engleski

A marine benthos survey in the Jezera of the National park Mljet (Adriatic sea)

A lake-like inlet named Jezera is the most known phenomenon of the National park "Mljet", occupying the western part of this southernmost large island of the Adriatic Sea. The Jezera are virtually two depressions overfloaded by the sea in the postglacial period. Although the Jezera are considered an attractive natural little studied phenomenon, their environmental and biological characteristics have not been studied until recently. The benthic ecosystem, its fauna and flora, and especially communities distributional patterns is insufficient know. The supralittoral and mediolittoral zones, and infralittoral fringe were analysed visually applying a modified phyto-sociological method. In situ observations of infralittoral and circalittoral zones, were fulfilled by SCUBA divers with applied underwater photography. Bottom deposits were sampled by divers with a hand corer. The sediment living macrofauna was collected with a hand grab. In spite of special environmental conditions the marine flora and fauna of the Jezera inlet is very diverse and some taxa are very abundant. Some 315 species of macroflora and macrofauna were identified, more than a half of them being noted for the first time in the area. Eight benthic biocoenoses were identified, some of them exhibiting a belt-like distribution. In comparison with the communities distribution along the open sea coasts of the Mljet Island, the biocoenoses of photophilic algae, and the coralligenous bottom are much depressed in the inlet, and Posidonia ocenica beds are absent. Field surveys proved that the law-protected pen shell (Pinna nobilis) and the great scallop (Pecten jacobeus) populations in the Jezera inlet have a much wider distribution than it was supposed earlier.

marine benthos; ecology; national park; Adriatic Sea

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