engleski

Fish-farming effects on meio- and nematofauna diversity in Limski zaljev (Northern Adriatic Sea, Croatia)

This presentation concerns the long-term and the short-term impact of intensive fish farming on meio- and nematofauna assemblages in Limski zaljev. Due to its geomorphologic value, as well as its beneficial for fish over-wintering and spawning Limski zaljev is Protected Landscape since 1964 and Special Marine Reserve since 1980. It is sheltered and semi-enclosed bay with low water exchange and muddy bottom. Except the mariculture, all human activities are suppressed. Intensive mariculture has started in the second half of the 80ies, following installation of five commercial farms for cultivation of Dicentrarchus labrax L. and Sparus aurata L. Farms were situated in the inner part of Limski zaljev until October 2006 when they were dislocated about 1 km seaward. In order to assess the long-term impact meio- and nematofauna assemblages were studied in the area exposed to fish-farming impact over 20 years. Samples were collected at 5 sites underlying the fish farms and 2 referent sites at 20 meters and 1 km distance from the farming area. Samples were taken in two contrastive periods (summer vs. winter) related feeding rate and biodeposition. A short-term impact was studied within new farming area and samples were taken prior to cages deployment and then one month, six months and one year later. All sites characterized by similar depths (20-31 m) and clayey-silt sediment (95-99% silt and clay fraction). At all sites meiofaunal assemblages dominated by nematodes, but differ in taxonomic composition and richness, as well as in diversity of nematode species. Results suggested significant differences in meio- and nematode assemblages structure between impacted and reference sites relating to both the long-term and the short-term effect. However, the results suggested a localized environmental impact that is restricted to the perimeter of the farm. In conclusion, despite to local effects on meiobenthos fish farming in the Limski zaljev is considered to be eco-sustainable.

mariculture; meiofauna; nematodes; Limski zaljev bay; northern Adriatic

nije evidentirano