Volume 45 (2016): Issue 3 (September 2016)

Dispersal of crustacean zooplankton from a reservoir in a lowland river was observed over a relatively long distance. Zooplankton samples were collected by a unique technique from “the same water”. Large Cladocera (Daphnia cucullata and Diaphanosoma brachyurum) showed the greatest reduction in a river, but they were common over a distance of up to 130 km below a dam. These two planktonic species revealed a low potential for colonizing oxbow lakes. Eurytopic Chydorus sphaericus and Mesocyclops leuckarti transferred from the Siemianówka Reservoir had a great dispersal capacity in the Narew River and could effectively support local populations in oxbow lakes over a distance of 180 km.

Similarity between the crustacean communities in the river and the reservoir significantly decreased with the increasing distance from the dam. At the same time, crustacean communities in oxbow lakes were not affected by the distance from the source. Dispersal from the large source of zooplankton to local communities is a very important process but the local environmental factors such as habitat heterogeneity, aquatic vegetation and the hydrological connectivity can be strong enough to affect the structure of local crustacean communities in oxbow lakes.

Epilithic diatoms from the Vrla River (Serbia) have been used to assess the ecological status of water. A total of 227 diatom taxa belonging to 50 genera were identified in the Vrla River during six research seasons with 13 dominant species recorded. Gomphonema (30 species), Navicula (28) and Nitzschia (26) were the most species-rich genera, followed by Pinnularia (12) and Encyonema (11). One taxa was recorded as new to Serbia – Geissleria acceptata. CCA grouped the diatom taxa into three main groups. The first group included taxa found at most of the sampling sites, the second group involved diatom taxa significantly positively correlated with the oxygen, while the third group showed positive correlation with temperature. RDA showed that some diatom taxa, including: Cocconeis placentula var. placentula, C. placentula var. lineata, C. pseudolineata and Mayamaea atomus var. permitis, are significantly positively correlated with temperature, while others, for example Achnanthidium minutissimum, Hannaea arcus, Nitzschia pura are mostly correlated with total phosphorus, alkalinity and water hardness. The ecological status of the Vrla River ranged from moderate, good to high. It was shown that according to the diatom indices, the ecological status of water downstream and upstream of a trout fish pond was slightly different.

A rare chironomid species, Cladotanytarsus molestus Hirvenoja, 1962, collected at Lake Straszyńskie (the drinking water reservoir for the city of Gdańsk), was recorded from Poland for the first time. The adult male of the species is redescribed, and intraspecific morphological variations of diagnostic structures are presented in detail. Data on the species’ biology are also provided.

The paper presents the forms of grounded grease ice ridges as well as hydrological, meteorological and physiographic conditions of their occurrence on the south coast of the Baltic Sea. The author used results of observations and measurements performed during hiking expeditions and analyzed profiles and photographs showing the morphology of grease ice ridges which occur along the coast and are usually several meters wide and 1-3 m high. Their windward slopes are very steep, usually concave, with abrasion niches and ice cornices formed by waves. The leeward slopes are gentle (20-30°) and coincident with the angle of the natural slip (angle of slide) of the grease ice, slush and shuga tossed by waves. The major factor leading to grease piling is the movement of waves generated by a strong onshore (NW, N, NE) wind. Such wind conditions occur mainly when a low-pressure area extends to the E, SE and/or S of the southern Baltic, and a high-pressure area – to the W, NW and/or N.

Despite large karyotype differences between parental species, the hybrid progeny of the sea trout (Salmo trutta) females (2n = 80, FN = 100) and the Atlantic salmon (Salmo salar) males (2n = 58, FN = 74) may be viable and even fertile. As hybrids would pose threat to natural populations of parental species through backcrossing, gonadal development in the sea trout × Atlantic salmon hybrids has been studied in the present work. Moreover, cytogenetic investigation was performed to identify any changes in the number and structure of chromosomes that may affect gonadal differentiation and gamete production in the hybrid progeny. Eight males, two intersex individuals and one female were described among the two-year-old hybrids. Some of the hybrid males were already spermiating during the study. Predominance of the testicular component in the gonads was observed in both intersex individuals. Prevalence of males and the presence of intersex individuals together with only one female may suggest disturbances in the gonadal development only in females. Homogeneity of the chromosome number (69) and the chromosome arm number (87) in the hybrid individuals analyzed in this study suggests that unpaired chromosomes disturbed the development of ovaries but not testes.

