Mathematical analysis on adaptation of Heteropoda to different temperature and salinity in the East China Sea

Based on the data of four seasonal oceanographic censuses in the East China Sea(23°30′-33°N、118°30′-128°E) in 1997-2000,the paper identified ecotype of Heteropoda species,through fitting curve,forming mathematical model and calculating optimal temperature and salinity.The historical results from the study of geographic distribution were consulted as evidence.The results showed that Atlanta turriculata and Firoloida desmarest were qualified as oceanic tropical water species because over 25 ℃ their optimal temperature was over 25 ℃ and their optimal salinity was over or near 34,as well as their offshore distribution;The rest species are all offshore subtropical water species,among which Atlanta rosea showed its eurythermic feature;Atlanta peroni possessed relative low optimal temperature near 23 ℃ as well its euryhalinous characters;Atlanta lesueuri distributed in waters with average salinity over 34;Atlanta depressa distributed in offshore waters.Except for above mentioned species,the others are typical offshore subtropical water species.In general,Heteropoda,a zooplankton group,showed its ecotype as warm water character.The zooplanktons usually distributed in limited ranges of temperature and salinity.They are sensitive to change of temperature.All of these characters make them as good indicator species of water masses.Most Heteropoda species distributed in middle waters of the East China Sea(28°00′-30°00′N,124°E-126°E).They hardly traverse through the obstruction of cold water masses in the Yellow Sea.That is why they rarely occurred in the Yellow Sea and the Bohai Sea.The present results on the identification of ecotype of Heteropoda species will be beneficial to the study of meteorological oceanography,geological oceanography,physical oceanography and biological oceanography in the future.