Seasonal and Spatial Variations in the Planktonic Copepod Community of Ilan Bay and Adjacent Kuroshio Waters off Northeastern Taiwan

copepod community of Ilan Bay and adjacent Kuroshio waters off northeastern Taiwan. Zoological Studies 48(2): 151-161. Knowledge of seasonal fluctuations in the planktonic copepods in waters off northeastern Taiwan is rather limited. To construct certain preliminary information, the investigation of marine copepods is necessary and important. Plankton samples for copepod studies were seasonally collected by a single vertical haul at each station with a ring trawl net of 335 μm mesh size at 5 fixed stations along a transect extending eastward from Ilan Bay to about 40 nautical miles (approx. 72 km) offshore in 2005. In total, 128 species of copepods belonging to 4 orders, 24 families, and 49 genera were identified. Twenty-three dominant species contributed to the main components of seasonal abundance of the copepod community. Four of these, i.e., Paracalanus aculeatus, Corycaeus (Agetus) typicus, Oncaea mediterranea, and O. venusta, were the most widely distributed species that occurred at all stations in each season. We found copepod abundances to be higher on the continental shelf waters and lower in Kuroshio waters, but the number of species was higher in Kuroshio waters than on the continental shelf. Obvious seasonal fluctuations in the composition of dominant species were observed based on replacement rates (25.0%-61.9%) at all stations. Geographical variations in distributional associations of the copepod community occurred over a seasonal scale, and the intermediate region was mainly influenced by the Kuroshio Current. Calanus sinicus might be considered an indicator