engleski

Juvenile fish assemblages in the Zadar area (eastern Adriatic Sea, Croatia), spatial and temporal patterns of settlement and habitat use ; a preliminary approach

Spatial and temporal patterns of distribution and abundance were examined for post-settlement fish assemblages collected from different habitats in the Zadar area, Croatia. The specimens were caught using a small beach seine at six stations from samples taken on May and June 2017. Most diverse family were Sparidae comprising 8 species, followed by Gobiidae with 7 and Labridae with 4 species. The most abundant juvenile taxa were the atherinid Atherina boyeri accounting with 77.27% of the total catch. Differences in fish assemblages were observed with respect to sampling dates and station mostly due different temporal and spatial distribution of settlers. Studied juveniles settled to well defined habitats with characteristically distinctive substrate types. Sparid species settled primarily in the shallowest zone (0 to 3 m), and most of them prefer varied bottoms (sand, gravel or rocky ; vegetated or unvegetated). Labrid species are normally found on rocky substrates with high algal cover, while atherinids show no clear link with the substrate type. Species richness was significantly higher in well structure habitats (i.e. vegetated areas), as well as differences in abundance and biomass of fishes between vegetated and unvegetated habitats depended on the location of sampling. In general, abundance and biomass in the vegetated areas were higher than in unvegetated habitats. Marine nursery is defined as a juvenile habitat for a particular species that contributes a greater than average number of individuals to the adult population when compared to other habitats used by juveniles. For many fishes these areas are found in/or restricted to coastal shallow-waters with structurally complex habitats. Such locations generally are highly productive and afford protection to smaller fish by restricting access and/or impeding the foraging capability of piscivorous fish predators.

infrallitoral fish assemblages, nursery areas, juveniles, distribution, habitat

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