Study on relationship between pelagic copepods and environmental factors at frequent HAB areasin the East China Sea in spring

An oceanographic comprehensive survey was carried out in the area of the East China Sea (122°00′-123°30′E、29°00′-32°00′N) during the period of April to May, 2002. The copepods samples were collected using zooplankton net of mesh size 0.505mm. Some community ecology of pelagic copepods including community abundance, characteristics, composition, dominant species and its correlation with environmental factors and red tide species were approached. The results show that there were 40 species of copepods in the investigated area of which Calanus sinicus, Euchaeta larvae and Euchaeta concinna were dominant species (dominance Y≥0.02). The average abundance of copepods was 154.97 ind·m-3 (5.00-649.85 ind·m-3) and the highest abundance was above 500 ind·m-3 occurring in east waters of estuary of the Changjiang River (east of 30°30′-31°15′N, 123°15′E). The diversity index in offshore area was higher than that in pelagic sea at the north of estuary of the Changjiang River, whereas the fact was on the contrary at the south of estuary of the River. The variation of copepods species was significantly and positively correlated with sea surface temperature (℃)(R=0.713,P0.01), and its abundance was correlated in nonlinearity with both diatom and Noctiluca scintillans abundance; the former can be described by fertility vs yield model and the latter expressed by effectively cumulated temperature model.