mean distributions of key biogeochemical and ecosystem properties and their variability. Biogeochemical rates reproduced by the model, such as primary production and nitrification, are also consistent with measured rates. This validation exercise demonstrates the utility of using fine-scale resolution modeling and local observations to identify, investigate, and communicate uncertainty to stakeholders to support management decisions on local anthropogenic nutrient discharges to coastal zones.
Plain Language Summary
We applied and validated an ocean numerical model to investigate the effects of land-based and atmospheric nutrient loading on coastal eutrophication and its effects on carbon, nitrogen and oxygen cycles of the Southern California Bight, an upwelling-dominated marine embayment on the U.S. West Coast. The model is capable of high resolution, multi-year hindcast simulations, which enable investigations to disentangle natural variability, climate change, and local human pressures that accelerate land-based and atmospheric nutrient loads. The model performance assessment illustrates that it faithfully reproduces monitored ocean properties related to algal blooms, oxygen and water acidity, among others, that can be traced to land-based and atmospheric inputs of nutrients and carbon from human activities. The model performance assessment helps to constrain uncertainties in predictions to support ongoing conversations on approaches to reduce the effects of climate change, including considerations of management of local nutrient and carbon inputs.
Continue reading ‘Configuration and validation of an oceanic physical and biogeochemical model to investigate coastal eutrophication in the Southern California Bight’Brief episodes of nocturnal hypoxia and acidification reduce survival of economically important blue crab (Callinectes sapidus) larvae
Published 23 August 2021 Science ClosedTags: biological response, crustaceans, laboratory, mortality, multiple factors, oxygen, reproduction
Many shallow coastal systems experience diel fluctuations in dissolved oxygen (DO) and pH that can intensify throughout the summer season and expose estuarine organisms to repeated episodes of coastal hypoxia and acidification. In temperate regions, larval release of the economically important blue crab Callinectes sapidus occurs in the summer, and while the earliest stage (zoea I) larvae are susceptible to persistent low DO and low pH conditions, their sensitivity to diel fluctuations is unknown. Here, a series of short-term (≤96 h) experiments were conducted to investigate the survival of C. sapidus zoea I larvae exposed to a range of diel cycling hypoxic and acidified conditions and durations. Two experiments comparing a diel cycling DO/pH treatment (fluctuating from ∼30% air saturation to ∼103% averaging ∼66%/and from pH ∼7.26 to ∼7.80 averaging ∼7.53) to a static low DO/pH treatment (∼43%/∼7.35), a static moderate DO/pH treatment (∼68%/∼7.59), and a static control treatment (∼106%/∼7.94) indicated that survival in the diel cycling treatment was significantly lower than the moderate treatment (p < 0.05) by 75 and 48% over 96 and 48 h, respectively, despite comparable mean experimental DO/pH values. Three other experiments aimed at identifying the effective minimum duration of low DO/low pH to significantly depress larval survival under diel cycling conditions revealed that 8 h of low DO/low pH (∼28%/∼7.43) over a 24-h diel cycle consistently decreased survival (p < 0.05) relative to control conditions by at least 55% regardless of experimental duration (72-, 48-, and 24-h experiments). An increase in DO beyond saturation to supersaturation (160%) and pH beyond normocapnic to highly basified (8.34) conditions during the day phase of the diel cycle did not improve survival of larvae exposed to nocturnal hypoxia and acidification. Collectively, these experiments demonstrate that diel cycling does not provide newly hatched C. sapidus larvae a temporal refuge capable of ameliorating low DO/pH stress, but rather is more lethal than chronic exposure to comparable average DO/pH conditions. Given that larvae exposed to a single nocturnal episode of moderate hypoxia and acidification experience significantly reduced survival, such occurrences may depress larval recruitment.
Continue reading ‘Brief episodes of nocturnal hypoxia and acidification reduce survival of economically important blue crab (Callinectes sapidus) larvae’
