Study on the ecological characteristics of Chaetognatha in waters of southern Huanghai Sea and East China SeaⅠ. The characteristics of quantitative distribution

On the basis of investigation data of 12 cruises from December 1977 to November 1978 in waters of southern Huanghai Sea and East China Sea(28~34°N,120°30'~127°00'E).Dynamics of the temporal and spacious quantitative distribution of Chaetognatha and their relations to the environmental factors were analyzed.As results,higher density of Chaetognatha occurs from June to September and the highest in July,and it was low from January to April,especialy the lowest in April in this region,in which Sagitta enflata,S.crassa,S.nagae and S.bedoti were dominant species.The Chaetognatg a density in the northern Changjiang Riverestuary was higher than in the southern Chang jiang River estuary.High density occurred in all seasons except for summer in southern Huanghai Sea,when it generally occurred in mixing waters from various sources,especially in the front of Chang jiang River brackish water,coastal currents,high temperature and high salinity Kuroshio and Taiwan warm water currents and these species gave a certain indication of the wax and wan movement of different water systems in the study area.