engleski

Ecology of an anchialine cave in the Adriatic Sea with special reference to thermal regime

Anchialine habitats are coastal caves flooded with seawater which fluctuates with the tides, but with no surface connection to the sea. The ecology and thermal regime were studied in the anchialine cave Ziva voda on Hvar Island (Adriatic Sea, Croatia). Since Ziva voda cave has no direct connection with the open sea, both speleological and SCUBA diving methods were applied. Inside the cave, a dense population of the hexactinellid sponge Oopsacas minuta Topsent, 1927 has been recorded. Polychaetes, molluscs and crustaceans were found as well. Two-year temperature data recorded simultaneously at two depths within the cave and at a nearby sea location revealed the thermal conditions in the system. The temperature oscillations within the cave are strongly dampened. The temperature varyes from 14.6 0C in winter to 17.9 0C in summer, the annual range being four times smaller than in the adjoining sea. This seawater temperature onside the cave challenges the commonly held assumption that the hexactinellid sponge O. minuta is able survive in the coastal zone only in cold-water regions.

nchialine cave; thermal regime; Adriatic Sea

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