Oceanological and Hydrobiological Studies

Species diversity of gastrotrich communities on elodeids and in bottom sediments of lakes of different trophic status was compared. Thirty-eight species of Gastrotricha (34 in bottom sediment and 21 on elodeids) were found, which belong to the only family of Chaetonotidae Zelinka, 1889. Species diversity of both habitats was reflected in the diversity indices ranging from 2.02 (a dystrophic lake) to 2.67 (a strongly eutrophic lake) for bottom sediment, and from 2.01 (a mesotrophic lake) to 2.54 (a strongly eutrophic lake) for elodeids. The similarity of gastrotrich fauna from the two habitats was low, and varied from 17% (a mesotrophic lake) to 38% (a strongly eutrophic lake). Low similarity of elodeid fauna from lakes of different trophic status was also found, in spite of similar plant species composition. The lowest similarity in elodeid fauna (23%) was recorded for dystrophic and mesotrophic lakes, whereas the highest one (68%) was observed for eutrophic and strongly eutrophic lakes. That allows to conclude that the diversity of epiphytic fauna is affected by trophic status rather than by vegetation type. The comparison of the gastrotrich fauna from elodeids and bottom sediments in lakes of different trophic status provides additional autoecological characteristics of Heterolepidoderma ocellatum (Mečnikow, 1865) and allows to recognize this species as belonging to a group of species closely related to macrophytes.

Specimens of Piscicola pojmanskae were identified in the macrozoobenthos community in Zostera meadows in Puck Bay. The presented paper is the first report on the observation of this species in the Gulf of Gdańsk (the southern Baltic Sea). Leeches are a rare component of the benthic fauna in this brackish water area.

The discovery of a shell of the Chinese pond mussel in 1998 and further confirmation of this species indicate that a reservoir with natural thermal conditions is the oldest species location in Poland. Growth increments of an archival shell do not fall within the ranges obtained by this species in Konin lakes. They are, however, close to population ranges from Hungary. In contrast to other specimens found, the analyzed shell has a very high H/L ratio and is thicker. The observed features might result from the founder effect or they might point to a considerable plasticity of the species.

The main objective of this paper is to report two benthic, epilithic diatom species from the Raška River. Samples were collected in April, June, August and November 2011 and March and May 2012 from 5 localities along the Raška River by scraping off the stone surface using a brush. Diatom frustules were first cleaned using the cold acid method, and then mounted on permanent slides. Descriptions (main valve measurements of the populations in the Raška River), ecology, distribution in Serbia and Europe, and appropriate photomicrographs of two species are presented. Navicula jakovljevicii Hustedt and Navicula catalanogermanica Lange-Bertalot & Hofmann are rarely found in Europe and these are new distributional records. These new taxa significantly contribute to diatom floristic diversity of the Raška River.

Species composition of plankton ciliates was studied in the Curonian Lagoon in 2007–2008 and compared to long term investigations dating back to the 1980th. In total, 152 taxa were identified at the level of species or genera. More species (76 species/higher taxa) was found in the estuarine part of the Lagoon due to temporally unstable salinity and the presence of both freshwater and brackish/marine species. Some of the brackish/marine species: Tintinnopsis baltica, Tintinnopsis kofoidi, Cothurnia maritima, Lohmaniella oviformis, Lohmaniella spiralis and Helicostomella subulatum were recorded for the first time in the lagoon. The ciliate community at the freshwater sites was less diverse, containing 63 species/higher taxa in the central stagnant part of the Lagoon and 47 — in the Nemunas River avandelta. The comparison of present and past studies revealed that the use of a single live-counting method could lead to underestimation of small nanociliate species, whereas examination of Lugol fixed material provides relatively poor taxonomic information.

Species abundance and richness of rotifer communities occupying monospecies beds of Vallisneria was studied in Lake Licheńskie included in the open cooling system of heat and power stations. Differences were found in rotifer numbers, species composition and diversity between sampling points within the same location and between the locations. Factors that seem to be responsible for the high diversity of rotifer communities inhabiting Vallisneria beds are: large-scale horizontal diversity (between macrophyte patches), small-scale horizontal diversity (within patches) and the high vulnerability of Vallisneria epiphyton to disturbances caused by wave action.

