Posts Tagged 'review'

Seasonality and life history complexity determine vulnerability of Dungeness crab to multiple climate stressors

Abstract

Scaling climate change impacts from individual responses to population-level vulnerability is a pressing challenge for scientists and society. We assessed vulnerability of the most valuable fished species in the Northwest U.S.—Dungeness crab—to climate stressors using a novel combination of ocean, population, and larval transport models with stage-specific consequences of ocean acidification, hypoxia, and warming. Integration across pelagic and benthic life stages revealed increased population-level vulnerability to each stressor by 2100 under RCP 8.5. Under future conditions, chronic vulnerability to low pH emerged year-round for all life stages, whereas vulnerability to low oxygen continued to be acute, developing seasonally and impacting adults, which are critical to population growth. Our results demonstrate how ontogenetic habitat shifts and seasonal ocean conditions interactively impact population-level vulnerability. Because most valuable U.S. fisheries rely on species with complex life cycles in seasonal seas, chronic and acute perspectives are necessary to assess population-level vulnerability to climate change.

Plain Language Summary

The release of carbon dioxide (CO2) into the atmosphere by human activities is altering ocean conditions including pH, oxygen, and temperature. One way to understand how these changing conditions will affect ecologically, economically, and culturally important marine species is to scale individual responses from laboratory experiments to population-level impacts. In this study, we assessed the vulnerability of Dungeness crab, one of the most valuable fisheries in the NW USA, to stressful conditions based on the predicted habitat exposure and response of each life stage (eggs, larvae, juveniles, and adults). The degree of vulnerability was determined by the seasonality of the ocean conditions in combination with the crab’s complex life cycle. This approach revealed that Dungeness crab life stages and populations will be more vulnerable to low pH, low oxygen, and high temperature in the future (year 2100) under an aggressive CO2 emissions scenario. Based on these results, we recommend that fishery managers incorporate changing conditions into their decision-making to protect vulnerable life stages in areas prone to stressful conditions (e.g., adult crabs in hypoxic areas). Our approach can be adapted for many other economically and ecologically important marine species in order to inform conservation and management strategies.

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Possible future scenarios for two major Arctic Gateways connecting Subarctic and Arctic marine systems: I. climate and physical–chemical oceanography

We review recent trends and projected future physical and chemical changes under climate change in transition zones between Arctic and Subarctic regions with a focus on the two major inflow gateways to the Arctic, one in the Pacific (i.e. Bering Sea, Bering Strait, and the Chukchi Sea) and the other in the Atlantic (i.e. Fram Strait and the Barents Sea). Sea-ice coverage in the gateways has been disappearing during the last few decades. Projected higher air and sea temperatures in these gateways in the future will further reduce sea ice, and cause its later formation and earlier retreat. An intensification of the hydrological cycle will result in less snow, more rain, and increased river runoff. Ocean temperatures are projected to increase, leading to higher heat fluxes through the gateways. Increased upwelling at the Arctic continental shelf is expected as sea ice retreats. The pH of the water will decline as more atmospheric CO2 is absorbed. Long-term surface nutrient levels in the gateways will likely decrease due to increased stratification and reduced vertical mixing. Some effects of these environmental changes on humans in Arctic coastal communities are also presented.

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Co‑occurrence of aquatic heatwaves with atmospheric heatwaves, low dissolved oxygen, and low pH events in estuarine ecosystems

