Planktonic copepod compositions and their relationships with water masses in the southern Taiwan Strait during the summer upwelling period

摘要

The species composition and distribution of planktonic copepods in relation to hydrographical characteristics in the southern Taiwan Strait were investigated during the summers of 1988, 1994, 2005 and 2006. Two station groups (I and II) and two copepod assemblages (nearshore and offshore) based on sea surface temperature, salinity, chlorophyll a and copepod abundance were revealed through cluster and detrended correspondence analysis. Station-group I was found in nearshore regions including the upwelling areas, and primarily consisted of coastaleritic species; while station-group II was found in offshore regions and primarily consisted of oceanic species. Indicator analysis identified the coastaleritic species Temora turbinata and Acrocalanus gibber are good indicators of the nearshore assemblage. The oceanic species Paraeuchaeta russelli and 6 additional species are indicators of the offshore assemblage. The results showed that Acartia pacifica is an indicator species of coastal waters with freshwater runoff, and Calanus sinicus is an indicator species of hypothermic upwelled waters in the southern Taiwan Strait during summer.