ATTACHED EPIFAUNA—SUBSTRATE RELATIONS

Examination of nine attached or sedentary epifaunal species in Buzzards Bay, Massachusetts, shows an anomalous distribution for Cliona celata. The other species are Microciona prolifera, Astrangia danae, Chaetopleura apiculata, Anadara transversa, Anomia simplex, Crepidula fornicata, C. plana, and C. convexa. With the exception of C. apiculata, all are suspension feeders. All forms except Crepidula are more abundant on bottoms with a low silt‐clay content and a mean grain diameter in the medium sand range. They are more plentiful in sediments coarser than those in which infaunal suspension feeders reach their maximum abundance. It is suggested that the stronger currents associated with coarser sediments provide an increased food supply that results in their more plentiful occurrence. All species, except the boring sulfur sponge C. celata, are found abundantly only on bottoms rich in dead shell material. The occurrence of C. celata is anomalous because, although it requires calcareous surfaces for initial fixation, the adult γ‐stage is more plentiful on bottoms poor in dead shells than elsewhere. It is suggested that C. celata reduces the abundance of dead shells through its boring activities, leading to a depletion of other species that require hard surfaces for fixation.