Heatwaves are increasing in frequency, duration, and intensity in the atmosphere and marine environment with rapid changes to ecosystems occurring as a result. However, heatwaves in estuarine ecosystems have received little attention despite the effects of high temperatures on biogeochemical cycling and fisheries and the susceptibility of estuaries to heatwaves given their low volume. Likewise, estuarine heatwave co-occurrence with extremes in water quality variables such as dissolved oxygen (DO) and pH have not been considered and would represent periods of enhanced stress. This study analyzed 1440 station years of high-frequency data from the National Estuarine Research Reserve System (NERRS) to assess trends in the frequency, duration, and severity of estuarine heatwaves and their co-occurrences with atmospheric heatwaves, low DO, and low pH events between 1996 and 2019. Estuaries are warming faster than the open and coastal ocean, with an estuarine heatwave mean annual occurrence of 2 ± 2 events, ranging up to 10 events per year, and lasting up to 44 days (mean duration = 8 days). Estuarine heatwaves co-occur with an atmospheric heatwave 6–71% of the time, depending on location, with an average estuarine heatwave lag range of 0–2 days. Similarly, low DO or low pH events co-occur with an estuarine heatwave 2–45% and 0–18% of the time, respectively, with an average low DO lag of 3 ± 2 days and low pH lag of 4 ± 2 days. Triple co-occurrence of an estuarine heatwave with a low DO and low pH event was rare, ranging between 0 and 7% of all estuarine heatwaves. Amongst all the stations, there have been significant reductions in the frequency, intensity, duration, and rate of low DO event onset and decline over time. Likewise, low pH events have decreased in frequency, duration, and intensity over the study period, driven in part by reductions in all severity classifications of low pH events. This study provides the first baseline assessment of estuarine heatwave events and their co-occurrence with deleterious water quality conditions for a large set of estuaries distributed throughout the USA.

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Effects of ocean acidification on marine primary producers and related ecological processes under multiple stressors

Although the individual effects of ocean acidification (OA), warming, solar UV radiation, deoxygenation and heavy metal pollution on marine producers are well-studied, their interactive effects are still unclear, strongly limiting our ability to project the ecological consequences of ocean climate changes. This chapter aims to provide an overview of our understanding the eco-physiological effects of OA and its combination with warming, solar UV radiation, deoxygenation and heavy metals. While OA is known to enhance photorespiration in both diatoms and green macroalgae, it enhances growth of coastal diatoms and other macroalgae that are adapted to fluctuating diel pH changes and then potentially enhances its contribution to carbon sequestration in coastal waters. OA is supposed to decrease pelagic primary productivity under multiple stressors (e.g., in combination with ultraviolet radiation, deoxygenation, warming), especially in oligotrophic waters, due to insufficient repairing or improvising processes that require both macro- and trace nutrients for syntheses of required proteins. Under influences of OA, macroalgal communities would shift toward non-calcifying species; diatoms become less abundance in phytoplankton assemblages. OA decreases calcification in algal calcifiers and exposes them to more harmful UV radiation, leading to a further decline of photosynthesis. Therefore, both the magnitude and direction of response of microalgae and macroalgae to OA largely depend on the levels of other environmental drivers (e.g., warming, deoxygenation). OA also exerts tremendous impacts on marine food webs. Total fatty acids and the ratio of long-chain polyunsaturated to saturated fatty acids of microalgae decrease, while some toxic secondary metabolites (such as phenolic compounds) accumulate under OA conditions, indicating a decline of food quality. This decline of food quality in primary producers can be transferred to secondary producers and negatively affect them (e.g., decrease in growth and reproduction). Taken together, OA can influence the biochemical compositions and contents in primary producers and their transfer to higher trophic levels and marine food webs is likely to be destabilized.

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Elasmobranch responses to experimental warming, acidification, and oxygen loss—a meta-analysis

Despite the long evolutionary history of this group, the challenges brought by the Anthropocene have been inflicting an extensive pressure over sharks and their relatives. Over exploitation has been driving a worldwide decline in elasmobranch populations, and rapid environmental change, triggered by anthropogenic activities, may further test this group’s resilience. In this context, we searched the literature for peer-reviewed studies featuring a sustained (>24 h) and controlled exposure of elasmobranch species to warming, acidification, and/or deoxygenation: three of the most pressing symptoms of change in the ocean. In a standardized comparative framework, we conducted an array of mixed-model meta-analyses (based on 368 control-treatment contrasts from 53 studies) to evaluate the effects of these factors and their combination as experimental treatments. We further compared these effects across different attributes (lineages, climates, lifestyles, reproductive modes, and life stages) and assessed the direction of impact over a comprehensive set of biological responses (survival, development, growth, aerobic metabolism, anaerobic metabolism, oxygen transport, feeding, behavior, acid-base status, thermal tolerance, hypoxia tolerance, and cell stress). Based on the present findings, warming appears as the most influential factor, with clear directional effects, namely decreasing development time and increasing aerobic metabolism, feeding, and thermal tolerance. While warming influence was pervasive across attributes, acidification effects appear to be more context-specific, with no perceivable directional trends across biological responses apart from the necessary to achieve acid-base balance. Meanwhile, despite its potential for steep impacts, deoxygenation has been the most neglected factor, with data paucity ultimately precluding sound conclusions. Likewise, the implementation of multi-factor treatments has been mostly restricted to the combination of warming and acidification, with effects approximately matching those of warming. Despite considerable progress over recent years, research regarding the impact of these drivers on elasmobranchs lags behind other taxa, with more research required to disentangle many of the observed effects. Given the current levels of extinction risk and the quick pace of global change, it is further crucial that we integrate the knowledge accumulated through different scientific approaches into a holistic perspective to better understand how this group may fare in a changing ocean.

