Volume 46 (2017): Issue 2 (June 2017)

This study examined the stomach contents of 230 individuals out of 439 samples obtained from commercial fishermen between January 2013 and March 2014 from a trawler using trawl bags with a full cod-end mesh size of 44 mm.

It was found that 216 samples were full and the stomach fullness index was estimated at 93.9%. The varying diet composition of the species was determined by estimating the percentage numerical composition (N%), frequency of occurrence (F%), gravimetric composition (W%) and the index of relative importance (IRI%). Diversity (Shannon index), richness (Margalef index) and similarity (Bray-Curtis index) of the catches in different seasons were calculated using the Biodiversity Professional (Version 2) software.

Three major groups were identified in the catches: Crustacea, Mollusca and Teleostei. At least 17 different prey groups were identified. With regard to the diversity of consumed prey, the winter (1.204), autumn (1.079) and spring (1.000) seasons were characterized by a medium level of diversity, summer (0.699) – by a low level of diversity. However, the richness of prey does not show seasonal differences. As indicated by the Bray-Curtis index, the highest similarity between the prey groups was observed between the autumn and winter seasons, at 81.61%.

We identified 209 species of algae and cyanobacteria at 4 sites in the Kabul River. Green algae, diatoms, and charophytes dominated in the river, which reflects regional features of agricultural activity. Species richness and algal abundance increased down the river. The Water Quality Index characterizes the quality of water down the river as medium to bad. The index of saprobity S reflects Class III water quality. The Water Ecosystem Sustainability Index (WESI) shows contamination with nutrients. According to the River Pollution Index (RPI), waters in the river have low alkalinity and low salinity, and are contaminated with nutrients. Pearson coefficients showed that water temperature plays a major role in the total species richness distribution (0.93*) and in the green algae distribution (0.89*), while cyanobacteria were stimulated also by water salinity (0.91*). Stepwise regression analysis indicated water temperature as the major regional factor that determines riverine algal diversity. Surface plots and Canonical Correspondence Analysis (CCA) showed that salinity, nitrates, temperature, and Biochemical Oxygen Demand (BOD) can be defined as major factors affecting algal diversity. Dendrites mark the upper site of the Warsak Dam as the source of the community species diversity. Bioindication methods can give relevant and stable results of water quality and self-purification assessment that can be employed to monitor the regional water quality.

Lake Mariut is suffering from pollution as it receives industrial effluents and a mix of sewage from different drains, often lacking treatment systems. Sequential extraction procedures were applied for the speciation of heavy metals (Fe, Mn, Zn, Cu and Pb) and P in the lake sediment to evaluate their potential bioavailability. Total concentrations of metals had low values compared with the sediment quality guidelines. The chemical speciation data for Mn and Zn indicate a potential pollution level since the non-residual fractions contain up to 77.6 and 64.9% (respectively) of the total metal content. However, Fe, Cu and Pb are mostly linked to the inert fraction. Risk assessment of metals was carried out using the mobility factor, the contamination factor, the risk assessment code and the enrichment factor. All the analytical approaches indicated the accumulation of pollutants exceeding the adsorptive capacity of Lake Mariut sediments. The organic phosphorus fractions dominated in the sediment accounting for 51.4%, while the most abundant form of inorganic phosphorus was Ca-bound phosphorus. The rank order of P fractions was HCl-P > NaOH-P > BD-P > NH₄Cl-P > Res-P. The decrease both in the dissolved oxygen level in the lake water and the Fe:P ratio in the lake sediment resulted in the high contribution of the phosphorus fractions to the overlying water.

