Copepod Assemblages and Diel Vertical Migration In the East China Sea, North of Taiwan

Abstract

The western North Pacific north of Taiwan is an area with high oc?anographie complexity, both biological and physicochemical. The northward flowing Kuroshio Current passes here and turns northeastward at the break of the East China Sea continental shelf, inducing an upwelling. We used a NorPac plankton net with opening-closing mechanism to take plankton samples at six depth levels (0, 50, 100, 150, 200, and 250 m) in four time series (00:00, 08:00, 15:00, and 21:00 local time) within 24 hours. Planktonic copepods were identified to species level when possible; depth and time of collecting, and abundance in individuals/nr were recorded. Different patterns of diel vertical migration (DVM) were established for the dominant species, such as normal DVM in Paracalanus aculeatus, Clausocalanus furcatus, Temora dlscaudata, and Canthocalanus pauper, reverse DVM in Olthona atl?ntica, no apparent DVM in Oncaea venusta and Subeucalanus mucronatus, and bimodal vertical distribution in Clausocalanus mastlgophorus and Cosmocalanus darwlnl. Four sampling groups and four copepod species assemblages were defined by using cluster analysis. Each of these sampling groups and species assemblages is characterized by a different DVM pattern.