九龙江口低盐区桡足类种类多样性最小现象的初步研究

Preliminary Study on the Species Minimum of Copepods in the Low Salinity Zone of Jiulongjiang Estuary

通过2003年5月至2004年2月间的4个调查航次,对沿九龙江口分布的桡足类种类数与盐度及盐度变化幅度的关系进行了初步研究.结果显示,该河口低盐区存在桡足类种类多样性最小现象,沿河口分布的桡足类种类数与所在水域的盐度变化幅度呈线性负相关,反映了剧烈的盐度变化对桡足类种类多样性的限制作用.桡足类有限的适盐能力和伴随潮汐垂直移动以借助水流迁移的行为则可能是形成在低盐区种类多样性最小现象的内因.

The relationship between species number of copepods and salinity or salinity range was investigated in 4 voyages from May 2003 to February 2004. The results revealed that there were species minimum of copepods in the low salinity zone （LSZ） between salinity of 5 to 10 of Jiulongjiang estuary and significant negative linear relationship between salinity range and species number of copepods along the estuary. While more species of copepods were found in the head and mouth of the estuary with lesser salinity range, fewer species of copepods were found in LSZ with strong salinity turbulence;these results indicated that salinity variation controlled the diversity of copepods along the estuary. The finite salinity tolerance and tidally-oriented vertical migration of copepods might be the intrinsic reasons for the phenomenon of species minimum in LSZ.