engleski

Was enhanced riverine input responsible for the demise of Central Adriatic cold water reefs in historical times?

Shallow buried cold-water coral mounds occur in the middle part central Adriatic in the area of Pomo/Jabuka Pit (or Middle Adriatic Pit/Depression) at ca. 200 m water depth. Marine geophysical data (multiswath bathymetry, chirp and side scan sonar profiles), ROV and seabottom samples were obtained from this area in December 2008 during cruise ARCO of RV Urania. These mounds are characterized by the frame building scleractinians Lophelia pertusa and Madrepora oculata, at places associated with Dendrophyllia cornigera, while the solitary coral Desmophyllum dianthus is uncommon. Cores taken from the mound area reveal that coral mounds grew over a late Pleistocene (glacial) sedimentary substrate and are at present buried under a veneer of mud. The base of an individual 40 cm thick coral mound cored at 45°53.3’ N-15°05.6’ E (st. ARCO54: depth 206 m) was AMS-C14 dated at 5400 cal years BP while the top of this same coral mound provided an age of 1600 cal years BP. The mound is draped by ca. 15 cm of mud. Our evidence indicates that well structured deep water coral reefs were established in the central Adriatic at depths that are shallower than the modal bathymetric distribution of such corals in the Mediterranean and Atlantic. Moreover they were alive until few centuries ago, basically at late times of the Roman Empire. Their (sudden?) demise is possibly linked to a dramatic silting event, a case already documented in other Mediterranean sites (Alboran, Tyrrhenian) although older since dated at the transition from glacial to postglacial conditions. Enhanced silting in the study area could have been the result of higher turbidity events linked to the Po and other Apenninic rivers induced by climatic or anthropic causes.

deep sea white coral mounds; Middle Adriatic Depression; climatic changes

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