43 The Spread of Non-indigenous Species in the Mediterranean – A Threat to Cold-Water Corals?

Abstract

Only few live records of cold-water corals are known from the Aegean and Levant seas, though antipatharians, ceriantharians, zoantharians, gorgonians and pennatulaceans have been recorded from their continental shelf and upper slope. These mesophotic coral communities, including the Corallium rubrum (Linnaeus, 1758) colonies in Crete and southeast Turkey, are already within the depth range of disruptive carnivorous and omnivorous non-indigenous species introduced though the Suez Canal. The recent enlargement of the Suez Canal has raised concern over increasing propagule pressure of deeper living species. In fact, the recently observed “descent” of Erythraean non-indigenous species from the upper to lower continental shelf and upper slope may be also a harbinger of temperature-dependent range expansion, both horizontal and vertical. As mesophotic coral communities in the easternmost Mediterranean have barely been documented, it is impossible to predict the possibility of degradation and loss of native populations, habitats and ecosystem services. However, preliminary studies on impacts of the invasive Indo-Pacific lionfish on Caribbean mesophotic reef communities suggested a shift in community structure. The spread of non-indigenous species to mesophotic depths requires a concerted effort to map these habitats and study their communities.