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Species’ distribution and evolutionary history influence the responses of marine copepods to climate change: a global meta-analysis

Ocean acidification (OA) and ocean warming (OW) are predicted to drive changes to the distribution of species and the structure of biological communities globally. Differences in life-history, physical traits, and the phenotypic response of organisms will, however, mean that the effects of OA and OW will differ among species. Geographical differences in environmental characteristics across habitats will also influence the effects of OA and OW, thereby driving inter-population differences in phenotypic response as determined by local adaptations. While is it accepted that the response of species will vary globally, predicting the trends in response of species remains highly uncertain. We undertook a meta-analysis of key biological traits of 47 marine copepod species from 88 studies to identify the intrinsic and extrinsic factors influencing the effects of OA and OW on copepod population demographics. Data from OA and OW were analysed independently due to insufficient two-stressor studies. We found that the large disparity in the response of species to OA and OW is largely defined by their environmental history. Additionally, the response of copepod species to OW is related to their evolutionary history which has less influence on their response to OA. Therefore, our study identified that the response of copepods to OA is driven by a combination of biotic and abiotic factors in their habitats. Under OA alone, copepods from less variable environments may be more susceptible, but the effects of OA will only be strongly negative at extreme low pH (<7). On the other hand, the response to OW is deeply tied to their phylogeny, whereby closely related species share similar costs and trade-offs. However, the effects of near-future OW (+2 to 4°C) seem mainly positive unless these temperatures exceed a species’ thermal limit. Finally, our analysis revealed that OW has a greater influence on key copepod traits than OA. Overall, this study shows that attempting to draw global patterns in the response of species to climate change from a single species or habitat without consideration of environmental and evolutionary history could lead to inaccurate and misleading predictions with respect to the future of biological communities.

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Impacts of marine heatwaves on algal structure and carbon sequestration in conjunction with ocean warming and acidification

As the ocean warms, the frequency, duration, intensity, and range of marine heatwaves (MHWs) increase. MHWs are becoming a severe challenge for marine ecosystems. However, our understanding in regard to their impacts on algal structure and carbon sequestration is still deficient or fragmentary, particularly when combined with ocean warming and acidification. In this paper, we reviewed the impacts of MHWs individually and combined with ocean warming and acidification on regime shift in algal community and carbon sequestration of both macroalgae and microalgae. Solid evidence shows that MHWs cause the decline of large canopy macroalgae and increase of turf-forming macroalgae in abundance, leading to the regime shift from kelp forests to seaweed turfs. Furthermore, increased grazing pressure on kelps due to tropicalization facilitates the expansion of turfs that prevent the recovery of kelps through plundering light and space. Meanwhile, MHWs could trigger microalgal blooms and the intensity of algal blooms is regulated by the severity of MHWs and nutrient availability. MHWs could lead to the decrease of carbon burial and sequestration by canopy-forming macroalgae due to depressed growth and increased mortality. The effects of MHWs on the productivity of microalgae are latitude-dependent: negative effects at low and mid-latitudes whilst positive effects at high latitudes. Ocean warming and acidification may accelerate the shift from kelps to turfs and thus decrease the carbon sequestration by canopy-forming macroalgae further. We propose that MHWs combined with ocean warming and acidification would reduce the biodiversity and facilitate the thriving of morphologically simple, ephemeral and opportunistic turfs and diatoms in coastal oceans, and phytoplankton with smaller size in open oceans. This structure shift would not be in favor of long-term carbon sequestration. Future studies could be conducted to test this hypothesis and investigate the impacts of MHWs on carbon sequestration under future ocean conditions.

