Within a small (2.5 x 2.5 km) test field, located in the eastern part of the Pomeranian Bay, the geological structure was investigated in detail using seismoacoustic profiling and coring. In the cores, mineral grain size and micro- and macrofauna were analysed. Basing on seismoacoustic records, three main seismostratigraphic units were distinguished. The lowest unit is built of sand and muddy sand. Higher up lies the unit of sandy mud, in some places - of clay. Fauna assemblages indicate cold climate conditions, and clearly point to an existence of lacustrine reservoir of oligotrophic character. Analysis of cores shows that sedimentation began in bog conditions. The lakes in the area existed till the Atlantic period, when due to sea transgression they became filled with sandy sediments. The third unit is built mainly of fine sand, locally medium sand, even with addition of gravel. Basing on the presence of marine fauna, this unit is classified as marine sand.

This article presents results of the analysis of 3 sediment cores taken from the bottom of Pomeranian Bay, southern Baltic Sea. These results are part of a larger project that aims to determine the characteristics and rate of the Atlantic marine ingression in the Pomeranian Bay area. The main geochemical elements and diatom assemblages from the cores were identified, revealing lacustrine sediments deposited during the time of Ancylus Lake and marine sediments deposited during the Littorina transgression. Distinct changes in the geochemical composition and diatom assemblages suggest that the Littorina transgression had a very large impact on the environment of Pomeranian Bay.

Round goby (Neogobius melanostomus (Pallas, 1814)) is an invasive species in the Oder River. In this study, age of 147 fish was determined using scales and otoliths, and the Fraser-Lee back-calculation method was used for population structure and theoretical length growth rates with 3 mathematical models of growth: von Bertalanffy, Ford–Walford and 2nd degree polynomial. Fish condition was determined using Fulton, Le Cren and Clark equations. Average total length and weight of fish was 162.00 mm and 83.00 g, respectively. Males were more abundant than females, representing 70% of the fish caught, and achieved greater total lengths and weights. Age 2+ dominated females and 3+ males age groups. Of the three mathematical models used to estimate fish growth, the 2nd degree polynomial model had the best fit to back-calculated lengths. Males had slightly higher growth rates than females in the first two years of life but comparable in subsequent years. The diet consisted of various benthic organisms that varied with fish age. The most frequently occurring food com-ponent was Dreissena polymorpha, which accounted for approximately 70% in the diet of fish with a body length greater than 191 mm.