Winter distribution and composition of ichthyoplankton associated with thermal front on the continental shelf of the southern East China Sea.

Abstract

Our study of ichthyoplankton with oceanic observation on the continental shelf of the southern East China Sea was conducted on March 7 to 8, 2005. The maximum temperature and salinity gradients, about 0.15 oC/km and 0.099 psu/km respectively, were found between stations 2 and 3. A total of 1,388 fish larvae representing 49 families and 57 taxa were collected. Scomber australasicus, Trachurus japonicus, Engraulis japonicus, Amblychaeturichthys spp., and Myctophum asperum were the five most abundant taxa and accounted for 46.1, 12.6, 7.2, 6.3, and 4.9% of the total samples in numbers, respectively. Amblychaeturichthys spp. were most abundant in the coastal waters, while S. australasicus, T. japonicus, and M. asperum in the mixing waters of the shelf. E. japonicus dominated in the transition zone between these two waters. S. australasicus was dominant in yolk stage and E. japonicus and T. japonicus in pre-flexion stage. The dominant stages for Amblychaeturichthys spp. and M. asperum were pre-flexion and flexion. Using the Bray-Curtis dissimilarity, the eight most abundant identified taxa from 8 stations were classified into three species and three station groups respectively. Interpretations of ichthyoplankton diversity and distribution in relation to the thermal front were given.