Temporal variability of density and diverse shell occupancy of Diogenes pugilator on a sandy bottom of the Levantine Sea and their biometrical relationships

摘要

Populations of Diogenes pugilator on the sand bottom of the Eastern Mediterranean showed annual density peaks in winter and summer. In a two-year period, monthly biomass and abundance did not vary statistically. Biomass and abundance ranged from up to 3000 g ha(-1) and 20000 ind ha(-1) to almost absence of specimens in autumn. Densities were negatively correlated with silt content of the sediment, but not with physical parameters of water or other sedimentary characters. Most individuals occupied shells of three nassarid gastropod species (Nassarius gibbosulus, N. circumcinctus and N. mutabilis) but shells from 27 species were found to be utilized. Diversity of the shells was variable throughout the year. Total length of the hermit crab accounted for 73% of the total variance in the discrimination of shell partition. Total lengths spanned to be shorter for the crabs occupying Phorcus nuaabilis and Muricopsis cristata than those inside the shells of Astraea sp. The shells of some species (Nassarius cuvierii, Ocinebrina aciculata, Strombus persicus and Nassarius wolffi) hosted light-weighed crabs with low statistical variation on the second component of the discriminant distance.