Posts Tagged 'review'

Role of technology in ocean acidification: monitoring, water-quality impairments, CO2 mitigation, and machine learning

Ocean acidification (OA), or the reduction in the pH of the ocean, is driven by increasing carbon dioxide concentration in the atmosphere and local pollution. There is already evidence of the detrimental impact of OA on marine organisms. As further increases in atmospheric CO2 and changes in water quality are expected, it is crucial to develop and implement advanced technologies that enable better monitoring, allow for understanding of adaptation potential of the organisms, and facilitate the use of mitigation strategies toward predicted environmental changes. Collaboration of marine and computer scientists, engineers, and citizens is needed to develop innovative sustainable technologies to mitigate and reduce future increase of CO2.

Continue reading ‘Role of technology in ocean acidification: monitoring, water-quality impairments, CO2 mitigation, and machine learning’

Reviews and syntheses: revisiting the boron systematics of aragonite and their application to coral calcification (update)

The isotopic and elemental systematics of boron in aragonitic coral skeletons have recently been developed as a proxy for the carbonate chemistry of the coral extracellular calcifying fluid. With knowledge of the boron isotopic fractionation in seawater and the B∕Ca partition coefficient (KD) between aragonite and seawater, measurements of coral skeleton δ11B and B∕Ca can potentially constrain the full carbonate system. Two sets of abiogenic aragonite precipitation experiments designed to quantify KD have recently made possible the application of this proxy system. However, while different KD formulations have been proposed, there has not yet been a comprehensive analysis that considers both experimental datasets and explores the implications for interpreting coral skeletons. Here, we evaluate four potential KD formulations: three previously presented in the literature and one newly developed. We assess how well each formulation reconstructs the known fluid carbonate chemistry from the abiogenic experiments, and we evaluate the implications for deriving the carbonate chemistry of coral calcifying fluid. Three of the KD formulations performed similarly when applied to abiogenic aragonites precipitated from seawater and to coral skeletons. Critically, we find that some uncertainty remains in understanding the mechanism of boron elemental partitioning between aragonite and seawater, and addressing this question should be a target of additional abiogenic precipitation experiments. Despite this, boron systematics can already be applied to quantify the coral calcifying fluid carbonate system, although uncertainties associated with the proxy system should be carefully considered for each application. Finally, we present a user-friendly computer code that calculates coral calcifying fluid carbonate chemistry, including propagation of uncertainties, given inputs of boron systematics measured in coral skeleton.

Continue reading ‘Reviews and syntheses: revisiting the boron systematics of aragonite and their application to coral calcification (update)’

Ocean connections: an introduction to rising risks from a warming, changing ocean

Ocean risk: the challenges a warming, changing ocean presents to humanity and life on earth.

The ocean on which Earth depends for relatively predictable weather, temperature and provisioning of goods and services is now changing more rapidly than it has for millions of years. This is due to human interactions with the atmosphere and land, and increasing expansion of the footprint of human impacts across the ocean. It is increasingly evident that patterns and trends in ocean and atmospheric responses are falling outside documented historical norms. Continue reading ‘Ocean connections: an introduction to rising risks from a warming, changing ocean’

A review on the biodiversity, distribution and trophic role of cephalopods in the Arctic and Antarctic marine ecosystems under a changing ocean

Cephalopods play an important role in polar marine ecosystems. In this review, we compare the biodiversity, distribution and trophic role of cephalopods in the Arctic and in the Antarctic. Thirty-two species have been reported from the Arctic, 62 if the Pacific Subarctic is included, with only two species distributed across both these Arctic areas. In comparison, 54 species are known from the Antarctic. These polar regions share 15 families and 13 genera of cephalopods, with the giant squid Architeuthis dux the only species confirmed to occur in both the Arctic and Antarctic. Polar cephalopods prey on crustaceans, fish, and other cephalopods (including cannibalism), whereas predators include fish, other cephalopods, seabirds, seals and whales. In terms of differences between the cephalopod predators in the polar regions, more Antarctic seabird species feed on cephalopods than Arctic seabirds species, whereas more Arctic mammal species feed on cephalopods than Antarctic mammal species. Cephalopods from these regions are likely to be more influenced by climate change than those from the rest of the World: Arctic fauna is more subjected to increasing temperatures per se, with these changes leading to increased species ranges and probably abundance. Antarctic species are likely to be influenced by changes in (1) mesoscale oceanography (2) the position of oceanic fronts (3) sea ice extent, and (4) ocean acidification. Polar cephalopods may have the capacity to adapt to changes in their environment, but more studies are required on taxonomy, distribution, ocean acidification and ecology.

