engleski

Impacts of different kinds of harbor pollution of the city of Rovinj (Croatia, northern Adriatic Sea) on polychaete fauna

Polychaetes are, considering their abundance, species richness and functional diversity, the most important macrobenthic group in soft bottom benthic communities and can be considered as representative group in describing their diversity and dynamics. They are also proven to be very good indicators of natural and anthropogenic stress in benthic communities. The aim of this research was to estimate the impacts of different harbor pollution on benthic communities of the city of Rovinj (northern Adriatic Sea, Croatia) by accessing the composition and structure of polychaete assemblages. Samples were taken in two harbors subject to different kinds of pollution and compared to those taken on two control stations. Harbor 1 is influenced by high organic load coming from the discard fish thrown from the commercial fisherman’s boats as well as from the fish factory waste water discharge ; harbor 2 is shallow sheltered city harbor influenced by the pollution from hundreds of harbored recreational vessels and artisanal fisherman’s boats. In each port three sampling stations were chosen, while two control stations were situated in the area not influenced by the harbor pollution. At each station soft bottom samples were taken by Van-Veen grab (0, 1 m2) in four replicates, sieved through 1 mm mesh size, fixed in 4% buffered formalin and after sorting preserved in 70% ethanol. Polychaetes were determined to the species level. Structure of polychaete assemblages was analyzed by multivariate techniques (Primer, Plymouth). Altogether 162 polychaete species were found. Diversity (number of species and Shannon-Wiener index), abundance (number of individuals) and Pielou’s evenness index were the highest in the polychaete assemblages within the harbor 1 subject to fisheries waste discharge indicating favorable effects of organic enrichment on both diversity and abundance of polychaete fauna. The lowest abundances and number of species were found within the harbor 2 indicating that this kind of harbor pollution might have negative impacts on the analyzed communities. Cluster analyses indicated higher similarity (Bray-Curtis) of the polychaete fauna from the control stations and harbor 1, while polychaete fauna from the harbor 2 seems to be more different from the other two. Observed differences might also be due to the granulometric composition of the sediment influencing polychaete assemblages. SIMPER analyses indicated polychaete species mostly characterizing different sites. The species greatly characterizing both harbor sites but absent on the control ones is Capitella capitata, typical indicator of disturbed environment and organic enrichment. Other polychaete species indicators of organic enrichment such as Sigambra tentaculata, Polygordius triestinus, Paradoneis lyra and Cirrophorus furcatus were also representative of harbor stations. Our results indicated that harbor pollution on two investigated sites did not cause disastrous changes in the polychaete assemblages such as drastic drop of species diversity or abundance but it influenced assemblages’ composition and structure favoring the development of polychaete fauna compound of many tolerant species typical for polluted environment.

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