A benthos survey of the Senj Archipelago (North Adriatic Sea, Croatia)

Abstract

          The coastal seabed around the northern Adriatic islands of Prvić, Sv. Grgur, and Goli have remained little researched until recently. Therefore, we compiled here results of our studies on macroflora, fauna, and bottom communities. The benthos was surveyed by scuba diving at 26 sites and a fish census taken at 14 of them. Bottom trammel nets were used at 15 sites to document the structure and status of fish populations. Deep deposits were sampled by bottom grabs at 27 sites.
         Fifty-six species of macroalgae, two marine phanerogams, 218 invertebrates, and 96 fish species were recorded. The most significant hard bottom communities were the biocoenosis of infralittoral seaweeds and the coralligenous biocoenosis. Deep deposits were characterized by elements of the biocoenoses of coastal terrigenous ooze and bathyal silts. Due to hydrodynamic conditions, there was a spatial mixture of populations peculiar to various communities. Scuba diving is a very suitable method for rapid identification and evaluation of infralittoral benthos. However, fish assemblages can be satisfactorily estimated only by compiling diving records and analyzing fishing gear catches.
         Although results of our research reflect the study methods, it is evident that the benthic communities and fish assemblages in this area are very diverse and well preserved. Therefore, we again propose protecting the Senj Archipelago coastal seabed within the category of a special marine reserve, i.e. marine park.