Statistical analysis on ecological adaptation of pelagic Amphipoda in the East China Sea

This article studied the diversity of Amphipoda’s environmental adaptation using statistic methodology based on the seasonal investigation data obtained from the East China Sea waters(23°30-33°N,118°30-128°E) from 1997 to 2000.Fifty-four Amphipoda species were identified:among which eight species could stand a temperature difference over 10°C and eight species could tolerate the temperature gap ranged from 5 to 10°C;while only six species could stand the salinity fluctu-ation more than 5.Based on above facts as well as calculated optimal temperature and salinity we divided all Amphipoda species into four groups:(1) eurythermic and euryhalinous species including Lestrigonus schizogeneios,L.macrophthalmus,Tetrathyrus forcipatus,L.bengalensis and Hyperi-oides sibaginis;(2) temperate-warm species containing Hyperoche medusarum,Parathemisto gaudichaudi,Themisto japonica and Hyperia galba;(3) oceanic tropical species consisted of Oxycephalus clausi,Lycaea pulex,Eupronoe minuta,Simorhychotus antennarius,O.poreelus,Platyscelus ovoides and Rhabdosoma ahitei;(4) subtropical species involving one nearshore subtropical water species(Corophium uenoi) and 37 off shore subtropical ones.Compared with other zooplankton such as Euphausia and Chaetognatha,Amphipoda was characterized by low dominance but wide distribution in the East China Sea,and this could be ascribed to its high adaptation diversity.