Abstract: Based on the two cruises investigation in Acipenser sinensis Natural Reserve and its adjacent waters (31°1958′N〖KG-*2〗-〖KG-*7〗31°38′N, 121°3208′N〖KG-*2〗-〖KG-*7〗122°11.65′E) in May and August 2004, the seasonal variations of species composition and quantitative distribution of fish eggs and larvae in the study area were studied, with the relevant environmental affecting factors analyzed. The results showed that in study area, the species composition and quantitative distribution of fish eggs and larvae varied remarkably in different seasons. The species composition varied greatly between May and August, and the species number was greater in May than in August. Coilia mystus was the dominant species, and its quantitative variation directly affected the variation of the total amount of fish eggs and larvae. The fish eggs and larvae had a smaller distribution range in August than in May, and mainly concentrated in the north branch waters and the southeast part of east tidal Chongming Island. Relatively small quantity of fish eggs and larvae was observed at the south coast of Chongming Island. Such a distribution feature of fish eggs and larvae basically reflected the differences in the seasonal variation of water movement, hydrological conditions, and wedging rate of seawater in the south and north branch waters in the study area.

Key words: Biosafety, Transgene escape, Ecological risk, Biodiversity