Summer Assemblages and Biodiversity of Larval Fish Associated with Hydrography in the Northern South China Sea

Abstract

The objective of this study was to investigate the association between larval fish assemblages and the environmental factors in the northern South China Sea based on data collected during summertime. Shipboard measurements (Ocean Researcher 1 [cruise CR866], Fishery Researcher 1 [cruise FR1-2008-07-03]) of temperature and salinity profiles were obtained with a conductivity–temperature–depth profiler, and ichthyoplankton was collected with an Ocean Research Institute net. In total, 3,476 larval fishes and 188 taxa representing 80 families were identified. Myctophidae was the most common and abundant taxon in this area. The CPUE (individuals/1,000 m3) of fish larvae differed among sampling stations, with greater abundances at the shallower stations than at the deeper stations, and the species biodiversity at each station also varied. The results of grouping revealed that the spatial distribution of larval fish was divided into a shelf-based group and a pelagic-based group; these two groups were bounded by the 200-m isobath. Abundance of some larval fish was related to environmental factors, such as temperature, salinity, chlorophyll-a concentration, and mixing layer depth. These results indicated that the larvae of some species were more affected by natural environmental characteristics than by internal biological properties.