Diet and stable isotope ratios of gut contents and gonad of the sea urchin Anthocidaris crassispina (A. Agassiz) in two different adjacent habitats, the Sargassum area and Corallina area

Abstract

Anthocidaris crassispina collected from the Sargassum area and neighboring Corallina area were examined for their diet, and the stable isotope ratios of gonad and gut contents. Sargassum spp. were primary constituents of gut contents in both habitats, the percentages of them in the Corallina area were less than those in the Sargassum area and the other constituents were almost all calcareous algae. In the stable isotope analyses, gut contents were significantly different, but gonads were not significantly different between two habitats. It is suggested that there were abundant food sources in the Sargassum area, in contrast to the Corallina area where drifting seaweeds compensate the shortage of food supply from this area.