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Editorial: fitness of marine calcifiers in the future acidifying ocean

Over the last century, anthropogenic CO2 emissions via combustion of fossil fuels have caused drastic changes in oceans with sea surface temperatures increasing steadily due to global warming. In addition to ocean warming, seawater has become more acidic as more CO2 is dissolved into the world’s oceans (IPCC, 2019). As CO2 emissions are forecast to accelerate in the future (Caldeira and Wickett, 2005), understanding how marine organisms are influenced by ocean acidification (OA) and warming has received substantial attention (Doney et al., 2009). Organisms which build calcareous structures for growth and protection (e.g., coccolithophores, corals, gastropods, bivalves, and sea urchins) are of particular concern because OA is expected to make calcification more energy-demanding and increase dissolution of calcareous structures (Harvey et al., 2018Byrne and Fitzer, 2019). Consequently, the fitness and survival of marine calcifiers could be reduced, possibly affecting the integrity of marine ecosystems in view of their abundance, diversity, and ecological functions in oceans.

There is now a large body of literature which demonstrates that calcifiers can indeed be impaired by OA in various aspects, such as physiology, calcification, growth, and survival (Harvey et al., 2013). Nevertheless, growing evidence reveals that some calcifiers can prevail in the CO2-acidified environment and produce durable calcareous structures (e.g., Leung et al., 20192020aDi Giglio et al., 2020), implying their resistance and adaptability to OA. Thus, more comprehensive studies are needed to decipher how calcifiers adjust or succumb to OA and how warming modulates the impacts of OA on calcifiers. We brought together this Research Topic to address these issues and provide better insights into the fate of calcifiers in future marine ecosystems.

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Biotic habitats as refugia under ocean acidification

Habitat-forming organisms have an important role in ameliorating stressful conditions and may be of particular relevance under a changing climate. Increasing CO2 emissions are driving a range of environmental changes, and one of the key concerns is the rapid acceleration of ocean acidification and associated reduction in pH. Such changes in seawater chemistry are anticipated to have direct negative effects on calcifying organisms, which could, in turn, have negative ecological, economic and human health impacts. However, these calcifying organisms do not exist in isolation, but rather are part of complex ecosystems. Here, we use a qualitative narrative synthesis framework to explore (i) how habitat-forming organisms can act to restrict environmental stress, both now and in the future; (ii) the ways their capacity to do so is modified by local context; and (iii) their potential to buffer the effects of future change through physiological processes and how this can be influenced by management adopted. Specifically, we highlight examples that consider the ability of macroalgae and seagrasses to alter water carbonate chemistry, influence resident organisms under current conditions and their capacity to do so under future conditions, while also recognizing the potential role of other habitats such as adjacent mangroves and saltmarshes. Importantly, we note that the outcome of interactions between these functional groups will be context dependent, influenced by the local abiotic and biotic characteristics. This dependence provides local managers with opportunities to create conditions that enhance the likelihood of successful amelioration. Where individuals and populations are managed effectively, habitat formers could provide local refugia for resident organisms of ecological and economic importance under an acidifying ocean.

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Advances in ocean acidification

Ocean acidification is the ongoing decrease in the pH of the Earth’s oceans, caused by the uptake of carbon dioxide (CO2 from the atmosphere. The main cause of ocean acidification is the burning of fossil fuels. Seawater is slightly basic (meaning pH > 7), and ocean acidification involves a shift towards pH-neutral conditions rather than a transition to acidic conditions (pH < 7). The issue of ocean acidification is the decreased production of the shells of shellfish and other aquatic life with calcium carbonate shells. The calcium carbonate shells can not reproduce under high saturated acidotic waters. An estimated 30–40% of the carbon dioxide from human activity released into the atmosphere dissolves into oceans, rivers and lakes. Some of it reacts with the water to form carbonic acid. Some of the resulting carbonic acid molecules dissociate into a bicarbonate ion and a hydrogen ion, thus increasing ocean acidity (H+ ion concentration). Between 1751 and 1996, surface ocean pH is estimated to have decreased from approximately 8.25 to 8.14, representing an increase of almost 30% in H+ ion concentration in the world’s oceans. Earth System Models project that, by around 2008, ocean acidity exceeded historical analoguesand, in combination with other ocean biogeochemical changes, could undermine the functioning of marine ecosystems and disrupt the provision of many goods and services associated with the ocean beginning as early as 2100.

