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Changes in the basic physical properties of selected areas of the Baltic Proper were analysed on the basis of the results of a 12-year series of high-resolution measurements collected during cruises of r/v ‘Oceania’. The high-resolution CTD sections covered three main basins: the Bornholm Basin, Słupsk Furrow and Gdańsk Basin. Positive temperature trends of 0.11 and 0.16◦C year−1 were observed in the surface and deep layers respectively. The salinity trend was also positive. The rise in the air temperature has probably caused the increase in surface water temperature, while advection has been of greater significance in the deep layer. The increase in salinity coincides with the more frequent occurrence of small and medium-size inflows through the Danish Straits, even though large inflows are evidently less frequent than used to be the case. The seasonal variability of temperature in the water column was analysed. The phase shift in the seasonal evolution with depth is described. The maximum temperature shift in the waters investigated varies from 32 to 38 days.
W pracy przedstawiono w formie syntezy identyfikację i analizę struktury przestrzennej uwarunkowań wodnych zlewni Raszynki (po profil Dawidy) na potrzeby planowania przestrzennego. Podstawą metodyki pracy jest wydzielanie homogenicznych jednostek przestrzennych o różnym poziomie złożoności. Każda z nich, w zależności od kryteriów wyróżnienia i stopnia agregacji, w różnym stopniu oddziałuje na mały obieg wody. W zlewni Raszynki do profilu Dawidy zidentyfikowano duże zróżnicowanie przestrzenne homogenicznych jednostek reżimu wodnego. Usytuowane są one przeważnie w układzie płatowo-pasmowym i pasmowym, równoległym do doliny, co wskazuje na złożone i zmienne przestrzennie warunki wodne w zlewni.
Apart from their basic role as fish farming reservoirs, carp ponds have an important influence on water circulation and thus on water resources in the catchment basin. The positive influence of carp ponds as storage reservoirs results from the rearing cycle which corresponds with the hydrological cycle and consists in limiting high water-flows in the summer and increasing low water-flows in the autumn. After the maximum precipitation shifted in the late 1960s from summer months to autumn months, a dramatically low water level occurred in the summer. This highly disturbed the catchment basins’ hydrological balance as well as the ponds’ water management. The influence of the changing meteorological conditions on individual components of the water balance are presented as a result of many years’ research (1957-1997) conducted at the Institute of Ichtyobiology and Aquaculture of the Polish Academy of Sciences in Gołysz.
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Estuaries - types, role and impact on human life

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Estuaries are transition zones between the land and the sea which form aquatic ecosystems, often referred to as marginal filters. Numerous classifications of estuaries are based on such criteria as: geomorphological structure, the character of water circulation and stratification, the ratio between freshwater and marine water and the type of energy flow. However, not all estuaries fall into one of the above categories. Some of them represent an intermediate type, while the type of others may change depending on the season and related changes in water inflow rate. Fisheries, including bi-valve mollusks, depend on the high productivity of estuarine areas, which can be also used as ports or sites of recreation and industrial activities. Estuaries play a fundamental role in maintaining an ecological balance in the biosphere.
Twelve consecutive seasonal surveys were carried out in Klaipeda port, Lithuania, in 2006-08. Water parameters such as temperature, pH, salinity, dissolved oxygen, particulate material, nutrients (N/NH₄⁺, N/NO₂⁻, N/NO₃⁻, P/PO₄³⁻), petroleum hydrocarbons, and heavy metals (Cu, Zn, Ni, Pb, Cr, Cd, Hg) were determined in both the surface and near-bottom water horizons. Total contamination of port waters was evaluated and the patterns of seasonal and spatial contamination patterns revealed. It was determined that the level of water contamination in Klaipeda and its separate water areas depends on the input of pollutants from the Curonian Lagoon basin and local sources, water circulation patterns, and seasonal dynamics of water parameters. As Klaipeda is in a zone of circulation and maximal interface of fresh (from Curonian Lagoon) and saline (Baltic Sea) waters, its water pollution is associated with the dominant type of water. The highest levels of pollution, in combination with the highest water temperatures, highest concentrations of particulate material and smallest concentrations of O₂, occur in summer, when heavy metals, lead in particular, are the dominant pollutants in the water.
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