Despite its ecological importance, little information is available regarding spatial and seasonal changes in the testate amoebae community in peat bogs. The objectives of this study were to examine the structure of communities and horizontal distribution of testate amoebae fauna, to improve the understanding of factors affecting the distribution of moss testate amoebae communities and to analyze the seasonal changes in testate amoebae communities in a Sphagnum-dominated peat bog (eastern Poland). A total of 45 testate amoebae species were identified in the samples. The highest species richness occurred in hollows dominated by Sphagnum angustifollum, much lower numbers of taxa were observed in hummocks dominated by Sphagnum magellanicum and Polytrichum. The Monte Carlo permutation test showed the significance of N_tot, temperature, pH, and the depth to the water table for the variability of testate amoebae in all microhabitats. Species found in spring samples were associated with the increased N_tot content. Species occurring in summer samples were associated with the increasing pH gradient and species developing in late spring and autumn preferred a greater depth to the water table.

The current study was conducted to estimate the baseline concentration of heavy metals in the surface sediment of Marudu Bay. Environmental parameters were measured at the seafloor and samples of the surface sediment were collected at monthly intervals for the period of 12 months. The organic content, total N, total P and concentration of 16 trace metals in the surface sediment were analyzed. The baseline concentration of metals was estimated by geochemical normalization. Anthropogenic inputs of metals were then estimated by calculating the enrichment factor for each element. The result demonstrated that the C/N ratio of sediment at Marudu Bay varies from 15 to 342, which indicates the dominance of terrestrial organic matter. The baseline concentration of V, Fe, Mn, Zn, Ti, Rb and Sr were 26.74 mg kg^-1, 1.04%, 205.31 mg kg^-1, 34.09 mg kg^-1, 507.61 mg kg^-1, 93.25 mg kg^-1, 37.56 mg kg^-1, respectively. The concentration of most metals was comparable to the baseline, except Mn and Zn which showed higher concentrations in most parts of Marudu Bay. In conclusion, the metal concentration in Marudu Bay is still within the permissible levels and should not cause any threats to public health.

Pentachlorophenol (PCP) is an anthropogenic substance, toxic to humans. The major source of this compound in the environment are wastes from factories producing PCP and materials (textiles, wood) treated with PCP. In 2008, a dossier was prepared to support the inclusion of PCP in Annex I to the Protocol of the 1979 Convention on Long-Range Transboundary Air Pollution on Persistent Organic Pollutants. The draft decision to add PCP along with its salts (NaPCP) and esters (PCPL) in Annex A of the Stockholm Convention was adopted during the seventh meeting of the Conference of the Parties to the Stockholm Convention in 2015. The aim of present study was to assess the status of contamination in Puck Bay with this harmful substance. The surface bottom sediments of Puck Bay were contaminated with pentachlorophenol to varying degrees, ranging from 17.4 ± 5.6 ng g^-1 d.w. to 230.1 ± 20.8 ng g^-1 d.w. The majority of samples collected from deepwater areas of Puck Bay were contaminated with PCP above 25 ng g^-1 d.w. (value of Predicted No Effect Concentration). It has been assessed that bottom currents occurring in Puck Bay can affect sediments deposited at the Gdynia dumping site.

Two charophyte species (Chara tomentosa Thulli. 1799 and Chara globularis L. 1753) were studied to assess their biomass and CaCO₃ production in seven hard-water lakes in Western Poland. In each lake, samples of ten individuals from three study sites were collected for dry weight (DW) and calcium carbonate content (% CaCO₃) analyses. Additionally, physicochemical parameters of water collected from the above sampling sites were analyzed.

