长江口及其邻近水域底栖动物生态特点

本文根据1982—1983年四个航次调查的定量资料,对长江口及其邻近水域的底栖动物的种类组成和生物量及栖息密度的分布进行叙述和讨论。调查结果:棘皮动物的生物量居首位,多毛类在调查区广为分布的类群,并占有较大的数量。生物量和栖息密度的分布极不均匀,高生物量和高栖息密度的分布趋势基本相似,两者都在调查区的北部。8月生物量最高,平均为23.27g/m^2;2月最低,平均为10.09g/m^2。8月栖息密度最高,平均为84.8个/m^2;2月最低,平均为20.1个/m^2。同时,还叙述甲壳类的豆形短眼蟹生物量和栖息密度的季节变化。

1998’s floods in the Changjiang River and the land use/land cover change in the upper and middle-lower reaches in the past 50 years

Flood of Changjiang River (the Yangtze) in 1998 is so serious that it arouses our keen concern about its causes. In this paper, the authors bring out a brief history of the flood disaster happened to the Changjiang River Valley in the last six centuries and analyze the causes for the frequent flood disaters based on the land use and land cover change in the upper and middle-lower reaches of the Changjiang River.