Ecology, distribution and demography of erect bryozoans in Mediterranean coralligenous reefs

Abstract

Coralligenous reefs are considered as one of the most important benthic ecosystems in the Mediterranean Sea in terms of biodiversity, ecosystem functioning, and aesthetic value. Bryozoans deserve special attention within the coralligenous framework fauna: they are among the most common animals, showing high diversity values and playing different functional roles. Distribution, spatial variability, and demographic features of five erect bryozoan taxa Adeonella sp., Myriapora truncata, Pentapora fascialis, Reteporella sp., and Smittina cervicornis were studied in the central Tyrrhenian Sea. Abundance, size, and relationship with other taxa/morphological groups of benthic organisms were studied in coralligenous reefs between 35 and 40 m depth. High density of colonies was reported especially in association to gorgonians and algae dominated assemblages. Size distributions of the five bryozoans were characterized by small colonies; only two species (P. fascialis and S. cervicornis) showed colonies larger than 50 cm2. Structure of coralligenous assemblages and disturbances outlined different ecological requirements of the five studied taxa. Results provide baseline information for monitoring trajectories of change of these organisms in the coralligenous ecosystem. To date, this work represents the first study exploring ecology and distribution patterns of common erect bryozoans in the Mediterranean Sea.