9 Spatio-Temporal Distribution of Mediterranean Cold-Water Corals

Abstract

Cold-water corals have inhabited the Mediterranean basin since at least the Miocene, undergoing important modifications through time. Most information regarding pre-Pleistocene occurrences of extant cold-water coral species still relies on ancient literature records in need to be updated according to modern taxonomic and chronostratigraphic concepts. In this chapter, Neogene and Quaternary coral records are discussed. Many occurrences have been revised from the taxonomic point of view through the analysis of historical museum collections, newly collected specimens and original species descriptions and illustrations. In particular, this study summarises the current state of knowledge on Mediterranean frame-building cold-water corals and associated solitary species from the Miocene onwards. Several growth and demise phases, as well as changes in composition of dominant species have been observed so far. A shift from Dendrophyllia- to “Atlantic-like” Lophelia-dominated paleocommunities occurred at the Pliocene – Pleistocene boundary. “Golden ages” for the species Lophelia pertusa, and large bioconstructions formed by this coral, are thus far known in the Early Pleistocene (Calabrian stage), at the boundary Bolling- Allerod – Younger Dryas and in the Early Holocene (at least in the western basin). A large knowledge gap currently exists between the end of the Calabrian stage and the last 50 kyr BP. Several Atlantic deep-sea species (including frame-building and “psychrosperic” cold-water corals), common in the Early Pleistocene, disappeared in the Mediterranean after the Late Pleistocene, but how and when this event occurred is not known yet. Further studies need to be carried out to understand if there is any correlation between this deep-sea basin-scale extinction and the decline of Lophelia-dominated bioconstructions observed in the late Younger-Dryas and after the Early Holocene. In order to fill knowledge gaps on the fossil record of Mediterranean cold-water corals and to fully exploit the valuable potential of these organisms as palaeoenvironmental archives, the setup of a comprehensive open access database, including quality-controlled data on both modern and fossil species, is highly recommended. This would also provide a useful tool for managing, valorising and preserving the unique, yet undervalued paleontological heritage of the Mediterranean regions.