Interaction of non-native bivalves and exotic dendrophylliid corals (Scleractinia, Dendrophylliidae) in the Brazilian Northeast coast

Biological invasions are considered one of the major concerns of conservation policies worldwide, with the introduction of exotic organisms in coastal environments threatening marine biodiversity.Indeed, mollusks are among the top invertebrates introduced around the planet, with snails and bivalves transported out of their original geographical area through human activities.With great invasive potential, bivalves can cause cascading impacts, altering the structure, and processes of the benthic assemblages.Intending to assess the distribution and associated fauna of exotic dendrophylliids in the Todos-os-Santos Bay (12S), Southwestern Atlantic, marine mollusks were identified.From 2020 to 2022, corals were monthly collected, and examined individually, in two populations on pier decks and columns.Colonies prevailed on carbonate substrates, majorly fixed on alive barnacles and bivalves, being also observed on vermetids, ascidians, and sponges.The identification of the bivalves provided evidence of the interaction between 'sun corals' and two other introduced organisms in the TSB: Saccostrea cuccullata and Isognomon bicolor.All bivalves were apparently healthy, with the soft tissues intact.For the first time, it is described as a case of epibiosis between bivalves (basebionts) and scleractinians (epibionts).