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Harmful algal blooms in a changing ocean

There is emerging evidence that climate change already may be causing shifts in the composition of coastal and offshore marine plankton and benthic communities, and there is reasonable expectation that future climate scenario’s will lead to changes in the spatial and temporal ranges of HAB species. The concern is that these changes may increase the frequency and severity of harmful algal blooms (HABs), which can be broadly categorized as toxin-produced or high- “biomass” events.

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Living in a high CO2 world: a global meta‐analysis shows multiple trait‐mediated fish responses to ocean acidification

Understanding how marine organisms will be affected by global change is of primary importance to ensure ecosystem functioning and nature contributions to people. This study meets the call for addressing how life‐history traits mediate effects of ocean acidification on fish. We built a database of overall and trait‐mediated responses of teleost fish to future CO2 levels by searching the scientific literature. Using a meta‐analytical approach, we investigated the effects of projected CO2 levels by IPCC for 2050–2070 and 2100 on fish eco‐physiology and behavior from 320 contrasts on 42 species, stemming from polar to tropical regions. Moreover, since organisms may experience a mosaic of carbonate chemistry in coastal environments (e.g., in estuaries, upwelling zones and intertidal habitats), which may have higher pCO2 values than open ocean waters, we assessed responses from additional 103 contrasts on 21 fish species using pCO2 levels well above IPCC projections. Under mid‐century and end‐of‐century CO2 emission scenarios, we found multiple CO2‐dose‐dependent effects on calcification, resting metabolic rate, yolk, and behavioral performances, along with increased predation risk and decreased foraging, particularly for larvae. Importantly, many of the traits considered will not confer fish tolerance to elevated CO2 and far‐reaching ecological consequences on fish population replenishment and community structure will likely occur. Extreme CO2 levels well above IPCC projections showed effects on fish mortality and calcification, while growth, metabolism, and yolk were unaffected. CO2 exposures in short‐term experiments increased fish mortality, which in turn decreased in longer‐term exposures. Whatever the elevated CO2 levels considered, some key biological processes (e.g., reproduction, development, habitat choice) were critically understudied. Fish are an important resource for livelihoods in coastal communities and a key component for stability of marine ecosystems. Given the multiple trait‐mediated effects evidenced here, we stress the need to fill the knowledge gap on important eco‐physiological processes and to expand the number and duration of ocean acidification studies to multi‐generational, multiple stressor (e.g., warming, hypoxia, fishing), and species interactions experiments to better elucidate complex ecosystem‐level changes and how these changes might alter provisioning of ecosystem services.

Continue reading ‘Living in a high CO2 world: a global meta‐analysis shows multiple trait‐mediated fish responses to ocean acidification’

Acidification in aquatic systems

Aquatic acidification is a proven phenomenon principally caused by human carbon dioxide emissions. Important changes in pH and on carbonate chemistry in conjunction with other anthropogenic impacts are seriously affecting aquatic communities. Nowadays, there is substantial evidence that acidification has an important impact on marine, coastal, and freshwater habitats. Calcifying organisms, juvenile stages, and coral reefs ecosystems are particularly vulnerable to this process. Species diversity and ecosystem resilience are expected to decrease in the near future. The amplitude of future acidification levels will depend on actual and future carbon dioxide emissions. Immediate actions are needed to limit the negative ecological and socioeconomic effects.

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Ocean acidification in the IPCC AR5 WG II

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