Zoological Studies

Spatial Distribution of Copepods in Surface Waters of the Southeastern Taiwan Strait

Wen-Tseng Lo, Jiang-Shiou Hwang and Qing-Chao Chen (2004) Those were investigated during 16-19 June 1998. In all, 90 species of copepods were identified. The mean numerical abundance of copepods was 37.9 ± 12.7 individuals m^-3. Among these species, Acrocalanus gracilis, with an occurrence rate of 86%, was the most dominant taxon, contributing 37% to the numerical total of copepods. Other dominant copepods included Undinula vulgaris (11%), Oncaea venusta (7%), and Farranula gibbula (6%). The numerical abundance and species richness of copepods were higher in the waters south of the Penghu Islands. This area is affected by topographical upwelling due to the northwardflowing Kuroshio Current and South China Sea waters meeting the shallower shelf of the Taiwan Strait. Meanwhile, the lowest abundance and species richness of copepods were found at stations near the center of the Strait. Distribution patterns varied with different species, e.g., Acrocalanus gracilis, Undinula vulgaris, and Oncaea venusta had higher abundances in waters southwest of the Penghu Islands, while Farranula gibbula had higher abundance in coastal waters. Other dominant copepods exhibited higher abundances in coastal waters associated with either topographic or hydrographic conditions. Three station groups were defined using cluster analysis: southern stations off the Penghu Islands, stations near the center of the Taiwan Strait, and stations in the Penghu Channel. The last station group was particularly distinct from the others. Three copepod species groups were also distinguished and are herein discussed.