engleski

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

Zooplankton was sampled at six stations along a transect from the Albanian coast (41º 41’ N, 17º 21’ E) to the open sea (41º 24’ N, 18º 32’ E). Microzooplankton was collected with a Niskin bottle at several depths and passed through a 53-µm mesh net until the original volume of 5 L was reduced to 250 ml. Mesozooplankton was collected with either a 125-µm (coastal stations) or 200-µm (open-sea) Nansen opening-closing net. Among fourteen tintinnid species, the most abundant was Tintinnopsis radix, found in the surface to 50 m layer, from the coastal to the 300-m-deep station (A-300). The maximum of 36 ind.L-1 was at A-300. Other tintinnids, though less numerous, reflected a strong 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. The most numerous microzooplankton were copepod nauplii (maximum: 39 ind.L-1), 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). There were no significant differences among microzooplankton abundances between stations. Mesozooplankton diversity rose considerably from the coast the open sea. Mesozooplankton abundances, on the other hand, exhibited the opposite trend, with the maximum (2569 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; Albanian sea

nije evidentirano