In the present book, fifteen typical literatures about ocean acidification published on international authoritative journals were selected to introduce the worldwide newest progress, which contains reviews or original researches on ocean acidification. We hope this book can demonstrate advances in ocean acidification as well as give references to the researchers, students and other related people.

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How have reductions in global carbon dioxide emissions during the COVID-19 pandemic influenced aquatic ecosystems through ocean acidification?

The effects from the COVID-19 pandemic have resulted in the largest annual decrease in global carbon dioxide (CO2) emissions based on countries with the highest industrial output, including China, the United States, India, and the European Union, as well as the global oil sector [12]. With lockdowns and stay-at-home orders being implemented in the vast majority of the world, the overall production decreased by 8.8% in the first half of 2020 alone [12].

In regards to these emissions, the anthropogenic greenhouse effect – the gradual, incessant warming of the Earth’s surface due to human-related greenhouse gas emissions, including land use change and fossil fuel burning – is oftentimes the first pertinent concern [6]. However, ocean acidification is also a relevant, yet overlooked secondary concern that is directly related to atmospheric CO2 levels. Oceans are a crucial element in offsetting the anthropogenic greenhouse effect; they are natural carbon sinks, or reservoirs, that uptake CO2 in the form of dissolved inorganic carbon (DIC), enable its conversion to dissolved organic carbon (DOC) through chemical processes, and sequester this carbon to the deep ocean where it can persist for thousands of years out of Earth’s atmosphere [1].

Increased anthropogenic CO2 results in increased pressure placed on oceans to absorb more atmospheric CO2 [1]. This ultimately favours a decrease in carbonate ions and a net increase in protons, which decreases the pH of oceans, making them more acidic [8]. Acidifying oceans have cascading effects on aquatic organisms and, eventually as the effects reach higher trophic levels, humans.

Although it is known that CO2 emissions have been altered during the global pandemic,the effects in regards to ocean acidification are largely understudied. This paper evaluates how the effects from COVID-19 have changed ocean acidification trends and, consequently, the impact on aquatic ecosystems. Future approaches and limitations in monitoring ocean acidification and aquatic ecosystem health are also discussed.

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Impact of polycyclic aromatic hydrocarbon accumulation on oyster health

In the past decade, the Deepwater Horizon oil spill triggered a spike in investigatory effort on the effects of crude oil chemicals, most notably polycyclic aromatic hydrocarbons (PAHs), on marine organisms and ecosystems. Oysters, susceptible to both waterborne and sediment-bound contaminants due to their filter-feeding and sessile nature, have become of great interest among scientists as both a bioindicator and model organism for research on environmental stressors. It has been shown in many parts of the world that PAHs readily bioaccumulate in the soft tissues of oysters. Subsequent experiments have highlighted the negative effects associated with exposure to PAHs including the upregulation of antioxidant and detoxifying gene transcripts and enzyme activities such as Superoxide dismutase, Cytochrome P450 enzymes, and Glutathione S-transferase, reduction in DNA integrity, increased infection prevalence, and reduced and abnormal larval growth. Much of these effects could be attributed to either oxidative damage, or a reallocation of energy away from critical biological processes such as reproduction and calcification toward health maintenance. Additional abiotic stressors including increased temperature, reduced salinity, and reduced pH may change how the oyster responds to environmental contaminants and may compound the negative effects of PAH exposure. The negative effects of acidification and longer-term salinity changes appear to add onto that of PAH toxicity, while shorter-term salinity changes may induce mechanisms that reduce PAH exposure. Elevated temperatures, on the other hand, cause such large physiological effects on their own that additional PAH exposure either fails to cause any significant effects or that the effects have little discernable pattern. In this review, the oyster is recognized as a model organism for the study of negative anthropogenic impacts on the environment, and the effects of various environmental stressors on the oyster model are compared, while synergistic effects of these stressors to PAH exposure are considered. Lastly, the understudied effects of PAH photo-toxicity on oysters reveals drastic increases to the toxicity of PAHs via photooxidation and the formation of quinones. The consequences of the interaction between local and global environmental stressors thus provide a glimpse into the differential response to anthropogenic impacts across regions of the world.

