Abstract
Spatial statistics was applied to the dataset collected in the Matsunase tidal flat in Mie Prefecture, Japan, in order to elucidate the effect of physico-biological factors that restrict spatial pattern of Manila clam, Ruditapes philippinarum, with spatial autocorrelation considered. Among 12 independent variables, the clam abundance was positively correlated with abundance of cyanobacterium (P < 0.05; partial Mantel test) and negatively correlated with ground elevation (P < 0.05), while diversity of macrofauna was marginally significant (P < 0.1). Faunal diversity was strongly correlated with ground elevation rather than the clam abundance. Manila clam was dominant in the study site and mainly lived in the offshore half of the intertidal zone. The upper margin of the clam habitat was close to the lower end of the swash bar. These results suggested that environmental factors relevant to ground elevation, i. e. extreme temperature and food insufficiency, could restrict vertical range of the clam habitat, inspiring what factor should be focused in future studies.
