Use of rotifer trophic state indices to show the effect of hydrobionts and nutrients on water trophic status in mesocosms

We have determined how Crustacea, zebra mussels (Dreissena polymorpha), fish and nutrients affect the trophic state in mesocosms filled with water collected from the pelagic zone of a eutrophic lake. We hypothesized that the pool of nutrients would increase both directly due to the input of phosphorus and nitrogen and/or indirectly due to the introduction of animal biomass. We used trophic state indices based on the abundance and species structure of rotifers to assess changes in the trophic state in mesocosms. The role of small detritophages in rotifer communities increased as a result of treatments. Our results clearly demonstrated that D. polymorpha was able to reduce the trophic status of mesocosm waters as indicated by reduced rotifer trophic state indices regardless of interactions with other treatment factors. Contrary to our expectations, neither the nutrients added at the beginning of the experiment nor the introduction of crustaceans or fish affected the rotifer trophic indices.

Rotifers in Heated Konin Lakes—A Review of Long-Term Observations

The Konin lakes, heated by power stations and invaded by alien organisms, are a natural laboratory in which we can study the impact of climate change on the native communities of aquatic organisms. The aim of our study was to assess the impact of water heating and the occupation of the littoral zone of the lake by invasive species Vallisneria spiralis on changes in the species structure of rotifer communities of plankton, epiphyton and psammon. The archival material was used from the years: 1970–1975, 1978 and 1983, and compared with the results of studies conducted in Licheń and Ślesin Lakes in the years 2010–2011 and 2017–2018. It has been shown that the heating of waters of the studied lakes, combined with the shortening of their retention time, as well as the invasions of alien species, have caused significant changes in the taxonomic and trophic structure of plankton rotifers. In inhabiting Vallisneria bed epiphytic rotifer communities, the share of alien species did not increase, but relatively high densities of uncommon sessile species still persist. Psammon communities in the lakes are dominated by monogonont species relatively common in this habitat in nonheated lakes, but they are nearly devoid of bdelloids, which are abundant in psammon of Masurian lakes.

Seasonal Differences in Taxonomic Diversity of Rotifer Communities in a Hungarian Lowland Oxbow Lake Exposed to Aquaculture Effluent

With the intensification of aquaculture technologies, the amount of feed input and waste material is increasing, creating potentially negative impacts on freshwater habitats receiving effluent from such systems. Changes in biodiversity of zooplankton communities is often used to assess the effects of such impacts. Rotifers are suitable for bioindication of water quality due to their fast reaction to environmental changes. We examined seasonal changes in the diversity of rotifer communities along a 3.5 km section of the biggest oxbow lake in the Tisza River basin, Hungary, that received inflow from an intensive tank-based aquaculture farm. We detected a species-rich rotifer community with 26 species. Using the Rényi one-parameter diversity index families, we found that biodiversity increased away from the point of inflow in spring, but after a summer transition period the situation became partially reversed during autumn. At the beginning of the study period, the nutrient-rich effluent strengthened the dominance of common species, which decreased but did not disappear in summer. In autumn, the extra nutrient input delayed the decline of the rotifer community at the point of effluent.

Effect of underground salty mine water on the rotifer communities in the Bolina River (Upper Silesia, Southern Poland)

The research was carried out in the Bolina River, which is the most anthropogenically saline river in Europe, from 2017 to 2018. This river flows through the highly industrialised and urbanised part of Upper Silesia (Poland). The aims of our survey were to analyse the structure of the rotifer communities and to determine the most important environmental factors that have a significant impact on their structure in a river under the influence of underground salty mine water discharge. According to a canonical correspondence analysis (CCA), the rotifer communities in the Bolina River are affected by electrical conductivity, the temperature of the water and the concentration of phosphates. An increase in the electrical conductivity (salinity) in the lower course, which was the result of salty mine water discharge into the Bolina River, was reflected by a decrease in the median density, the number of rotifer taxa and the Shannon–Wiener index H′. The Bolina River is a unique habitat for halophilic rotifers as well as a site of the occurrence of rotifers that can also develop in winter.

Ecology of moss-dwelling rotifers in a raised bog: Differentiation of rotifer communities in microhabitats

Peat bogs play key roles in preserving the stability of ecological relationships, but are some of the fastest disappearing and most endangered ecosystems in Europe. The aims of this study were: (1) to compare the distribution, species richness, diversity, and density of rotifers in microhabitats of a raised bog; and (2) to verify the hypothesis that rotifer density and species composition are dependent on seasonal factors, moss moisture content, and the dominant species of mosses in the microhabitats. Sampling was done monthly from April to November in 2013–2014 in the bog Moszne in eastern Poland (51°27′28.7″ N, 23°07′15.8″ E). The microhabitats sampled included hummocks, slopes, and hollows. A total of 40 rotifer taxa were identified. The highest species richness occurred in the hollows (40), dominated by