Jellyfish assemblages are related to interplay waters in the southern east China Sea

Abstract

Zooplankton communities are affected by spatial and temporal factors, as well as by general weather conditions, monsoons, and ocean currents. Present study examined the effects of typhoons, monsoons, and interplay waters on jellyfish assemblages in the complex hydrosystem in the coastal areas of the southern East China Sea. The species and composition of jellyfish and their seasonal succession in the coastal areas of northern Taiwan were investigated through 6 research cruises between October 2007 and January 2009. Among the samples obtained during these cruises, 23 jellyfish species from 2 classes, 7 orders, 13 families, and 19 genera were identified. The 3 most abundant jellyfish species were Nausithoe punctata (relative abundance, RA: 91.72%), Aglaura hemistoma (RA: 4.20%), and Diphyes chamissonis (RA: 1.13%). The species A. hemistoma exhibited the highest occurrence ratio (OR, 52.78%), and only this species was observed during all 6 research cruises. The abundance of Corymorpha bigelowi and Lensia multicristata correlated significantly and positively with seawater temperature, indicating that these species are brought to northeastern Taiwan by the warm Kuroshio Current. The formation of an N. punctata bloom yielded a density of 543.25 individuals/m−3 in October 2008, indicating that the jellyfish assemblage was influenced by a typhoon event and exhibited a clear pattern of seasonal succession. However, the interplay waters of the China Coastal Current and Kuroshio Current had a greater influence in shaping the jellyfish assemblage structure than did either typhoons or monsoons.