The occurrence of nematodes in the alimentary tract of great cormorant Phalacrocorax carbo (L., 1758) nestlings was studied in the Włocławek Reservoir located on the Vistula in central Poland and in adult birds wintering in the south of Poland, with the food base in the upper Vistula. Mixed (max 4 species) nematode infections were found in all birds. Apart from Contracaecum rudolphii Hartwich, 1964 found in all studied birds, the third- and fourth-stage larvae as well as adult individuals of the following species were also present: Eustrongylides excisus Jägerskiöld, 1909, Anisakis simplex (Rudolphi, 1809), Hysterothylacium aduncum (Rudolphi, 1802), Desmidocercella numidica Seurat, 1920, Synquaria squamata (Linstow, 1883), Cosmocephalus obvelatus (Creplin, 1825), Baruscapillaria carbonis (Dubinin et Dubinina, 1940). The overall mean intensity of infection with nematodes was 23.4 ± 11.6 in nestlings and 175.7 ± 110.9 in adult cormorants. The most common species was C. rudolphii with the mean infection intensity of 12.5 ± 5.9 in nestlings and 154.6 ± 111.4 in adults. The second most common species was E. excisus. S. squamata, C. obvelatus and D. numidica were less common in both age groups. A. simplex and H. aduncum were found only in nestlings, while B. carbonis only in adults.

The study determines the differences in Pb accumulation in sediments of dam reservoirs with respect to locations of the old river beds and their depth (deep Czorsztyn Reservoir and shallow Goczałkowice Reservoir in southern Poland). Parameters (grain size, organic matter content and reservoir depth) that may influence the spatial distribution of Pb concentrations in the sediments were analyzed. Based on the hierarchical cluster analysis, sediment samples from the reservoirs were ranked with respect to particle size distribution. We found differences in the spatial distribution of grain size and organic matter in the studied reservoirs, caused mostly by the topography of these reservoirs. The spatial distribution of Pb concentrations in the sediments of the Czorsztyn Reservoir (range 4.8-35.8 μg g^-1) and the Goczałkowice Reservoir (range 11.3-59.4 μg g^-1), regardless of their average depth and their type (dimictic, polymictic), depends on the distribution of silty clay and clay fractions, organic matter and reservoir depth. Therefore, Pb spatial distribution was more regular in the Czorsztyn Reservoir than in the Goczałkowice Reservoir. Locations of the old river beds had a significant impact on the Pb distribution in the sediments of both reservoirs.

The results of the recent (2014-2015) inventory and three historical datasets (1949-1959, 1960-1980 and 1997-2007) were analyzed in order to track the long-term changes of charophytes in the largest estuarine lagoon of the Baltic Sea. The present species composition of charophytes in the estuarine part of the Curonian Lagoon consisted of 7 species, including tolerant to salinity (Chara aspera, C. contraria, C. globularis and Nitellopsis obtusa) and typical brackish-water species (Chara baltica, C. canescens and Tolypella nidifica). The highest congruence of species was between the 1997-2007 and 2014-2015 datasets, which covered respectively eutrophication and post-eutrophication periods. The 1949-1959 dataset (closest to the reference conditions) differed by the absence of typical brackish-water species. The 1960-1980 dataset (the major period of eutrophication) was relatively poor in study sites and species. During the last 6 decades, only tolerant to salinity freshwater species were constant and abundant; only Nitella mucronata can be considered as extinct. Recently, C. contraria became dominant and widespread. The changes in the charophyte species composition, abundance and distribution can be explained by different intensity of surveys and/or density of study sites, but also by the increased exposure to brackish waters since 1980s and/or recently reduced effect of eutrophication.

Because of the slow current velocity, man-made ditches may create distinct physical and ecological conditions that are suitable for the growth of zooplankton populations. However, the influence of drainage ditches on zooplankton communities has not been studied yet. This study aims to answer the following questions: i) Are man-made ditches a rich source of zooplankton? ii) What current velocity value leads to abundant zooplankton in man-made ditches? iii) Do zooplankton communities differ between man-made ditches and connected natural streams? In man-made drainage ditches with a water current lower than 0.1 m s^-1, the abundance of zooplankton was greater than in the majority of streams. Sometimes this level of abundance was equivalent to the densities of zooplankton in lakes or dammed reservoirs. The presence of zooplankton in man-made ditches may be of great importance to the establishment of food webs, particularly during periods of high water levels or heavy rainfall, both of which may accelerate the water current, causing the dispersion of zooplankton along the ditches and into natural streams.

