Oceanologia (Jun 2003)
Short-term and seasonal variability of mesozooplankton at two coastal stations (Gdynia, Sopot) in the shallow water zone of the Gulf of Gdańsk
Abstract
The idea of the study was to describe short-term and seasonal variationsin the composition and abundance of zooplankton in the coastal area of theGulf of Gdansk at two shore stations and the influence of selectedenvironmental factors (temperature, salinity, wind velocity) on it. The studieswere based on material collected in the shallow waters of the Gulf of Gdanskfrom stations located by the Marine Promenade (Bulwar Nadmorski) in Gdynia andthe pier in Sopot. Samples were collected in 2001 mainly at weekly intervalsusing an open-type plankton net. Environmental parameters were measured at thesame time. The zooplankton at the Gdynia and Sopot stations consisted of30 taxa; Rotatoria, Copepoda and meroplankton were dominants.There was a much higher percentage of Rotatoria and a lower percentage of meroplankton at Sopot than at Gdynia. Considerable differences were apparent in the numbers ofparticular groups of zooplankton at these stations in the same periods.Simpson's biodiversity index, here based on the zooplankton of the shallowwaters off Gdynia and Sopot, was relatively high most of the time.Diversity of mesozooplankton was greatest in July and October. There was a significantcorrelation between the abundance of mesozooplankton and environmental factorsin the case of cladoceran and polychaete larvae. Frequent studies at stationslocated close to each other illustrate the highly dynamic range of variationsoccurring in the coastal area: the concentrations of particular organismsfluctuated very considerably from one week to another, even by a factor ofseveral dozen. Nevertheless, the statistically mean numbers of zooplankton atboth stations are comparable.
