Archive for September, 2009

Lautenberg teams with actress to protect oceans

Acidity in the world’s oceans will double by the end of the 21st Century if the world continues burning fossil fuels, Sen. Frank Lautenberg, R-N.J., and actress Sigourney Weaver said at a press conference in Washington Tuesday.

Lautenberg and Weaver, who is also an environmental activist, joined scientists with the Natural Resources Defense Council to urge Congress to protect oceans from carbonic acid that forms when carbon dioxide in the air mixes with water. The process threatens marine life, particularly shellfish and coral reefs.

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Imaging intracellular pH in a reef coral and symbiotic anemone

The challenges corals and symbiotic cnidarians face from global environmental change brings new urgency to understanding fundamental elements of their physiology. Intracellular pH (pHi) influences almost all aspects of cellular physiology but has never been described in anthozoans or symbiotic cnidarians, despite its pivotal role in carbon concentration for photosynthesis and calcification. Using confocal microscopy and the pH sensitive probe carboxy SNARF-1, we mapped pHi in short-term light and dark-incubated cells of the reef coral Stylophora pistillata and the symbiotic anemone Anemonia viridis. In all cells isolated from both species, pHi was markedly lower than the surrounding seawater pH of 8.1. In cells that contained symbiotic algae, mean values of pHi were significantly higher in light treated cells than dark treated cells (7.41 ± 0.22 versus 7.13 ± 0.24 for S. pistillata; and 7.29 ± 0.15 versus 7.01 ± 0.27 for A. viridis). In contrast, there was no significant difference in pHi in light and dark treated cells without algal symbionts. Close inspection of the interface between host cytoplasm and algal symbionts revealed a distinct area of lower pH adjacent to the symbionts in both light and dark treated cells, possibly associated with the symbiosome membrane complex. These findings are significant developments for the elucidation of models of inorganic carbon transport for photosynthesis and calcification and also provide a cell imaging procedure for future investigations into how pHi and other fundamental intracellular parameters in corals respond to changes in the external environment such as reductions in seawater pH.

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The coral reef crisis: The critical importance of <350 ppm CO2

Temperature-induced mass coral bleaching causing mortality on a wide geographic scale started when atmospheric CO2 levels exceeded not, vert, similar320 ppm. When CO2 levels reached not, vert, similar340 ppm, sporadic but highly destructive mass bleaching occurred in most reefs world-wide, often associated with El Niño events. Recovery was dependent on the vulnerability of individual reef areas and on the reef’s previous history and resilience. At today’s level of not, vert, similar387 ppm, allowing a lag-time of 10 years for sea temperatures to respond, most reefs world-wide are committed to an irreversible decline. Mass bleaching will in future become annual, departing from the 4 to 7 years return-time of El Niño events. Bleaching will be exacerbated by the effects of degraded water-quality and increased severe weather events. In addition, the progressive onset of ocean acidification will cause reduction of coral growth and retardation of the growth of high magnesium calcite-secreting coralline algae. If CO2 levels are allowed to reach 450 ppm (due to occur by 2030–2040 at the current rates), reefs will be in rapid and terminal decline world-wide from multiple synergies arising from mass bleaching, ocean acidification, and other environmental impacts. Damage to shallow reef communities will become extensive with consequent reduction of biodiversity followed by extinctions. Reefs will cease to be large-scale nursery grounds for fish and will cease to have most of their current value to humanity. There will be knock-on effects to ecosystems associated with reefs, and to other pelagic and benthic ecosystems. Should CO2 levels reach 600 ppm reefs will be eroding geological structures with populations of surviving biota restricted to refuges. Domino effects will follow, affecting many other marine ecosystems. This is likely to have been the path of great mass extinctions of the past, adding to the case that anthropogenic CO2 emissions could trigger the Earth’s sixth mass extinction.
Continue reading ‘The coral reef crisis: The critical importance of <350 ppm CO2’

Multi-decadal variations in calcareous holozooplankton in the California Current System: Thecosome pteropods, heteropods, and foraminifera

We examine long-term (1951–2008) variability of three major taxa of calcareous holozooplankton (aragonite-secreting thecosome pteropods and heteropods, and calcite-secreting large planktonic foraminifera) in light of recent interest in the impingement of waters undersaturated with respect to aragonite onto continental shelf depths in the California Current System. We assess interannual variability in springtime abundances of zooplankton sampled in the epipelagic layer, using CalCOFI (California Cooperative Oceanic Fisheries Investigations) zooplankton samples from two regions: Southern California (SC) and Central California (CC). Thecosome pteropods show no evidence of recent declines in abundance in SC or CC waters. In SC, sampling was sufficient to conclude that heteropods and large foraminifera also show no evidence of declines in abundance in recent years. These results do not preclude as-yet undetected changes in vertical distributions or shell morphology, and underscore the importance of sustained in situ measurement programs in order to detect and understand changes to pelagic ecosystems.
Continue reading ‘Multi-decadal variations in calcareous holozooplankton in the California Current System: Thecosome pteropods, heteropods, and foraminifera’

Planetary boundaries: Consider all consequences

Ocean acidification has impacts other than simple changes in pH, and these may need boundaries too.

