Warming Seawater around Japan Causes Rapid Northward Expansion of Coral Distribution

Copyright National Institute for Environmental Studies

The National Institute for Environmental Studies (NIES) reported on January 21, 2011, that corals in temperate waters off Japan have expanded their habitat ranges northward in response to warming sea surface temperatures, and that the expansion rate is as fast as 14 kilometers per year. The report sets a global precedent for demonstrating on a national scale the northward expansion of coral distribution.

Japan is located at the northern edge of the geographic distribution of corals. Changes in coral distribution can therefore provide clues for evaluating the impact of global warming on coral species. Researchers at NIES analyzed over the past 80 years the coral habitats of nine coral species across 10 waters surrounding a region of Japan stretching from its southern end to its mid-east (from the Tokara islands in Kagoshima Prefecture to Tateyama in Chiba Prefecture). The results revealed that coral species are expanding in a northern direction. The average winter sea surface temperature in studied waters has risen by 1.1 to 1.6 degrees Celsius over the past 100 years.

Among nine species, no species has shifted its distribution rage to the south or reduced its coverage. Four species have actually expanded their distribution limits to the north. The expansion rate of these species varies from 2 to 14 kilometers per year. The highest rate was presented by a tropical species and is far greater than the expansion rate of any other studied life form, whether it be a northward shift or simple expansion of its habitat.

Coral reefs play an important role in photosynthetic primary production. They form diverse ecosystems that are home to a variety of marine life. The northward expansion of corals revealed by this study suggests the possibility that rapid changes are taking place in marine ecosystems as a result of warming sea surface temperatures, especially in temperate waters.

Japanese Coral Reefs Still at Risk: Increased Damage by Bleaching and Predatory Starfish (Related JFS article)
http://www.japanfs.org/en/pages/025749.html

Posted: 2011/04/27 06:00:15 AM