Bryozoan communities and thanatocoenoses from submarine caves in the Plemmirio Marine Protected Area (SE Sicily)

Living and dead bryozoan communities from three caves in the "Plemmirio Marine Protected Area" (SE Sicily, Italy) were studied. Species richness from each cave and from the area as a whole (72 species) are comparable to those observed in other regions and caves within the Mediterranean. Communities consist largely of cave dwellers, sciaphilic and cryptic species, often related to coralligenous habitats, but include also some generalist species components. Bryozoans from hard surfaces (vaults, walls and floor) and bottom sediments were studied separately taking into account both living specimens and thanatocoenoses. According to previous data, communities of hard surfaces exhibit a trend of decreasing species richness towards the inner area and a clear patchiness, unlike those in sediments whose distribution appears strongly related to local sediment texture. Dead colonies and fragments from both hard surfaces and bottom sediments contribute valuable information concerning the pool of species potentially inhabiting caves. The usefulness and limits of different sampling methods for the study of cave bryozoans are discussed.