Sea Technology

SEP 2012

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Regional Extinction Risk on the Rise for Parrotfish, Surgeonfish A study conducted for the International Union for Con- servation of Nature (IUCN) Red List of Threatened Species found that 86 percent of the populations of parrotfish and surgeonfish face a low risk of extinction globally but face a heightened risk regionally, especially in areas like the Coral Triangle. The results were published in July in PLoS ONE. Parrotfish and surgeonfish are important to fisheries and tourism, and are vital to the health of coral reefs, as they feed on and limit the growth of algae on coral. The Greenback Parrotfish, listed as endangered, and the Bumphead Parrotfish, listed as vulnerable, are large-bodied, long-lived species experiencing significant population de- clines from fishing pressure. The Kapingamarangi Surgeon- fish, provisionally listed as vulnerable, is only found in the Kapingamarangi Atoll, Caroline Islands. The Rainbow Parrotfish is presently listed as data defi- cient but has been proposed for listing as near threatened. It was previously listed as threatened because it had his- torically been fished to low numbers. Although the Rainbow Parrotfish has been found to have stabilized in small num- bers, it continues to suffer from decline due to destruction and loss of its mangrove habitats and overfishing. Researchers also conducted a survey of parrotfish and surgeonfish in the Coral Triangle region, which encompass- es much of Indonesia, Malaysia, the Philippines, Brunei, Timor L'Este, Papua New Guinea and the Solomon Islands. Of the 105 species of parrotfish and surgeonfish in the Coral Triangle, 18 are targeted by fisheries and 13 are at higher risk of extinction regionally versus globally. Conservation International said 120 million people in the Coral Triangle rely on fish as a primary protein source, and 95 percent of Southeast Asian coral reefs are threatened, par- ticularly by fishing. Marine Organisms Lighten Shells And Skeletons as Ocean Acidifies A study published in Global Change Biology in August suggested that increased ocean acidity is affecting the size and weight of shells and skeletons of marine organisms. These animals are an important food source for marine predators, as well as a valuable ingredient in human food production. Scientists from the British Antarctic Survey, the U.K.'s National Oceanography Centre, Australia's James Cook and Melbourne universities, and the National University of Sin- gapore investigated the natural variation in shell thickness and skeletal size of clams, sea snails, lampshells and sea urchins living in 12 different environments, ranging from the tropics to the polar regions. The researchers found that as the availability of calcium carbonate decreased, skeletons got lighter and accounted for a smaller part of the animal's weight. The same effect occurred consistently in all four marine-life types studied, which suggests the effect is widespread across marine spe- cies and that increasing ocean acidification will progres- sively reduce the availability of calcium carbonate. The ef- fect is strongest at low temperatures. The study suggests that given enough time and a suffi- ciently slow rate of change, marine life could evolve to sur- vive the acidifying oceans. n www.sea-technology.com SEPTEMBER 2012 / st 75

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