The diet of otters Lutra lutra was studied by spraint analysis in six river and stream habitats in eastern Poland. In all of them fish were the staple food of otters, constituting from 29 % to 96 % of prey consumed in particular seasons. In upland (river Tanew) and mountain (river San, streams Dwernik and Głęboki) habitats, bullheads (Cottus gobio) were the most frequently eaten fish throughout the year (with maximum contribution of 57 % in the winter diet on river Tanew). In these habitats otters preyed on total of 10 fish species, including: brown trout (Salmo trutta), stone loach (Barbatula barbatula ), brook minnow (Phoxinus phoxinus) and stickleback (Gasterosteus aculeatus). On the lowland rivers, otters relied on more fish species than on the upland and mountain rivers (14 species on river Czarna Hańcza and 12 species on the upper and lower course of river Biebrza). Beside various cyprinids, otters preyed on stickleback, perch (Perca fluviatilis), mud loach (Misgurnus fossilis), burbot (Lota lota) and pike (Esox lucius). On all rivers, except the lower Biebrza, most of fish (from 70% to 88%) captured by otters were less than 10 cm long. Amphibians and crayfish were two other important groups of prey. On small streams in the Bieszczady Mountains, frogs (mainly Rana temporaria) comprised up to 46% of otter prey. Crayfish (Ortonectes limosus) remains were recorded in otter spraints only on the lowland rivers: in summer crayfish comprised 52% of prey on the Czarna Hańcza River and 47% of prey on the upper Biebrza River. In upland and mountain habitats the food niche breadth of otters was lower (from B=2.62 to B=6.12) than on the lowland rivers (from B=3.10 to B=11.09) and did not differ much between the seasons. On the lowland rivers the food niche breadth was high in winter and low in summer, and the seasonal differences in otter diet were much more pronounced as compared to the upland and mountain habitats.
Škeblička plochá (Pseudanodonta complanata), dříve škeble plochá, se v České republice vždy považovala za vzácného a především řídce se vyskytujícího mlže, a to i v tocích málo ovlivněných člověkem. V současnosti je znám výskyt škebličky v povodí Dunaje z Dyje a z Moravy těsně nad ústím Dyje, ojedinělý nález pochází i z Malé Bečvy. V povodí Odry byla zaznamenána pouze z vlastní Odry. V povodí Labe je výskyt častější a lze ji stále nalézt v již zmiňované Orlici, Lužnici a Nežárce, dolní Otavě, dolním toku Berounky, Úhlavy, Radbuzy, z Ohře na dolním toku pod Terezínem nebo v Sázavě. Výskyt byl potvrzen i na několika místech ve Vltavě v Praze a níže po proudu. Největším překvapením však byl nález početné populace ve Vltavě v Praze v r. 2007 a 2009 při snížení hladiny, které provedlo Povodí Vltavy. Odhadovaný počet jedinců škebličky ve Vltavě v Praze činil 150 000 (Douda a kol. v tisku)., The Depressed River Mussel (Pseudanodonta complanata) has always been considered in the Czech Republic to be a rare inhabitant of larger rivers. First data on its occurrence were provided more than 140 years ago. The species is known from the Dyje and lower Morava (Danube drainage basin), Odra River (Odra drainage basin) and more data exist from the Elbe drainage basin from the rivers Elbe, Vltava, Ohře, Berounka, Úhlava, Radbuza, Lužnice, Nežárka, Otava and Orlice. The largest population with an estimated number of about 150,000 individuals has been found in the Vltava in Prague., and Luboš Beran.
The main purpose of the research was to determine the conditions affecting ice phenomena, including the three-phase cycle of ice: expansion, retention and decay of the ice cover on selected rivers of the Baltic coastal zone in the Northern Poland (Przymorze region). The analysis has been elaborated for the years 1951–2010 against the backdrop of currently occurring climatic changes, with particular emphasis on the development and phase variability of the NAO. The article presents the impact of the variability in atmospheric circulation which has manifested in an increase in air temperature, over the last 20 years, on thermal conditions during winter periods in the South Baltic Coastal Strip. The increase in air temperature has contributed to an increase in the temperature of river waters, thus leading to a shortening of the duration of ice phenomena on rivers in the Przymorze region. The article also brings to light an increased occurrence of winter seasons classified as cool, and a disruption in the occurrence of periods classified as normal over the last 30 observed years. The research has demonstrated a significant dependence between the seasonal change in air temperature and the variability of thermal conditions of water, which has a direct impact on the variability of the icing cycle of rivers in the Przymorze region. The authors also show that the variability in forms of ice phenomena for individual river sections is determined by the local factors, i.e. anthropogenic activity, impact of urbanized areas or inflow of pollutants.