Posts Tagged 'review'



Experimental assessments of marine species sensitivities to ocean acidification and co-stressors: how far have we come?

Experimental studies assessing the potential impacts of ocean acidification on marine organisms have rapidly expanded and produced a wealth of empirical data over the past decade. This perspective examines four key areas of transformative developments in experimental approaches: (1) methodological advances; (2) advances in elucidating physiological and molecular mechanisms behind observed CO2 effects; (3) recognition of short-term CO2 variability as a likely modifier of species sensitivities (Ocean Variability Hypothesis) and (4) consensus on the multistressor nature of marine climate change where effect interactions are still challenging to anticipate. No single experiment allows predicting the fate of future populations. But sustaining the accumulation of empirical evidence is critical for more robust estimates of species reaction norms and thus for enabling better modeling approaches. Moreover, advanced experimental approaches are needed to address knowledge gaps including changes in species interactions, intra-specific variability in sensitivity and its importance for the adaptation potential of marine organisms to a high CO2 world.

Continue reading ‘Experimental assessments of marine species sensitivities to ocean acidification and co-stressors: how far have we come?’

Predicting which species succeed in climate-forced polar seas

Understanding the mechanisms which determine the capacity of any species to adapt to changing environmental conditions is one of the foremost requirements in accurately predicting which populations, species and clades are likely to survive ongoing, rapid climate change. The polar oceans are amongst the most rapidly changing environments on Earth with reduced regional sea ice duration and extent, and their fauna’s expected sensitivity to warming and acidification. These changes potentially pose a significant threat to a number of polar fauna. There is, therefore, a critical need to assess the vulnerability of a wide range of species to determine the tipping points or weak links in marine assemblages. Knowledge of the effect of multiple stressors on polar marine fauna has advanced over the last 40 years, but there are still many data gaps. This study applies ecological risk assessment techniques to the increasing knowledge of polar species’ physiological capacities to identify their exposure to climate change and their vulnerability to this exposure. This relatively rapid, semi-quantitative assessment provides a layer of vulnerability on top of climate envelope models, until such times as more extensive physiological data sets can be produced. The risk assessment identified more species that are likely to benefit from the near-future predicted change (the winners), especially predators and deposit feeders. Fewer species were scored at risk (the losers), although animals that feed on krill scored consistently as under the highest risk.

Continue reading ‘Predicting which species succeed in climate-forced polar seas’

Antarctic marine biodiversity: adaptations, environments and responses to change

Animals living in the Southern Ocean have evolved in a singular environment. It shares many of its attributes with the high Arctic, namely low, stable temperatures, the pervading effect of ice in its many forms and extreme seasonality of light and phytobiont productivity. Antarctica is, however, the most isolated continent on Earth and is the only one that lacks a continental shelf connection with another continent. This isolation, along with the many millions of years that these conditions have existed, has produced a fauna that is both diverse, with around 17,000 marine invertebrate species living there, and has the highest proportions of endemic species of any continent. The reasons for this are discussed. The isolation, history and unusual environmental conditions have resulted in the fauna producing a range and scale of adaptations to low temperature and seasonality that are unique. The best known such adaptations include channichthyid icefish that lack haemoglobin and transport oxygen around their bodies only in solution, or the absence, in some species, of what was only 20 years ago termed the universal heat shock response. Other adaptations include large size in some groups, a tendency to produce larger eggs than species at lower latitudes and very long gametogenic cycles, with egg development (vitellogenesis) taking 18–24 months in some species. The rates at which some cellular and physiological processes are conducted appear adapted to, or at least partially compensated for, low temperature such as microtubule assembly in cells, whereas other processes such as locomotion and metabolic rate are not compensated, and whole-animal growth, embryonic development, and limb regeneration in echinoderms proceed at rates even slower than would be predicted by the normal rules governing the effect of temperature on biological processes. This review describes the current state of knowledge on the biodiversity of the Southern Ocean fauna and on the majority of known ecophysiological adaptations of coldblooded marine species to Antarctic conditions. It further evaluates the impacts these adaptations have on capacities to resist, or respond to change in the environment, where resistance to raised temperatures seems poor, whereas exposure to acidified conditions to end-century levels has comparatively little impact

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Coral reefs of the Red Sea — challenges and potential solutions

The Red Sea is a unique body of water, hosting some of the most productive and diverse coral reefs. Human populations along coasts of the Red Sea were initially sparse due to the hot and arid climate surrounding it, but this is changing with improved desalination techniques, accessible energy, and increased economic interest in coastal areas. In addition to increasing pressure on reefs from coastal development, global drivers, primarily ocean acidification and seawater warming, are threatening coral reefs of the region. While reefs in southern sections of the Red Sea live near or above their maximum temperature tolerance and have experienced bleaching events in the recent past, coral reefs in northern sections are considered a coral reef refugia from global warming and acidification, at least for the coming decades. Such differential sensitivities along the latitudinal gradient of the Red Sea require differential solutions and management. In an effort to identify the appropriate solutions to conserve and maintain resilience of these reefs along a latitudinal gradient, we used a SWOT analysis (strengths/weaknesses/opportunities/threats) to frame the present situation and to propose policy solutions as useful planning procedures. We highlight the need for immediate action to secure the northern sections of the Red Sea as a coral reef climate change refuge by management and removal of local stressors. There is a need to strengthen the scientific knowledge base for proper management and to encourage regional collaboration on environmental issues. Based on scientific data, solutions such as marine protected areas, fishing regulation, and reef restoration approaches were ranked for five distinct latitudinal sections in the Red Sea and levels of interventions are recommended.

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Ocean acidification in the Baltic Sea: involved processes, metrology of pH in brackish waters, and calcification under fluctuating conditions

The oceanic uptake of anthropogenic CO2 emissions counteracts global warming, but comes at the cost of Ocean Acidification, which is a threat to many marine organisms. In the Baltic Sea, the acidification process and its impact could so far not be quantified due to a lack of appropriate pH measurement techniques and the large pH variability. Looking back, in the first focus of this study acidification scenarios are derived from a detailed analysis of past alkalinity trends in the Baltic Sea water, which are put into context of the atmospheric CO2 forcing. In the second focus, the scientific basis for meaningful pH measurements in brackish waters is formed. Therefore, pH buffer solutions are characterized as primary standards and used to calibrate high-quality spectrophotometric pH measurements. In the last focus, pH fluctuations in benthic ecosystems are quantified. The importance of periods with high pH, during which organisms can maintain calcification rates even under acidified conditions, are highlighted.

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Phytoplankton responses to ocean climate change drivers: interaction of ocean warming, ocean acidification and UV exposure

Aquatic primary producers constitute only 1% of the global biomass, but their production equals that of all terrestrial ecosystems taken together (cf. Chapter 3, this volume). They take up a large fraction of anthropogenically emitted CO2, thereby mitigating climate change.

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The carbon dioxide vents of Ischia, Italy, a natural system to assess impacts of ocean acidification on marine ecosystems: an overview of research and comparisons with other vent systems

As the ocean continues to take up carbon dioxide (CO2), it is difficult to predict the future of marine ecosystems. Natural CO2 vent sites, mainly of volcanic origin, that provide a pH gradient are useful as a proxy to investigate ecological effects of ocean acidification.

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Ocean acidification in the IPCC AR5 WG II

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