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Coralporosis: ocean acidification leaves deep-sea coral reefs at risk of collapse

As we age, our skeletons often become riddled with osteoporosis, a disease in which the body loses too much bone. As a result, our hips and wrists become weak and may break. Could the same thing happen to the skeletons of coral reefs? Recent research says yes, and points to a weakening of deep-sea corals’ “bones” from ocean acidification.

The study, which advances efforts to understand how reefs of the future will look and what we can do to preserve them and the life they support, was published in Frontiers of Marine Science in September 2020. It was led by University of Edinburgh scientists, along with researchers from Heriot-Watt University and the US National Oceanic and Atmospheric Administration (NOAA) and was supported by the European Union’s Horizon 2020 Research and Innovation Programme and several other funders.

“Ocean acidification is a threat to the net growth of tropical and deep-sea coral reefs due to gradual changes in the balance between reef growth and loss processes,” write lead author Sebastian Hennige of the University of Edinburgh’s School of GeoSciences and his coauthors. “We go beyond identification of coral dissolution induced by ocean acidification to identify a mechanism that will lead to the loss of habitat in cold-water coral reef habitats on an ecosystem scale.” 

Lophelia pertusa coral in corrosive waters off Southern California Bight. Live coral is on exposed rock with no dead coral framework. Image credit: NOAA.
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Evolution and biomineralization of pteropod shells

Highlights

  • Pteropod shells harbor a striking diversity of microstructures.
  • Curved aragonite fibres are found in both superfamilies: Limacinoidea (coiled) and Cavolinioidea (uncoiled).
  • Different levels of complexity of the helical microstructure exist: from incomplete to multiple helical turns.
  • Microstructural observations in the fossil record suggest that the emergence of curved fibres precedes the diversification of euthecosomatous pteropods.
  • Candidate biomineralization genes are identified based on shell matrix proteins from benthic and terrestrial snails.

Abstract

Shelled pteropods, known as ‘sea butterflies’, are a group of small gastropods that spend their entire lives swimming and drifting in the open ocean. They build thin shells of aragonite, a metastable polymorph of calcium carbonate. Pteropod shells have been shown to experience dissolution and reduced thickness with a decrease in pH and therefore represent valuable bioindicators to monitor the impacts of ocean acidification. Over the past decades, several studies have highlighted the striking diversity of shell microstructures in pteropods, with exceptional mechanical properties, but their evolution and future in acidified waters remains uncertain. Here, we revisit the body-of-work on pteropod biomineralization, focusing on shell microstructures and their evolution. The evolutionary history of pteropods was recently resolved, and thus it is timely to examine their shell microstructures in such context. We analyse new images of shells from fossils and recent species providing a comprehensive overview of their structural diversity. Pteropod shells are made of the crossed lamellar and prismatic microstructures common in molluscs, but also of curved nanofibers which are proposed to form a helical three-dimensional structure. Our analyses suggest that the curved fibres emerged before the split between coiled and uncoiled pteropods and that they form incomplete to multiple helical turns. The curved fibres are seen as an important trait in the adaptation to a planktonic lifestyle, giving maximum strength and flexibility to the pteropod thin and lightweight shells. Finally, we also elucidate on the candidate biomineralization genes underpinning the shell diversity in these important indicators of ocean health.

