The Recent Terebratulina Community in the rocky subtidal zone of the Bay of Fundy, Canada

Abstract

A distinctive rocky subtidal benthic community (the Terebratulina community) is described from the Bay of Fundy, Canada. It consists of 3 closely interspersed subcommunities: a cavity sub-community characterized by chitons, coelenterates, brachiopods, bryozoans, chordates and annelids; a rock-face sub-community, similar in composition but enriched in brachiopods and sponges; and an upper-surface sub-community, dominated by algae, chitons, bivalves and echinoids. Comparison with recently described Jurassic, Cretaceous and Recent (Mediterranean) hard-ground communities suggests a relative constancy in composition, in terms of higher taxa, since the Mesozoic. Development of these (sub-)communities occurs wherever crevice or cavity systems on hard substrates lead to microenvironments differentiated mainly on the basis of water energy and light. The composition and trophic structure of the community and the life habits of Terebratulina septentrionalis (Couthouy) are related to aspects of the environment. Marked differences in composition between the living cavity sub-community and the death assemblage in the sediments are shown to be due to differential preservation, fragmentation, population dynamics and limited local transportation.