Title Effects of recent ecological events on the distribution and growth of macroalgae in marine waters around Taiwan
Authers Jui-Sheng Chang, and Chien-Chang Tseng
Citation Bull. Fish. Res. Agen. No.32, 11-17, 2010
Abstract
Macroalgal resources are particularly abundant in the northeast coast and Hengchung Peninsula in the southern part of Taiwan as well as in several smaller islands around Taiwan. Classified as being in the tropical and subtropical areas, the diversity of macroalgal species and seasonal growth types are based on their geographical distributions in different coasts of Taiwan. During the past years, there were more than 600 species of macroalgae identified with certainty. Basically, tropical macroalgae are found in the eastern and southern parts of Taiwan, Shiao-Liou-Chou Island, Green Island, and Orchid Island. The subtropical macroalgae mainly occurred in the northeast coast of Taiwan. Mixed tropical and subtropical macroalgae can be found in the Pescadores, the three Northern Islands, and Kueishan Island. Besides geographical distribution, the Kuroshio and its branch currents also can affect the distribution of tropical macroalgal species. Some subtropical macroalgae, such as Porphyra, Bangia, and Petalonia, can only grow in cool areas washed by the cold current coming from the coast of Mainland China. Giant kelps, such as Laminaria and Undaria, cannot be found in Taiwan and offshore tropical islands, but some of them are cultured in Kinmen Islands and Matsu Islands off the coast of nearby Fujian province.
 Recently, the macroalgal resources in Taiwan area have affected by global climate changes, coastal development, tourism, and environmental pollution. The species composition and cover of macroalgae in different coastal environments have changed as a result. For example, the mass proliferation of Codium species overgrows the hard corals in Nanwan Bay of Hengchung Peninsula. The diversity of corals decreased and the dominant benthos has phase-shifted from corals to macroalgae. In order to alleviate the situation, conservation organizations decided to increase the feeding pressure on the overgrowing macroalgae by prohibiting the harvest of herbivorous sea urchins from coral reefs. On the other hand, the coastal geomorphology of northeastern Taiwan was changed by several strong typhoons that struck during the past ten years. As a result, the harvest of some economic seaweeds such as Porphyra, Gelidium, Eucheuma, Grateloupia and so on declined dramatically. Gelidium harvest was also affected seriously by the release of herbivorous fish by some fishery groups. In February of 2008, a deep cold current was recorded in the Pescadores. The cold seawater caused more than ten thousand tons of fish to die. After this catastrophic event, studies have shown that macroalgae there grew more abundantly than ever before. It is obvious that recent ecological events have affected the normal distribution and growth of macroalgae around Taiwan and these phenomena should be further investigated.
URI http://www.fra.affrc.go.jp/bulletin/bull/bull32/11-17.pdf