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The role of a changing Arctic Ocean and climate for the biogeochemical cycling of dimethyl sulphide and carbon monoxide

Dimethyl sulphide (DMS) and carbon monoxide (CO) are climate-relevant trace gases that play key roles in the radiative budget of the Arctic atmosphere. Under global warming, Arctic sea ice retreats at an unprecedented rate, altering light penetration and biological communities, and potentially affect DMS and CO cycling in the Arctic Ocean. This could have socio-economic implications in and beyond the Arctic region. However, little is known about CO production pathways and emissions in this region and the future development of DMS and CO cycling. Here we summarize the current understanding and assess potential future changes of DMS and CO cycling in relation to changes in sea ice coverage, light penetration, bacterial and microalgal communities, pH and physical properties. We suggest that production of DMS and CO might increase with ice melting, increasing light availability and shifting phytoplankton community. Among others, policy measures should facilitate large-scale process studies, coordinated long term observations and modelling efforts to improve our current understanding of the cycling and emissions of DMS and CO in the Arctic Ocean and of global consequences.

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Environmental risk of nickel in aquatic Arctic ecosystems

Highlights

  • Elevated concentrations of Ni occur near mining/smelting operations in the Arctic
  • There is a lack of Ni exposure scenarios in coastal, estuarine, and marine waters.
  • Freshwater Ni bioavailability follows spatial trends in dissolved organic carbon.
  • A critical gap to Ni risk assessment is a lack of toxicity data with Arctic species.
  • Climate change will affect Ni exposure and may influence its effects in the Arctic.

Abstract

The Arctic faces many environmental challenges, including the continued exploitation of its mineral resources such as nickel (Ni). The responsible development of Ni mining in the Arctic requires establishing a risk assessment framework that accounts for the specificities of this unique region. We set out to conduct preliminary assessments of Ni exposure and effects in aquatic Arctic ecosystems. Our analysis of Ni source and transport processes in the Arctic suggests that fresh, estuarine, coastal, and marine waters are potential Ni-receiving environments, with both pelagic and benthic communities being at risk of exposure. Environmental concentrations of Ni show that sites with elevated Ni concentrations are located near Ni mining operations in freshwater environments, but there is a lack of data for coastal and estuarine environments near such operations. Nickel bioavailability in Arctic freshwaters seems to be mainly driven by dissolved organic carbon (DOC) concentrations with bioavailability being the highest in the High Arctic, where DOC levels are the lowest. However, this assessment is based on bioavailability models developed from non-Arctic species. At present, the lack of chronic Ni toxicity data on Arctic species constitutes the greatest hurdle toward the development of Ni quality standards in this region. Although there are some indications that polar organisms may not be more sensitive to contaminants than non-Arctic species, biological adaptations necessary for life in polar environments may have led to differences in species sensitivities, and this must be addressed in risk assessment frameworks. Finally, Ni polar risk assessment is further complicated by climate change, which affects the Arctic at a faster rate than the rest of the world. Herein we discuss the source, fate, and toxicity of Ni in Arctic aquatic environments, and discuss how climate change effects (e.g., permafrost thawing, increased precipitation, and warming) will influence risk assessments of Ni in the Arctic.

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A review of sustainability concepts in marine spatial planning and the potential to supporting the UN sustainable development goal 14

Ecosystems all over the world are under increasing pressure from human uses. The UN Sustainable Development Goal 14 (UN SDG 14) seeks to ensure sustainability below water by 2020; however, the ongoing biodiversity loss and habitat deterioration challenge the achievement of this goal. Marine Spatial Planning (MSP) is a developing practice with a similar objective to the UN SDG 14, albeit research shows that most MSP cases prioritize economic objectives above environmental objectives. This paper presents an assessment of how MSP can contribute to achieving the UN SDG 14. Results are presented in three steps. First, a representative definition of MSP is presented. Secondly, activities that can be addressed through MSP are laid out. Lastly, results are used to assess how MSP can contribute to the achievement of the UN SDG 14 targets and indicators. This assessment shows great potential for MSP to play a role in the achievement of the UN SDG 14.