Planktonic ciliate composition, abundance and its response to environmental change were investigated during four seasons (winter of 2013, spring, summer and autumn of 2014) in Daya Bay, the South China Sea. A total of 41 species belonging to eight orders were identified, 14 of which were dominant. Planktonic ciliate communities showed a distinct seasonal pattern in ciliate abundance and a clear seasonal shift in the taxonomic composition. The largest number of ciliate species occurred in summer, whereas the highest abundance peaked in spring, mainly due to oligotrichids. In terms of spatial distribution, ciliate species were abundant in the area of artificial reefs, and ciliate abundance was higher in the Dapeng Cove aquaculture area and lower at the Daya Bay Nuclear Power Station. Clustering analysis demonstrated that the seasonal variations of the ciliate community structure were more obvious than spatial variations. Multivariate and univariate analyses illustrated that ciliate abundance was significantly correlated with the water nutrient level and chlorophyll-a concentration, temperature, salinity and dissolved oxygen. Moreover, the dominant abiotic environmental factors affecting the spatial pattern of ciliate communities varied between seasons.

Due to the limited water exchange, lagoons are particularly prone to eutrophication. The consumption of oxygen in this process, coupled with simultaneous enrichment of bottom sediments with organic matter, reinforces the occurrence of anaerobic conditions and methanogenic growth. Methanogenic archaea activities cause depolymerization of organic compounds accumulated in sediments. As a result of such ecosystem transformation, methane might be produced and emitted from this basin. Chemical studies conducted in 2010 were focused on methane content in the surface bottom sediments in the Polish part of the Vistula Lagoon. The results showed that the highest methane concentration occurs in the southwestern part of this basin (6.45 mmol dm^-3), while the lowest one in the southeastern part (7.1 × 10^-3 mmol dm^-3). Molecular studies were focused on specific methanogenic archaea gene identification. The comparison of nucleotide sequences of “mcrA gene” clones obtained from genomic DNA isolated from the Vistula Lagoon sediments indicates a similarity to the yet uncultivated archaea, but also to archaea from the Methanosarcinales and Methanomicrobiales orders.

Mytilopsis leucophaeata (Conrad, 1831) is native to the western Atlantic coast of North America. It has been reported in many regions outside its home range, including the Gulf of Gdańsk (the southern Baltic Sea). Although the conditions in the area seem to be favorable for the species, there have been no reports about its presence elsewhere in the gulf. However, the data probably did not reflect its actual distribution in the region, as the species can be easily misidentified for other bivalves living in the area, and it prefers hard substrates, which have not been studied as extensively as soft substrates. Our study was aimed at determining the actual distribution of M. leucophaeata in the Gulf of Gdańsk, the Vistula Delta and the Vistula Lagoon. The results showed that the species was not widely distributed in the Gulf of Gdańsk and was absent in the Vistula Lagoon. The only new records come from the Vistula Delta where the abundance of M. leucophaeata was up to 69 ind. m^-2, i.e. significantly higher than in the Gulf of Gdańsk. Individuals found in the Vistula Delta were also significantly larger, with the length of shells reaching 22-23 mm, which is considered to be the maximum for the species.

This paper presents first polish site of Luticola frequentissima Levkov, Metzeltin & Pavlov, with morphological and ecological characteristics. The species was found in samples collected from flowing waters and soils within the area of the Bieszczady National Park and the Magura National Park. In south-eastern Poland a low number of Luticola frequentissima cells occurred in small shaded streams. It was most frequently observed in aerophitic places (shallow and drying watercourses) and in soils. In the studied samples, apart from those cells with typical dimensions, much smaller and narrower cells with a higher number of striae were found in comparison to those in the currently available literature.

The Asiatic bivalve Sinanodonta woodiana (Lea, 1834), which is more and more widespread in all parts of Europe, in Poland has been mostly reported from lentic waters, especially fish ponds. In contrast to some other European countries, no data have been published on its presence in rivers of Poland. In 2015, monitoring was carried out in the lower Oder River and in the mouth of the Warta River, as a result of which S. woodiana was recorded there for the first time. This was possible due to prolonged drought, which led to extremely low water levels in most of the inland water bodies and watercourses, so that other research methods could be used. The presented results confirm that the species spreads easily by colonizing waters of various types, which in the future may lead to the formation of large populations.

The benthopelagic oilfish Ruvettus pretiosus Cocco, 1833 was recorded for the first time from the Marmara Sea coast in Turkey. In addition, this is the third record of the species from the Turkish sea waters.