Peat bogs are unique and important habitats for biodiversity at the species and ecosystem level where low pH of water plays a major role. The main objective of the present study was to compare the benthic diatom assemblage structure of the selected part of the Fenn’s and Whixall Mosses complex in order to verify whether selected sampling sites differ from each other. The complex is a cut-over, lowland raised mire, which is a National Nature Reserve (NNR) and a Site of Special Scientific Interest (SSSI).

Altogether 92 diatom species were identified in 72 benthic samples collected between September 2008 and August 2009 from six selected sampling sites. Statistical cluster analysis was used to classify diatom samples and to observe the structure of diatom assemblages. The results of this analysis grouped the data set into 3 clusters with 24 samples from each of the two sampling sites in one cluster. Such a clear division shows that pH of water has an impact on the species composition, the richness and diversity of benthic diatom assemblages.

An oceanic model and satellite data are used to evaluate the seasonal distribution of chlorophyll-a (Chl-a) in the Bay of Bengal (BoB) and Andaman Sea. Satellite data show high Chl-a concentrations because high Chl-a concentrations reduce CO2 and increase O2 at the sea surface, indicating fish abundance in the ocean. Sample collection alone cannot provide an accurate overview of Chl-a concentration over an entire region. The satellite data concerning Chl-a concentration, phytoplankton absorption coefficient, and Sea Surface Temperature (SST) are from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) project and from the Moderate Resolution Imaging Spectroradiometer (MODIS). The oceanic model is created to give the surface circulation as a result. The research finds that the simulation is in agreement with SST, Chl-a concentration, and phytoplankton absorption coefficients obtained from satellites. The conclusion is that the oceanic model can be used to implicitly explain the seasonal distribution of Chl-a in the Bay of Bengal and Andaman sea.

The European anchovy, Engraulis encrasicolus (Linnaeus, 1758), enters the Baltic Sea only occasionally. Little is known about the parasites that inhabit this fish in the northern part of its natural range (north-eastern Atlantic). This study is based on 32 anchovies sampled in autumn 2006 from a substantial bycatch accompanying sprat in the Gulf of Gdańsk (southern Baltic Sea). The fish were examined using standard parasitological procedures, and yielded 10 L3 larvae of the nematode Hysterothylacium aduncum (Rudolphi, 1802). The prevalence and the intensity (mean and range) were 21.9%, 1.4, and 1–4, respectively.

Bài báo đánh giá tình trạng sinh thái của hồ Gorbacz cạn (Đông Bắc Ba Lan) trong giai đoạn cuối trước khi cạn kiệt hoàn toàn. Trong vài năm qua, chế độ thủy văn của lưu vực hồ đã thay đổi đáng kể do hoạt động của mỏ than bùn gần đó và các đợt hạn hán kéo dài vào mùa thu trong những năm tiếp theo. Sự phát triển của các loài thực vật nổi đã dẫn đến sự bao phủ hoàn toàn của các loài thực vật nổi kể từ năm 2000. Các phân tích bao gồm hồ sơ từ các mẫu trước đó và dữ liệu về hình thái học, chất lượng nước, thực vật phù du, động vật phù du và thực vật nổi. Trạng thái dinh dưỡng của hồ Gorbacz đã được xác minh so với các nghiên cứu trước đây. Kết quả cho thấy ngay cả với lượng nước tối thiểu, hồ Gorbacz vẫn giữ được tính chất dystrophic của nó với sự gia tăng màu nước và nồng độ DOC, chất dinh dưỡng sinh học, chlorophyll a. Chỉ số tình trạng humic (HSI) và chỉ số dystrophy hóa học thủy (HDI) xác nhận tình trạng dystrophic của hồ với các giá trị lần lượt là 71.3 và 76.2. Cả hai đại diện thực vật phù du điển hình của nước eutrophic và dystrophic đều được ghi nhận. Độ đa dạng rất cao của desmids trong telmatoplankton cho thấy quá trình cạn kiệt đang diễn ra trong hồ. Động vật giáp xác planktonic được đại diện bởi các loài lọc nhỏ. Cộng đồng Rotifera bị chiếm ưu thế mạnh mẽ bởi Trichocerca simonei. Bài báo kết luận với các nguyên nhân chính của những thay đổi đã quan sát và một số nhận xét cho tương lai về tình trạng hồ.