After a century in the Mediterranean, the warm-water shipworm Teredo bartschi invades the Lagoon of Venice (Italy), overwintering a few degrees above zero

Abstract

During almost a century of permanence in the Mediterranean, the warm water species Teredo bartschi has adapted to progressively colder climates up to overwintering at water temperatures only a few degrees above zero. A fine-grained analysis of discoveries, synonyms, museum collections and grey literature establishes that this species entered the Mediterranean since at least 1935. Coming from tropical waters through the Suez Canal, the species has undergone to a long period of acclimatization in the Levantine Basin of the Mediterranean and then pushed north at the beginning of this century until it has invaded the Lagoon of Venice. The invasion routes are reconstructed and presented. The lagoon of Venice is a microtidal bar-built estuary located in the northernmost part of the Mediterranean and represents the highest latitude reached by the species on a global scale. Here for over ten years, T. bartschi has now become invasive forming stable and abundant populations. This paper presents some biometrics of hard parts such as pallets and shells as well as the description of siphons, useful for the identification and characterization of the species. The shape of the pallets of the Venetian population differs from the Aqaba’s (Giordania) and Mersin’s (Turkey) populations. Phenotypic variation are probably due to environmental effects on morphology.