engleski

Preliminary study of the zooplankton of the Albanian coastal and open sea during May 2009

We present for the first time composition, numerical abundance and the vertical structure of micro- and mesozooplankton in Albanian coastal and open-sea region. Zooplankton was sampled at six stations on the 75 km long shelf-continental slope transect. The most numerous microzooplankton were copepod nauplii (maximum: 39 individuals per litre), followed by calonoid and cyclopoid copepodites (maxima: 5 and 4 ind.L-1, respectively). According to the Mann-Whitney U Test, higher nauplii values were found in surface layers (0 and 5 m). Among fourteen tintinnid species, the most abundant was open-sea species Tintinnopsis radix, found in the surface to 50 m layer, from the coastal to the 300-m-deep station. The maximum of 36 ind.L-1 was at A-300. Other tintinnids, though less numerous, also reflected influence of open-sea water at the coastal stations, as well as the transport of the surface lower salinity coastal waters to the open sea. Mesozooplankton diversity rose considerably from the coast the open sea. Mesozooplankton abundances exhibited the opposite trend, with the maximum (2 569 ind.m-3) noted at the most shallow station. Copepods contributed between 80 - 98% of total mesozooplankton abundance. Oithona similis was the dominant species at all stations, followed by Paracalanus parvus and Acartia clausi at the shallower coastal stations and Clausocalanus pergens, Ctenocalanus vanus, O. plumifera, and Mecynocera clausi offshore. These initial results suggest the low influence of fresh water on zooplankton population densities. Totals for micro- and mesozooplankton were typical for coastal and open sea areas of the oligotrophic Southern Adriatic, even at the shallow stations, where penetration of fresh water in the surface layers was notable.

microzooplankton; mesozooplankton; species diversity; indicator species; Southeastern Adriatic Sea; Drini Bay; Albania

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