Aliens associating with Caspian Sea endemic bivalves

Endemic species of the Caspian Sea fauna and flora are potentially and actually threatened by invasive species, particularly since the opening of the Volga-Don Shipping Canal in 1952. While the invaders are more or less known, their impact on the Caspian ecosystem is poorly understood, maybe with few exceptions such as the impact by the immigrated ctenophore Mnomiopsis leidyl. Here we describe the association of the invasive cirripedian crustacean Balanus improvisus and the cheilostomate bryozoan Conopeum seurati with the limnocardiid bivalve Didacna sp. endemic to the Caspian Sea. The description represents only the first step towards an understanding of the interactions between the invasive and endemic species.