Archive for March, 2008

Increased CO2 level threatens coral reefs

A coral reef is made up of thin layers of calcium carbonate (limestone) secreted over thousands of years by billions of tiny soft bodied animals called coral polyps. Coral reefs are the world’s most miscellaneous marine ecosystems and are home to twenty-five percent of identified marine species, including 4,000 species of fish, 700 species of coral and thousands of other plants and animals. Coral reefs occupy less than one quarter of one percent of the Earth’s marine environment, yet they are home to more than a quarter of all known fish species.

And these largest living structures on Earth and the millions of livelihoods which depend upon them are at risk, the most definitive review yet of the impact of rising carbon emissions on coral reefs has concluded. If world leaders do not immediately engage in a race against time to save the Earth’s coral reefs, these vital ecosystems will not survive the global warming and acidification projected for later this century.

It is very important that the public realises that the lack of sustainability in the world’s carbon emissions is causing the quick loss of coral reefs, the world’s most biodiverse marine ecosystem. The rise of carbon dioxide emissions and the resultant climate warming from the burning of fossil fuels are making oceans warmer and more acidic, which is triggering extensive coral disease and choking coral growth toward “a tipping point for functional collapse.”

The coral scientists point out that rising global CO2 emissions embody an ‘irreducible risk’ that will quickly outdo the capacity of local coastal managers and policy-makers to sustain the health of these critical ecosystems, if CO2 emissions are allowed to prolong unrestrained.

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ESF LESC/EuroCLIMATE Strategic Workshop on the “Impacts of Ocean Acidification”

Strategic Workshop on the “Impacts of Ocean Acidification”

Meloneras, Gran Canaria (ES), 28-30 Jan. 2008

Global change is evidenced mainly through the temperature increase observed since the pre-industrial period. It also encompasses other changes, such as perturbations in the biogeochemical cycles of the major (C, O, N, P) and minor (micro-nutrients) elements, in the ecosystem structure and dynamics (e.g., biodiversity loss), or in the related marine resources and services upon which human societies largely depend (e.g., energy, water, land use, fisheries).

However, one component rather neglected until recently is the Ocean Acidification, which relates to the anthropogenic increase in atmospheric CO2 content. It is now under intense scrutiny as it has recently reached some critical thresholds while its impacts on biological, biogeochemical, ecological, economic, social and climatic processes are often not well known or completely unknown, but are expected to be fast emerging and drastic.

Following the approval by the LESC Standing Committee to support a proposal submitted in early fall 2007 by Prof. Jelle Bijma, a strategic workshop has been recently organised, with co-sponsorship by the EUROCORES Programme EuroCLIMATE, to address the issue of the Impacts of Ocean Acidification. The main objectives of this strategic workshop were set as follows:

– Drafting a science policy briefing;

– Drafting a proposal for a new science programme (EUROCORES Theme proposal for 2008).

Continue reading ‘ESF LESC/EuroCLIMATE Strategic Workshop on the “Impacts of Ocean Acidification”’

Has the Great Barrier Reef got a future?

Once I would have thought that a ridiculous question. Yet today, if we assemble all the best science we have, the answer can at best be “maybe”.

It may seem preposterous that the greatest coral reef in the world – the biggest structure made by life on Earth – could be seriously (I mean genuinely seriously) threatened by climate change. The question itself is probably already relegated in your mind to a ‘here-we-go-again’ catch-bag of greenie diatribe about the state of our planet. This view is understandable given that even a decade ago, there were many scientists who had not yet come to grips with the full implications of climate change.

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Associate Scientist position, ocean acidification

The Cooperative Institute for Marine and Atmospheric Studies (CIMAS) of the University of Miami (UM) invites applications for a full-time position as an Associate Scientist. The successful applicant will initiate an interdisciplinary research program to examine the effect of anthropogenic climate perturbations on the health of oceanic ecosystems, with a focus on the impact of ocean acidification (OA). The incumbent’s research should take advantage of the ongoing related work at the Rosenstiel School of Marine and Atmospheric Sciences (RSMAS) of UM, the Atlantic Oceanographic and Meteorological Laboratory (AOML) of NOAA, and the Southeast Fisheries Science Center (SEFSC) of NOAA. Position #036590. A doctorate degree with a minimum of five years of relevant post-doctoral research experience is required. Include the names and e-mail addresses of three people who can provide letters of recommendation along with the CV.

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Postdoctoral Investigator – Geobiology Description

A postdoctoral position is available in the laboratories of Joan Bernhard and Dan McCorkle – Geology and Geophysics Department at the Woods Hole Oceanographic Institution starting in spring/summer 2008. The position is part of an NSF-funded project to determine the impact of rising seawater pCO2, as a result of increasing atmospheric carbon dioxide, on the health and survival of benthic foraminifera. The successful candidate will work with the PIs to refine the design of a series of time-course CO2 enrichment laboratory culture experiments, and will have principal responsibility for conducting those experiments (including determination of cell survival and of shell structure), and for subsequent data analysis and manuscript preparation. He or she also will participate in sample collection at sites in Scandinavia, New England, and Florida.

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The Next Ocean

Humanity’s extra CO2 could brew a new kind of sea

Terrie Klinger is starting to wonder about the future of kelp sex. It’s a delicate business in the best of times, and the 21st century is putting marine life to the acid test.

Klinger, of the University of Washington in Seattle, studies the winged and bull kelps that stretch rubbery garlands up from the seafloor off the nearby Pacific coast. These kelp fronds do no luring, touching, fusing of cells or other sexy stuff. Fronds just break out in chocolate-colored patches.

