HOT-SPOT AREAS OF BENTHIC NONINDIGENOUS SPECIES IN THE ADRIATIC SEA (CROATIA)

Number of marine benthic NonIndigenous Species (NIS) in the Adriatic Sea (Croatia) is constantly increasing. Some areas stand out by higher number of recorded NIS. Such HOTSPOT areas are the southern part of the Croatian coast, wider area of Split and tuna fish farms on Brač Island. By analysing biological features of the recorded NIS, possible vectors of introduction and secondary spreading and ecological features of the invaded areas, we attempt to answer the following question: is elevated number of NIS in some areas a result of: 1) spreading of NIS by currents ; 2) transport by shipping ; 3) susceptibility of the area for NIS establishing ; 4) level of area surveillance ; 5) combination of different factors. We speculate how the majority of NIS are introduced in Croatian by currents (by the main Adriatic current from the Ionian Sea) and by shipping. Secondary spread through the Croatian coast is dominantly a result of propagule spreading by currents. Establishment of NIS is in many situations result of some form of ecological disturbance, like pollution and eutrophication such as area of tuna-fish farms or sewage outfall.