Habitat use and diet of larvae and juveniles of the goby Tridentiger brevispinis in the profundal and littoral zones in Lake Kitaura, Ibaraki Prefecture, Japan

摘要

The goby Tridentiger brevispinis is a common benthic fish in the lakes and swamps of temperate Japan and is commercially important for local fisheries. The distribution, migration and food habits of larvae and juveniles of the species in Lake Kitaura, Ibaraki Prefecture, central Japan were investigated in the profundal (6-7 m depth) and littoral (0.5-1 m depth) zones, from April 2010 to March 2012. Within a few days of hatching, preflexion larvae were dispersed throughout the surface and middle layers in the profundal zone, pelagic juveniles thereafter aggregating in the bottom layer. Newly-settled and benthic juveniles subsequently migrated from the profundal to the littoral zone. The major food components of juveniles changed from planktonic (cladocerans and cyclopoid copepods) to benthic items (gammaridean amphipods, chironomid larvae and filamentous algae) with the inshore migration. Analyses of the relationships between benthic juvenile density and a variety of environmental variables in the littoral zone, using generalized linear models, indicated that the depth of undercut bank at the reed belt edge and the mud content of sediment were the most significant determinants of juvenile densities. This suggested that reed belts in the littoral zone are an important nursery habitat for benthic juveniles of the goby.