No significant differences were found between the study sites in each lake for any of the analyzed parameters. In all the lakes, DW of C. tomentosa (0.60 ± 0.23 g indiv.^-1) was significantly higher and more differentiated than DW of C. globularis (0.11 ± 0.08 g indiv.^-1), suggesting species-specificity. The CaCO₃ content in DW for C. tomentosa was higher (58.8-70.9%) than in C. globularis (50.1-68.3%), however, it did not reflect the DW differentiation, suggesting lake-specificity. The physicochemical properties of water revealed clear lake-to-lake differentiation. Different correlations between dry weight and calcium carbonate content and lake characteristics were found for each species. The results showed that DW and % CaCO₃ are closely related to habitat conditions and different factors may influence the individual biomass of each species.

In aquatic environments, ciliates integrate the energy flowing through bacteria, smaller protozoa, and the prevailing fraction of algae and are further grazed upon by metazooplankton. Ciliates are incorporated into budgets and models describing ecosystem functioning. However, data for the parameterization and validation of models remain insufficient. In this study, annual production to biomass (P/B) ratios of pelagic ciliates were estimated in four lakes of different trophic status and at two sites located in the coastal zone of the Baltic Sea. All study sites were located in the temperate zone. The calculations were based on bulk data reflecting seasonal changes in ciliate production, which was estimated using an allometric equation. The annual ciliate P/B ratio for surface waters was 308 ± 81 yr^-1 (mean ± standard deviation). There was no statistically significant relationship between the mean annual ciliate biomass in particular water bodies and the annual P/B ratio. In the near-bottom waters, the annual P/B ratio was 78 ± 39 yr^-1. Because of the possible food limitation of ciliate growth and reconstructions of the community due to changes in environmental conditions, the ciliate P/B ratio applied in models of temperate waters should range from 50% to 100% of the P/B ratios estimated in this study.

The article examines the spatial and temporal variability in selected extreme meteorological phenomena on the Polish coast of the Baltic Sea. Data from the 2001-2014 period related to a few meteorological and oceanographic elements were used to calculate indices of extreme weather events. The amount of intensive and widespread precipitation events in the 21^st century corresponds well with the long-term means and is stable over a long period. The number of 50-60 frost days recorded per year has been systematically decreasing for several decades. Only a few deep cyclones occur per year and year-to-year variations of their number and magnitude corresponds to the overall long-term insignificant changes in the cyclone activity in the North Atlantic and the European region. The mean annual number of days with strong winds reaches nearly 8 cases per year. About 6 storm surges per year are recorded and this value has been slowly increasing in the long-term perspective. The rare occurrence of sea ice in 2001-2014 is a continuation of the reduction in the phenomenon observed in the 20^th century. The passage of deep cyclones resulting in strong winds, storm surges and waves constitutes the most dangerous hazard to the coast.

The paper is based on the hypothesis that coastal lakes significantly affect changes in the quality of freshwater coming from catchments, which is best reflected in the reduction of biogenic loads. Some of the main reasons for this phenomenon include unique geographic locations of coastal lakes and physical and chemical properties of their waters as well as other hydrographic determinants that affect water circulation in catchments. The study area covered the direct drainage basin of Lake Lebsko, which is located in Słowiński National Park in northern Poland, on the coast of the southern Baltic Sea. The study was conducted from June 2008 to October 2010. Fieldwork was the main part of the research project and included hydrographic mapping, water sampling for laboratory analysis, and measurement of the discharge in all tributaries and outflows of the studied lake. Water chemistry data for Lake Lebsko indicate a significant accumulation of biogenic materials in the lake, which proves a strong effect exerted by the lake on the incoming water. This is true for both total chemical loads per year as well as concentrations of selected ions over short time intervals. This standard pattern may be interrupted by seawater intrusions that alter water chemistry in the whole lake.