Summer Distribution and Diversity of Copepods in Upwelling Waters of the Southeastern East China Sea

Abstract

We investigated the species composition and distribution of copepods in the East China Sea northeast of Taiwan during the summer of 1998. In total, 95 species of copepods belonging to 43 genera and 21 families were identified. Cluster analysis divided the sampling stations into 3 groups: A, B (comprised of subgroups B1 and B2), and C. Group A had the highest mean abundance but the lowest Shannon-Weaver species diversity and evenness index. Subgroups B1 and B2 had the lowest mean abundances but the highest values of species diversity and evenness index. Group C showed intermediate values for these factors. Satellite images of sea surface temperatures and in situ conductivity, temperature, and depth (CTD) data showed that group A stations were located in waters influenced by the Taiwan Strait Warm Current; those of subgroups B1 and B2 were distributed in waters near the continental slope in a cold-core eddy/upwelling area affected by the Kuroshio Current; and group C stations were in the northern part of the study area and were linked to continental mixed waters. Typical tropical copepod species, such as Canthocalanus pauper, Undinula vulgaris, Acrocalanus gibber, Paracalanus aculeatus, and Temora turbinata were highly abundant in waters linked to both the Kuroshio and Taiwan Strait Warm Currents. Copepods with low abundance, such as Clausocalanus minor and Oithona plumifera were consistently found in the cold-core eddy/upwelling area. These results suggest that the distribution, abundance, and species composition of copepods are associated with different water masses in the upwelling waters off northeastern Taiwan.