The patches release spores that swim off to settle on a surface and start the next generation. The new little kelps don’t look as if they belong to the same species, or even the same family, as their parents. The little ones just grow into strings of cells, but these are about sex.

“Those of us who have spent far too long looking at this can tell the males from the females,” says Klinger. The subtly female-shaped filaments form eggs and release kelp pheromones to call in the male filaments’ sperm.

Sex filaments have kept kelp species going for millennia, but Klinger says she wants to know what’s happening now that carbon emissions are changing seawater chemistry. The intricate reproductive cycle of kelp is an example of a delicate system that can experience big effects from seemingly small changes in ocean chemistry.

This chemistry is already shifting, powered by the increased concentration of carbon dioxide in the atmosphere from human activity. Not all the carbon dioxide from burning fossil fuels stays in the air. The oceans have absorbed about half of the CO2 released from burning fossil fuels since the beginning of the industrial age, says Richard Feely of the National Oceanic and Atmospheric Administration in Seattle. The ocean takes in about 22 million tons of CO2 a day, he says.

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Competition for inorganic and organic forms of nitrogen and phosphorous between phytoplankton and bacteria during an Emiliania huxleyi spring bloom

Using 15N and 33P, we measured the turnover of organic and inorganic nitrogen (N) and phosphorus (P) substrates, and the partitioning of N and P from these sources into two size fractions of marine osmotrophs during the course of a phytoplankton bloom in a nutrient manipulated mesocosm. The larger size fraction (>0.8 μm), mainly consisting of the coccolithophorid Emiliania huxleyi, but also including an increasing amount of large particle-associated bacteria as the bloom proceeded, dominated uptake of the inorganic forms NH4+, NO3, and PO43. The uptake of N from leucine, and P from ATP and dissolved DNA, was initially dominated by the 0.8–0.2 μm size fraction, but shifted towards dominance by the >0.8 μm size fraction as the system turned to an increasing degree of N-deficiency. Normalizing uptake to biomass of phytoplankton and heterotrophic bacteria revealed that organisms in the 0.8–0.2 μm size fraction had higher specific affinity for leucine-N than those in the >0.8 μm size fraction when N was deficient, whereas the opposite was the case for NH4+. There was no such difference regarding the specific affinity for P substrates. Since heterotrophic bacteria seem to acquire N from organic compounds like leucine more efficiently than phytoplankton, our results suggest different structuring of the microbial food chain in N-limited relative to P-limited environments.

Continue reading ‘Competition for inorganic and organic forms of nitrogen and phosphorous between phytoplankton and bacteria during an Emiliania huxleyi spring bloom’

Global warming poses deaf threat to tropical fish

Going deaf is not a problem that most of us would automatically associate with global warming. For coral reef fish, however, hotter seas could pose a real threat.

Young coral reef fish with misshapen ear bones are more likely to get lost and die, and exposure to warmer waters makes the problem worse, according to a study of fish living around Lizard Island on the Great Barrier Reef, Australia.

After hatching, most reef fish spend a few weeks out in the open ocean before returning to the reef to settle down. And it seems that sound is a key factor in guiding them to the right habitat.

The young fish have to home in on the high-frequency noises made by invertebrates like shrimp and sea urchins, and avoid the low-frequency noises made by crashing waves and adult fish.

Monica Gagliano at the Australian Institute of Marine Science in Townsville, Queensland, and colleagues found that at hatching, just over half of Ambon damselfish had asymmetrical otoliths, or ear bones.

Continue reading ‘Global warming poses deaf threat to tropical fish’

Dispersal without errors: symmetrical ears tune into the right frequency for survival.

Vertebrate animals localize sounds by comparing differences in the acoustic signal between the two ears and, accordingly, ear structures such as the otoliths of fishes are expected to develop symmetrically. Sound recently emerged as a leading candidate cue for reef fish larvae navigating from open waters back to the reef. Clearly, the integrity of the auditory organ has a direct bearing on what and how fish larvae hear. Yet, the link between otolith symmetry and effective navigation has never been investigated in fishes. We tested whether otolith asymmetry influenced the ability of returning larvae to detect and successfully recruit to favourable reef habitats. Our results suggest that larvae with asymmetrical otoliths not only encountered greater difficulties in detecting suitable settlement habitats, but may also suffer significantly higher rates of mortality. Further, we found that otolith asymmetries arising early in the embryonic stage were not corrected by any compensational growth mechanism during the larval stage. Because these errors persist and phenotypic selection penalizes asymmetrical individuals, asymmetry is likely to play an important role in shaping wild fish populations.

Continue reading ‘Dispersal without errors: symmetrical ears tune into the right frequency for survival.’

Reef fish lose their way as environment turns hostile

Environmental stresses, including warmer and more acidic seawater, may be affecting the development of the ear bones in young reef fish, causing the fish to get lost at sea during a crucial stage of their development.

Research by fish ecologists Dr Monica Gagliano (AIMS and James Cook University) and Dr Martial Depczynski (AIMS, Perth), with Dr Stephen Simpson from the University of Edinburgh and James Moore from JCU in Townsville, has found that fish with asymmetrical ear bones struggle to return to the reef.

The implications could be profound for the survival of reef ecosystems, which depend upon a rich biodiversity for effective function and health.

Continue reading ‘Reef fish lose their way as environment turns hostile’

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Ocean acidification in the IPCC AR5 WG II

OUP book