In their definition of planetary boundaries that humans should not transgress for fear of “deleterious or even catastrophic consequences for large parts of the world’s inhabitants”, Rockström et al. (Nature 461, 472–475; 2009) consider ocean acidification as an essential part of the equation. This may be true whether we consider “inhabitants” to be all life or only humans, for the ocean and its resources are deeply embedded in human culture. But the authors’ suggested boundary, based on aragonite saturation — a measure of the extent to which seawater is saturated with the carbonate mineral — needs careful examination.
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Climate Change Science Compendium 2009

The Climate Change Science Compendium is a review of some 400 major scientific contributions to our understanding of Earth Systems and climate that have been released through peer-reviewed literature or from research institutions over the last three years, since the close of research for consideration by the IPCC Fourth Assessment Report.

The Compendium is not a consensus document or an update of any other process. Instead, it is a presentation of some exciting scientific findings, interpretations, ideas, and conclusions that have emerged among scientists.
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Acid Test: The Global challenge of ocean acidification (movie)

ACID TEST, a film produced by NRDC, was made to raise awareness about the largely unknown problem of ocean acidification, which poses a fundamental challenge to life in the seas and the health of the entire planet. Like global warming, ocean acidification stems from the increase of carbon dioxide in the earth’s atmosphere since the start of the Industrial Revolution.
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TEEB Climate Issues Update

In this report, they assessed the economic magnitude of the human welfare impacts of losing natural areas, especially forests. They described in economic terms the fundamental links between eliminating poverty and conserving biodiversity and ecosystems. They highlighted ethical issues underlying the choice of discount rates to evaluate the benefits of wild nature for human welfare. They also prepared the ground for phase 2 of teeb with some preliminary analysis of the policy implications of available economic evidence.
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Planktic foraminiferal shell thinning in the Arabian Sea due to anthropogenic ocean acidification? (update)

About one third of the anthropogenic carbon dioxide (CO2) released into the atmosphere in the past two centuries has been taken up by the ocean. As CO2 invades the surface ocean, carbonate ion concentrations and pH are lowered. Laboratory studies indicate that this reduces the calcification rates of marine calcifying organisms, including planktic foraminifera. Such a reduction in calcification resulting from anthropogenic CO2 emissions has not been observed, or quantified in the field yet. Here we present the findings of a study in the Western Arabian Sea that uses shells of the surface water dwelling planktic foraminifer Globigerinoides ruber in order to test the hypothesis that anthropogenically induced acidification has reduced shell calcification of this species. We found that light, thin-walled shells from the surface sediment are younger (based on 14C and δ13C measurements) than the heavier, thicker-walled shells. Shells in the upper, bioturbated, sediment layer were significantly lighter compared to shells found below this layer. These observations are consistent with a scenario where anthropogenically induced ocean acidification reduced the rate at which foraminifera calcify, resulting in lighter shells. On the other hand, we show that seasonal upwelling in the area also influences their calcification and the stable isotope (δ13C and δ18O) signatures recorded by the foraminifera shells. Plankton tow and sediment trap data show that lighter shells were produced during upwelling and heavier ones during non-upwelling periods. Seasonality alone, however, cannot explain the 14C results, or the increase in shell weight below the bioturbated sediment layer. We therefore must conclude that probably both the processes of acidification and seasonal upwelling are responsible for the presence of light shells in the top of the sediment and the age difference between thick and thin specimens.
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The last chapter of the “Guide to Best Practices in Ocean Acidification Research and Data Reporting” is available for open review

The Guide to Best Practices in Ocean Acidification Research and Data Reporting is intended as a reference to provide guidance for research in the rapidly growing field of ocean acidification. Its preparation was initiated by the European Project on Ocean Acidification (EPOCA) and the International Oceanographic Commission (IOC) and sponsored by EPOCA, IOC, the Scientific Council on Oceanic Research (SCOR), the U.S. Ocean Carbon and Biogeochemistry Project (OCB), and the Kiel Excellence Cluster “The Future Ocean”.
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