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Another decade of marine climate change experiments: trends, progress and knowledge gaps

Anthropogenic climate change is a significant driver of change in marine ecosystems globally. To improve mechanistic understanding of the impact of climate-related stressors, experimental work on marine organisms has intensified in recent decades. A previous synthesis paper published nearly a decade ago established that Marine Climate Change Experiments (MCCEs) published from 2000–2009 were primarily laboratory-based and focused on single stressors and individual focal temperate species. Using consistent methodology, we compared the 2000–2009 analysis to experiments published in the following decade (i.e. 2010–2019) to assess recent trends in MCCEs and to determine to what extent knowledge gaps and research priorities have been addressed. The search returned 854 papers, vs. 110 from the 2000s, indicating considerable intensification of research effort and output. We found again that single species studies were most common, particularly with benthic invertebrates as model organisms, and that laboratory-based research comprised over 90% of all studies. However, multiple stressor experiments increased substantially, where tests for interaction effects between ocean acidification (i.e., increased pCO2) and warming were particularly common. Furthermore, a wider range of model species were studied and more community-level experiments were conducted in the 2010s compared with the 2000s. In addition, studies on behavioral responses, transgenerational effects, genetic adaptation and extreme climatic events increased markedly. These recent advances in MCCEs have undoubtedly improved understanding of how climate change will affect marine organisms and the communities and ecosystems they underpin. Going forward, biases in the type and distribution of model organisms should be addressed to enhance general understanding of responses to environmental change. Similarly, experiments should manipulate a greater number and range of climate and non-climate factors and increase the number of target organisms to increase realism. Finally, where possible, further research should be combined and contextualized with field-based experiments and observations to better reflect the complexity of marine ecosystems and yield more representative responses to ocean climate change.

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The enzymology of ocean global change

A small subset of marine microbial enzymes and surface transporters have a disproportionately important influence on the cycling of carbon and nutrients in the global ocean. As a result, they largely determine marine biological productivity and have been the focus of considerable research attention from microbial oceanographers. Like all biological catalysts, the activity of these keystone biomolecules is subject to control by temperature and pH, leaving the crucial ecosystem functions they support potentially vulnerable to anthropogenic environmental change. We summarize and discuss both consensus and conflicting evidence on the effects of sea surface warming and ocean acidification for five of these critical enzymes [carbonic anhydrase, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), nitrogenase, nitrate reductase, and ammonia monooxygenase] and one important transporter (proteorhodopsin). Finally, we forecast how the responses of these few but essential biocatalysts to ongoing global change processes may ultimately help to shape the microbial communities and biogeochemical cycles of the future greenhouse ocean.

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Combined effects of ocean warming and acidification on marine fish and shellfish: a molecule to ecosystem perspective

Highlights

  • Climate change would have profound repercussion on fisheries sector
  • Multiple interactive stressors can incapacitate biological functioning.
  • Trophic pyramids and food web architecture studies need to be approached.
  • Combined in situ monitoring and laboratory studies should be prioritized.

Abstract

It is expected that by 2050 human population will exceed nine billion leading to increased pressure on marine ecosystems. Therefore, it is conjectured various levels of ecosystem functioning starting from individual to population-level, species distribution, food webs and trophic interaction dynamics will be severely jeopardized in coming decades. Ocean warming and acidification are two prime threats to marine biota, yet studies about their cumulative effect on marine fish and shellfishes are still in its infancy. This review assesses existing information regarding the interactive effects of global environmental factors like warming and acidification in the perspective of marine capture fisheries and aquaculture industry. As climate change continues, distribution pattern of species is likely to be altered which will impact fisheries and fishing patterns. Our work is an attempt to compile the existing literatures in the biological perspective of the above-mentioned stressors and accentuate a clear outline of knowledge in this subject. We reviewed studies deciphering the biological consequences of warming and acidification on fish and shellfishes in the light of a molecule to ecosystem perspective. Here, for the first time impacts of these two global environmental drivers are discussed in a holistic manner taking into account growth, survival, behavioural response, prey predator dynamics, calcification, biomineralization, reproduction, physiology, thermal tolerance, molecular level responses as well as immune system and disease susceptibility. We suggest urgent focus on more robust, long term, comprehensive and ecologically realistic studies that will significantly contribute to the understanding of organism’s response to climate change for sustainable capture fisheries and aquaculture.

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