Macrophyte communities as indicators of the ecological status of drainage canals and regulated rivers (Eastern Poland).

Macrophytes are one of the biological elements for assessing the ecological status. Macrophyte communities were studied in six artificial (drainage canal and ditches) or modified watercourses (regulated rivers). In order to assess the ecological status of the watercourses, studies were carried out with the use of the Macrophyte Index for Rivers (MIR) proposed in the Water Framework Directive. Macrophyte communities were mainly represented by helophytes (12 species in total), and the highest percentage area cover (50-75% of the site) was observed for pleustophytes (Lemna spp.). Macrophytes communities were affected by the gradients of hydromorphological (canal modification, flow type, and shading) and parameters water quality (nutrients and water transparency). The relationships were highly species-specific. In accordance with the MIR values, the ecosystems were classified as having poor (drainage canal), moderate (regulated rivers), or good (drainage ditches) ecological status.

Long-term responses of epiphytic midges (Diptera, Chironomidae) to emergent macrophytes removal and P concentrations in a shallow hypertrophic lake ecosystem.

Chironomid larvae are used as indicators of environmental changes in neolimnological and paleolimnological research. In the present study, we evaluated the responses of epiphytic chironomids to changes in environmental conditions over a long time scale. We intended to decipher whether changes in the trophic status of a lake (hypertrophic-eutrophic) would affect the taxonomic structure of epiphytic chironomids by influencing their food availability (structure of periphytic algae) and whether the responses of chironomids are taxa specific. In a shallow hypertrophic lake ecosystem, epiphytic chironomids associated with the emergent macrophyte Phragmites australis were studied from 2001 to 2018. In the autumn of 2006, emergent macrophyte removal led to an improved water transparency and reduced phytoplankton biomass. Epiphytic chironomids responded clearly to the shift from hypertrophic to eutrophic conditions. Under hypertrophic conditions larvae of detritivorous Cricotopus sp. (gr. sylvestris) and filter-feeder larvae of Glyptotendipes sp. prevailed. After macrophyte removal, we observed high relative abundances of Endochironomus albipennis and Paratanytarsus austriacus, which are classified as grazers, utilise periphytic algae (mainly diatoms) as a food source. The results indicated that the density of P. australis, relative abundances of cyanobacteria and diatoms in periphyton communities, Secchi disc depth, and periphytic and planktonic Chl-a are significant determinants of the diversity of epiphytic chironomids. The results can provide a reliable reference to the neolimnological and paleominological studies on chironomid responses to multiple environmental stressors in shallow lakes.

Algal characterization and bioaccumulation of trace elements from polluted water.

Algae are a group of autotropic and eukaryotic organisms that play a significant role in the food, pharmaceutical, cosmetic, fuel, and textile industries. They are an important part of our ecosystem, and they can help control the growing problem of pollution. In this work, the carotenoid, sterol, polyphenol and mineral content, spectral and thermal characteristics of six common river algae, viz. Chara spp., Hydrodictyon spp., Lyngbya spp., Nitella spp., Pithophora spp., and Spirogyra spp., collected from Kharun river (India), were evaluated. The concentration of oil, total polyphenols, flavonoids, and mineral ranged from 0.4 to 4.3%, from 2705 to 4450 mg/kg, from 1590 to 2970 mg/kg, and from 85,466 to 122,871 mg/kg of algae (dw), respectively. The concentration of carotenoids and sterols varied from 1.6 to 109 mg/kg and from 522 to 35,664 mg/kg. The potentiality towards the bioaccumulation of 22 trace elements from the surface reservoir was assessed and discussed in relation to carbonate inlay of the algae wall and to the ions ability to bind to pectin, polypeptides, carotenoids, polyphenols, and flavonoids, on the basis of infrared spectroscopy data. In view of the extremely high enrichment factors found for certain elements, such as P, Co, Cu, Pb, and Fe, some of these algae hold promise as bioindicators for the detection of these elements in aquatic environments. Ordination analysis was used to measure the variance gradient of the algal data.

Effects of experimental addition of nitrogen and phosphorus on microbial and metazoan communities in a peatbog.

Interactions between microbial communities and the classical grazing food chain are essential for understanding the functioning of peatbog ecosystems. However, little is known of how short-term intensification of eutrophication processes may influence microbial and metazoan communities in transitional peatbog. We addressed the hypothesis that an increase in the concentration of nutrients will affect the species richness and abundance of microorganisms and small metazoans and cause changes in the food web structure in a peatbog. The experiments were performed in a transitional peatbog. Four experimental variants were conducted (control and nutrient-enriched: +P, +N and P+N). Increased habitat fertility was found to modify the taxonomic composition and functioning of microbial communities. We observed a strong reduction in the species richness of testate amoebae-top predators, and a substantial increase in the abundance of bacteria, flagellates and ciliates. A better understanding of which parameters regulate microbial populations in peatbogs is critical for more accurate prediction of how peatbogs will respond to global climate change or anthropogenic disturbances.

Microbial Communities as Environmental Indicators of Ecological Disturbance in Restored Carbonate Fen-Results of 10 Years of Studies.

Interactions between bacteria and protists are essential to the ecosystem ecology of fens. Until now, however, there has been almost no information on how restoration procedures in carbonate fens affect the functioning of microbial food webs. Changes in vegetation patterns resulting from restoration may take years to be observed, whereas microbial processes display effects even after short-term exposure to changes in environmental conditions caused by restoration. Therefore, microbial processes and patterns can be used as sensitive indicators of changes in environmental conditions. The present study attempts to verify the hypothesis that the species richness and abundance of microbial loop components would differ substantially before and after restoration. The effect of restoration processes on the functioning of the food web was investigated for a 10 years in a carbonate-rich fen, before and after restoration. The restoration procedure (particularly the improvement in hydrological conditions) distinctly modified the taxonomic composition and functioning of microbial food webs. This is reflected in the increased abundance and diversity of testate amoeba, i.e. top predators, within the microbial food web and in the pronounced increase in the abundance of bacteria. This study suggests potential use of microbial loop components as bio-indicators and bio-monitoring tools for hydrological status of fens and concentrations of nutrients. Better understanding of what regulates microbial populations and activity in fens and unravelling of these fundamental mechanisms are particularly critical in order to more accurately predict how fens will respond to global change or anthropogenic disturbances.

Effects of rotifers, copepods and chironomid larvae on microbial communities in peatlands.

Interactions between the microbial loop and the classical grazing food chain are essential to ecosystem ecology. The goal of the present study was to examine the impact of chironomid larvae, rotifers and copepods on the major components of the microbial food web (algae, bacteria, heterotrophic flagellates, testate amoebae and ciliates) in peatlands. Two enclosure experiments were carried out in a Sphagnum peatland. In the experiments we manipulated rotifers, copepods and macroinvertebrates, i.e. chironomid larvae (Psectrocladius sordidellus gr). During the experiments variation was observed in the abundance of potential predators. The beginning of the first experiment was distinguished by dominance of rotifers, but five days later copepods were dominant. In the second experiment copepods dominated. The results of this study are the first to suggest a substantial impact of chironomid larvae, rotifers and copepods on microorganism communities in peatland ecosystems. The impact is reflected by both a decrease in the abundance and biomass of testate amoebae and ciliates and a transformation of the size structure of bacteria. Heterotrophic flagellates (HNF) were not controlled by metazoans, but rather by testate amoebae and ciliates, as HNF were more abundant in the control treatment.