Factors affecting mortality of the scallop Chlamys asperrima (Lamarck) and its epizooic sponges in South Australian waters

This paper examines the effects of epizooic sponge cover, scallop size, and height of byssal attachment above sea-bed level on the survival of the scallop Chlamys asperrima (Lamarck) and its epizooic sponges. The presence of a sponge on a scallop increased survival in the field and in caging experiments. Mortality of small scallops was greater than that of larger ones, but small sponge-covered scallops suffered less predation than large bare ones. Attachment at the sea-bed level adversely affected both scallops and sponges. Scallops were more susceptible to starfish predation at sea-bed level, while sponges experienced more siltation and abrasion. Potential benefits of a mutualism are discussed.