Impact of the Słupia River waters on microbial communities in the port of Ustka and adjacent Baltic Sea waters

The distribution of bacterial and ciliate abundance, ciliate community composition and other parameters were studied during summer along a transect from the mouth of the Słupia River to offshore waters (southern Baltic Sea). Bacteria were examined under an epifluorescence microscope and ciliates were observed under an inverted microscope. Two water masses were identified along the transect. Less saline waters in the river mouth and in the surface layer in the port of Ustka were characterized by high bacterial abundance (5.51–6.16 × 106 ml−1) and low ciliate abundance (0.34–0.90 cells ml−1). More saline waters in the near-bottom zone in the port of Ustka and in the surface layer outside the port contained smaller numbers of bacteria (0.99–2.14 × 106 ml−1) and larger numbers of ciliates (2.65–5.40 cells ml−1). The differences were statistically significant. The separation of the two water masses indicated that the Słupia River exerted a minor impact on the marine waters. The ciliate community composition changed along the transect studied. The main statistically significant difference observed was the low contribution of oligotrichs and choreotrichs to ciliate biomass (3–4%) in less saline waters and their dominance (45–80% of ciliate biomass) in more saline waters.

Spatial and seasonal variations in the planktonic ciliate community and its relationship with environmental factors in Daya Bay, the South China Sea

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-

The trophic role and impact of plankton ciliates in the microbial web structure of a tropical polymictic lake dominated by filamentous cyanobacteria

The recent interest in the plankton structures and dynamics in tropical and subtropical lakes has revealed important trends that set these lakes apart from temperate lakes, and one of the main differences is the enhanced importance of the microbial food web with respect to net plankton. Ciliates are a key component of subtropical and tropical microbial webs because of their role as dominant picoplankton grazers and their ability to channel picoplankton production to the uppermost trophic levels. Plankton ciliates have been found to play a crucial role in the survival of fish larvae in lakes that share several features with Lake Catemaco, a eutrophic tropical Mexican lake. Therefore, the plankton ciliate composition, abundance, and biomass of Lake Catemaco were studied to assess their role in the microbial food web. The data were obtained from surface and bottom water samples collected at eleven points during three surveys in 2011 and an additional survey in 2013, with the surveys covering the local climatic seasons. The most abundant components of the plankton ciliate assemblages were small prostomatids (<em>Urotricha </em>spp.), choreotrichs (<em>Rimostrombidium </em>spp.), cyclotrichs (<em>Mesodinium </em>and<em> Askenasia</em>), and scuticociliates (<em>Cyclidium, Cinetochilum, Pleuronema, </em>and <em>Uronema</em>). Other important ciliates in terms of abundance and/or biomass were haptorids (<em>Actinobolina, Belonophrya, Monodinium, Paradileptus, </em>and <em>Laginophrya</em>), <em>Halteria</em>, oligotrichs (<em>Limnostrombidium</em> and<em> Pelagostrombidium</em>), <em>Linostomella, Bursaridium, Cyrtolophosis,</em> and<em> Litonotus</em>. The ciliate abundance averaged 57 cells mL^-1 and ranged from 14 to 113 cells mL^-1. The mean ciliate biomass was 71 µg C L^-1 and ranged from 10 to 202 µg C L^-1. Differences were not detected in ciliate abundance or biomass between the sampling points or sampling depths (surface to bottom); however, significant differences were observed between seasons for both variables. Nano-sized filamentous cyanobacteria were the most abundant component of the plankton, and their abundance was assessed through epifluorescence microscopy counts. The autotrophic and heterotrophic picoplankton abundance was measured through epifluorescence, and their abundance and biomass were higher at the study site relative to other shallow freshwater ecosystems. The total ciliate biomass distribution patterns were similar to those of filamentous cyanobacteria and autotrophic or heterotrophic picoplankton, although the nanociliate biomasses peaked when the picoplankton and filamentous cyanobacteria were least abundant. The consequences of this increased importance of ciliates on the structure of the plankton at Lake Catemaco will be discussed along with the probable causes.

Microphytoplankton and ciliate communities’ structure and distribution in a stressed area of the south coast of Sfax, Tunisia (eastern Mediterranean Sea)

The environmental parameters, microphytoplankton and ciliate communities in the area were studied in spring and autumn at 20 stations along the coast south of Sfax over two seasons during 2011. The results showed that the environmental parameters indicated high nutrient levels and their concentrations ranges reported as criteria of eutrophication in coastal waters. A total of 78 microphytoplankton species were identified, belonging to Diatoms, Dinoflagellates, Cyanobacteriae, Euglenophyceae, Dictyochophyceae and Chlorophyceae. The numerical density of phytoplankton was high over the whole area, with season averages between 44.10×102 ±41.93×102 and 103.55×102 ± 107.33×102 cells L–1. A total of 58 ciliate species were identified at all of the stations. Tintinnids abundance was generally higher than naked ciliate abundance reported for autumn and spring seasons, both at the surface layer and water–sediment interface. One striking point was that ciliate abundance was unchanged in autumn (4×102 cells L–1) but was still higher in spring (6×102 cells L–1). Some species reported in this study are commonly found in the stressed coastal waters.

Latitudinal pattern of abundance and composition of ciliate communities in the surface waters of the Atlantic Ocean

Abundance, biomass, and taxonomic composition of the ciliate community were studied in the surface waters along a transect between 50°S 61°W and 48°N 5°W (Atlantic Ocean, March-April 2011). The abundance of heterotrophic ciliates was low in the equatorial zone (280–320 cells l−1, 0.11–0.12 μg C l−1), but it increased toward both the northern and southern temperate zones with the maximum abundance observed at 44°S (2667 cells l−1, 0.82 μg C l−1). This pattern resembles the global distribution of oceanic primary production, which is low at lower latitudes and high in temperate zones. In temperate zones ciliate abundance peaks during spring and fall. Thus, because the present study was carried out during spring in the northern hemisphere and austral fall in the southern hemisphere, the ciliate abundance at higher latitudes was additionally elevated. Functionally autotrophic Mesodinium rubrum was only observed in the northern hemisphere and tropical waters. Its maximum abundance was observed at 48°N (1080 cells l−1, 1.14 μg C l−1). The most frequently observed ciliates were oligotrichs and choreotrichs. Other important ciliates were haptorids (including M. rubrum) and hypotrichs.

Planktonic ciliate communities in a semi-enclosed bay of Yellow Sea, northern China: annual cycle

To reveal the annual patterns of planktonic ciliate communities, planktonic ciliate species composition, abundance and biomass, and responses to environmental conditions, were investigated during an annual cycle in Jiaozhou Bay, Qingdao, northern China. A total of 64 species belonging to five orders (Oligotrichida, Haptorida, Cyrtophorida, Hypotrichida and Tintinnida) were identified, 9 of which were dominant. Ciliate communities presented a clear seasonal pattern in terms of both abundance and biomass. A single peak of ciliate abundance and biomass occurred in late August, mainly due to the oligotrichids, tintinnids and haptorids. The 9 dominant species showed a distinct temporal distribution with seasonal successions of ciliate communities. Multivariate analyses revealed that ciliate abundance was significantly correlated with water temperature, dissolved oxygen and nutrients, especially nitrate nitrogen and soluble reactive phosphate (P < 0.05). These findings provided basic data on annual cycle of planktonic ciliate communities in a semi-enclosed bay of Yellow Sea, northern China.