Volume 36 (2007): Issue 2 (June 2007)

The spatio-temporal variability of mesozooplankton in the Gulf of Gdańsk was studied using samples collected in the western part of this basin every month in the 1999-2000 period. The investigation indicated that the qualitative composition of zooplankton was typical of this area and was comprised of Copepoda, Cladocera, Rotatoria, Appendicularia, and meroplankton. Acartia bifilosa and Temora longicornis were present permanently, while Cladocera, Acartia tonsa, Centropages hamatus, Eurytemora sp., the genus Keratella, as well as Mollusca and Balanus improvisus larvae exhibited clear preferences for warmer months. Acartia longiremis, Pseudocalanus elongatus, and Fritillaria borealis were encountered in the cooler season (from November to April). Synchaeta spp. dominated among Rotatoria and Polychaeta larvae among meroplankton. The presence of Brachionus calyciflorus indicated the presence and influence of riverine water from the Vistula.

The purpose of the presented paper is the identification and assessment of causes of intensive abrasion in the open coastline of the Hel Peninsula and the effect of countermeasures. Numerical modeling of nearshore hydrodynamics, topographic analysis and field measurements were carried out. The Baltic Sea hydrodynamic model, a model of wave-induced nearshore circulation and the wave model SWAN were employed. 3D hydrodynamic modeling resulted in the become visible that fields of shear bottom stresses as well as bottom currents depended on atmospheric forcing and depth. A correlation between bottom stresses and topography was obtained. The results of modeling of the nearshore hydrodynamics demonstrated a dominant role for alongshore sediment transport. The magnitude of both cross-and alongshore wave-induced currents strongly depended on wave height gradient, which was significantly greater in storm periods. During storms, sediment transport occurs also in the cross-shore direction.

The broad-nosed pipefish (Syngnathus typhle) is a species considered threatened with extinction on the Polish Baltic coast. The presence of S. typhle in the Gulf of Gdańsk was investigated primarily by means of scuba diving, and the species was recorded at 12 of 20 sites, which were investigated. A total of 85 individuals were found. The highest numbers were observed near the mouth of the river Płutnica and near the pier in Sopot. Pipefish were found in bottom areas covered with green algae (Cladophora sp. and Enteromorpha sp.) and brown algae (Pilayella sp.), but not by vascular plants as was previously reported.

This work presents the community composition, abundance and seasonal dominance of phytoplankton taxa in three hydrochemically different, mid-forest humic lakes. The largest number of taxa was observed in the oligohumic lake (76), with smaller numbers seen in the mesohumic (42) and polyhumic lakes (37), which were characterized by higher contents of dissolved humic substances carbon (DHSC). Along an increasing gradient of DHSC in a pool of dissolved organic carbon (DOC) the autotrophic algae were seen to disappear, being replaced by taxa with features of facultative heterotrophs and flagellated algae that are able to move in the water column.

In particular branches of the Earth sciences the term estuary is used with various meanings. The term estuary is applied to objects that often differ from the original geographic meaning of the word. The phenomena that accompany them and processes that cause them are called also estuary phenomena and processes. The aim of the study is to describe, in a geographic context, the range in meaning of both the term and names of phenomena and processes derived from it. In the years 2002 - 2005, a survey of the distribution of chloride concentrations was conducted on five lakes characteristic of the southern Baltic coast: Jamno, Bukowo, Wicko, Kopań and Łebsko. It was observed that seawater intrusions into the coastal lakes only resembles those that occur in classic estuaries, though the results are similar to seawater intrusion processes. In the Polish section of the southern Baltic coast, coastal lakes are not the only places where these phenomena are observed. We suggest that all inland water bodies that are under the influence of marine intrusions should be called coastal waters, instead of the misleading term estuary.

The aims of this study were to identify the taxonomic and trophic diversity of planktonic ciliate communities occurring in small peat-bog reservoirs of various acidities (from about 3 to 6), and to assess the effects of chemical factors on them. Generally the highest numbers of ciliate taxa were recorded in high pH (>6) reservoirs, and the lowest in low pH (3.28-4.6) reservoirs. The mean numbers of planktonic ciliates in the high pH reservoirs were about three times higher than in the low pH reservoirs. However, the greatest biomass of ciliates occurred in low pH reservoirs.

The results suggest that pH, conductivity and total organic carbon (TOC) are more important than total phosphorus (P_tot) in the distribution of planktonic ciliates in peat-bog reservoirs. In the low pH peat-bog reservoirs, the biggest factor affecting ciliate distribution is the pH of the water, whilst in the higher pH reservoirs the role of organic matter becomes increasingly important with increasing pH.

The authors find no arguments that would justify application of the term "estuary" to the area of the Odra River discharge into the Baltic Sea. The physiography, geology, and hydrology of the Odra river mouth show that the area possesses many more characteristics typical of flow-through coastal lagoons than those of estuaries. Of key importance in this respect is the Szczecin Lagoon, an extensive, shallow water body separated from the open sea by a barrier intersected by three narrow and long straits. The lagoonal nature of the area is demonstrated also by its geological history.

Estuaries are areas where river and sea waters meet. Therefore, the hydrodynamical, hydrochemical, and hydrobiological processes in the estuaries are typical for both environments. The most important processes, which play leading roles in estuaries include the dynamics of water flow, water quality, and the mixing of water of different biochemical characteristics. This paper is divided into two parts. In the first, basic hydrodynamical processes are described and analytical and numerical methods of evaluating them are presented. Part two illustrates these processes using experimental data and the results of mathematical modeling for some estuaries along the Polish Baltic coast.