Effects of changes in seagrass shoot density and leaf height on the abundance of juveniles of Acentrogobius pflaumii in a Zostera marina bed

The effects of changes in the structural complexity of a seagrass (Zostera marina) habitat on the density of juveniles of the streaked goby, Acentrogo bius pflaumii, were investigated by field experimentation at Moroiso Bay, M iura Peninsula, Japan. The experimental design, which included seven treatm ents plus a control, included reduction of seagrass shoot densities and lea f heights as well as complete removal of seagrass. Throughout the study per iod,juvenile densities remained similar among the experimental quadrats, in cluding the completely cleared quadrat. On the other hand, juveniles did no t appear over the bare sandy substratum surrounding the experimental seagra ss bed. Within the bed, prey densities were high, being similar among the e xperimental quadrats, whereas prey were relatively scarce over the surround ing bare substratum. This result suggested that streaked goby juveniles wer e not attracted to the structure of the Zostera bed per se and that their d istribution patterns may be determined by other factors, such as prey avail ability.