Our means of simulation could be used for other species, both marine and freshwater, e.g. the data for the copepod Boeckella triarticulata ( Twombly & Burns
1996) like those from Klein Breteler (see section 2) could be used to test the model. The next step in our studies will be to determine the egg production by female of T. longicornis based on the hypothesis that the food-saturated rate of production of egg matter is equivalent to the specific growth rate. The copepod model will be calibrated for T. longicornis under the environmental conditions typical of the southern Baltic Sea, including the influence of salinity as a masking factor on its development. Another step in our work is to run the population model within an ecosystem model check details ( Dzierzbicka-Głowacka NU7441 et al. 2010a) to study the impact of seasonal variations of food and temperature as well as salinity on the T. longicornis biomass in the southern Baltic Sea. “
“In recent years both rare (or visiting) and exotic species have been recorded in the southern Baltic and its estuaries, e.g. sea bass Dicentrarchus labrax (L., 1758), saithe Pollachius virens (L., 1758), ballan wrasse Labrus bergylta (Ascanius, 1767), snake pipefish Entelurus aequoreus (L., 1758), Atlantic mackerel
Scomber scombrus L., or swordfish Xiphias gladius L., 1758 ( Krzykawski et al., 2001, Bacevičius and Karalius, 2005, Grygiel and Trella, 2007, Lampart-Kałużniacka et al., 2007 and Czerniejewski et al., 2008). The present paper reports the first occurrence of striped red mullet (or surmullet) Mullus surmuletus L., 1758, in the Pomeranian Bay in 2007 and the occurrence of three very rarely noted species – tub or yellow gurnard Chelidonichthys lucerna (L., 1758), Atlantic horse mackerel Trachurus trachurus L., 1758 and thicklip grey mullet Chelon labrosus (Risso, 1827) – caught in the Pomeranian Bay, Szczecin Lagoon and Lake SB-3CT Dąbie in 2007–2008. The striped red mullet is a new species
found in the Pomeranian Bay, whereas the other three species are known from single finds and apparently belong to the category of accidentally occurring fish. The presence of these species in the Pomeranian Bay and adjacent waters (Szczecin Lagoon, Lake Dąbie) is probably due to strong inflows of saline water from the North Sea through the Danish Straits, as well as to climate changes (Nausch et al., 2007, Nausch et al., 2008 and Matthäus et al., 2008). The Baltic Sea’s environmental conditions and their variability are closely linked to the hydrological and meteorological processes and their interactions, among other things (Grygiel & Trella 2007), while the climate and hydrology of the Baltic Sea region is influenced by the winter intensity of the North Atlantic Oscillation NAO (Lehmann et al. 2002).