Influence of monsoon-driven hydrographic features on siphonophore assemblages in the Taiwan Strait, western North Pacific Ocean

Abstract

The spatial patterns of siphonophores were analysed in relation to local hydrographic features during two different monsoon seasons (the north-easterly monsoon in winter v. the south-westerly monsoon in summer) in the Taiwan Strait. Forty-eight species were identified, with five types of calycophoran siphonophores (Lensia subtiloides, Chelophyes appendiculata, Chelophyes contorta, Bassia bassensis, and Diphyes chamissonis) being most common in both seasons. Significantly higher abundances of four of the five common species were recorded in summer than in winter. Differences in the siphonophore species compositions were also observed between the northern and southern part of Taiwan Strait, with significantly higher diversity occurring in the southern waters. The distribution patterns of siphonophore assemblages were closely linked to the hydrographic features, influenced by the dynamic nature of the currents in the study area, with temperature, salinity and zooplankton biomass being the three most important factors.