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Long-term changes in phytoplankton and macrophyte communities in an eutrophic shallow reservoir and prospects for its restoration

Rusanov Alexander, Trifonova Irina, Ignatyeva Natalia, Pavlova Oksana

Oceanological and Hydrobiological Studies

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2020

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Vol. 49, No. 2

168--183

EN

Long-term changes in hydrochemistry and community structure of phytoplankton and macrophytes were analyzed in the Sestroretskiy Razliv reservoir (northwestern Russia). The average content of total phosphorus (TP) in May–October increased from 73 μg P l-1 in 1980 to 163 μg P l-1 in 2000. A significant increase in average chlorophyll a content from 16.6 μg l-1 in 1980 to 84.7 μg l-1 in 2000 and a shift in phytoplankton composition to the dominance of cyanobacteria over diatoms indicated a change in the trophic status of the reservoir from meso-eutrophic to hypertrophic. In 2016 and 2018, average TP was 96 and 101 μg P l-1, respectively. The average content of chlorophyll a was 43.6 μg l-1 in 2016 and 66.6 μg l-1 in warmer 2018, indicating persistent eutrophic conditions. Diatoms dominated both in 2016 and 2018, especially in 2016 characterized by unfavorable weather conditions. Cyanobacteria were more abundant in 2018 with higher summer temperatures. The decline of the total area covered by aquatic vegetation from 157 ha in 1980 to 76 ha in 2016 likely resulted from an increase in phytoplankton biomass and water turbidity. Based on the results of our observations, in addition to further reduction in nutrient loading, biomanipulation by introducing predatory fish as a restoration measure was proposed to improve the ecological status of the reservoir.

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Long-term changes in water quality and ecological status of lakes in the Wielkopolska National Park and its buffer zone with special reference to effectiveness of the lakes’ protection

Ławniczak A. E.

Oceanological and Hydrobiological Studies

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2016

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Vol. 45, No. 4

524--538

EN

This paper evaluates water quality and ecological status of lakes located in the Wielkopolska National Park and its buffer zone. Changes in water quality were analyzed from 1974 to 2012 in order to assess the effectiveness of the protection strategies implemented on the studied lakes since 1957, i.e. the date when the park was established. The ecological status of the lakes was assessed with the use of macrophytes as well as hydromorphological and physicochemical analyses performed in 2012. Changes in water quality of the studied lakes within the last 40 years were analyzed based on available published and unpublished data, as well as field studies. All water bodies are characterized by advanced eutrophication. However, evaluation of the ecological status showed good status of the charophyte-dominated lakes, i.e. Lake Wielkowiejskie and Lake Budzyńskie. Lack of significant differences in physicochemical water qualities between the park and its buffer zone indicated that measures implemented to protect the water, particularly in the park, are ineffective. This study shows that more radical conservation measures are necessary to protect and improve the water quality, not only in WPN and its buffer zone but also in the whole catchment area.

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Effects of lake transparency on diversity of microhabitats for chironomid communities

Tarkowska-Kukuryk M.

Polish Journal of Ecology

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2014

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Vol. 62, nr 3

575--588

EN

The study investigated the effect of microhabitat (emergent/submerged macrophytes) within lakes of different status (transparent/cloudy water) on the diversity and distribution of chironomid assemblages. Field and laboratory studies were undertaken bimonthly, from January to November 2008, in two shallow lakes of Polesie Lubelskie (eastern Poland), transparent water and cloudy water lake. The main objectives of the study were to compare the density and taxonomic richness of chironomids associated with emergent and submerged macrophytes within lakes of extremely different environmental conditions and to recognize the most important variables affected chironomid distribution between microhabitats within lakes. In transparent water lake, number of chironomid taxa varied between 12 (emergent macrophytes) and 18 taxa (submerged macrophytes) and was significantly higher than in cloudy water lake, 6 and 8 taxa, respectively. Mean abundance of chironomids associated with emergent macrophytes was higher in cloudy water lake. The opposite relation was observed on submerged macrophytes. The PCA analysis showed visible distinction of chironomid assemblages between microhabitats and lake types. The results of RDA led to determine the significant variables (Monte-Carlo permutation test) affected chironomid distribution. In both, transparent and cloudy water lake, the significant variables responsible for chironomids distinction between microhabitats were density and biomass of macrophytes, biomass of periphytic algae and pH. Moreover, nutrients, N-NO3 (transparent water lake) and P-PO4 (cloudy water lake), showed the significant influence.