This study identifies the ecological status of lakes which are significant water bodies located within Polish national and landscape parks. The assessment carried out on the basis of data from the National Environmental Monitoring System coming from 2010-12 took into account the requirements of the Water Framework Directive (WFD). Half of the lakes analyzed were characterized by at least good status, while the others were in moderate or even poor or bad status, although they were situated in protected areas. The study shows multi-aspect (morphometric, hydrological, and catchment-related) factors that determine the water quality and the status of the lake ecosystem. A strong correlation was found between eutrophication indicators (chlorophyll a concentration, water transparency, nutrient concentrations in water) and the majority of limnological parameters of lakes. There was no direct relationship between the percentage shares of the major land uses of lake catchments and the ecological status of lakes, but the nitrogen and phosphorus load theoretically emerging in the catchment correlated with the nutrient concentrations in water, as well as with chlorophyll a and water transparency. On the basis of data available, it proved impossible to identify a positive impact of covering lakes with protection within a national or landscape park on their ecological status.
This paper outlines the Phytoplankton Multimetric for Polish Lakes (PMPL) – an ecological status assessment method which can be used to implement the European Water Framework Directive (EC, 2000). The PMPL includes abundance parameters of phytoplankton: the metrics: “chlorophyll a”, “total biomass” while the taxonomic composition is partly evaluated by the metric “biomass of cyanobacteria”. All of these three single metrics as well as the final PMPL index values are the same scale and range from 0 to 5. The PMPL can be transformed to a normalized Ecological Quality Ratio (EQR) range from 0 (the worst status) to 1 (the best status). The PMPL method differentiates “stratified” and “unstratified” lake types as well as subdivisions into lakes characterized by a high (>2) or low (<2) lake volume-to-catchment area ratio (VQ). The metrics used and the PMPL index respond to eutrophication pressure expressed by total phosphorus and total nitrogen concentration, the significance of the relationships depends on the tested parameter and the abiotic type of lake. From among the single metrics, the metric “chlorophyll a” was usually found to reveal the strongest significant correlation to both total phosphorus and total nitrogen (Spearman`s coefficient varied from –0.41 to –0.75 and from –0.34 to –0.56, respectively). The weakest correlation with nutrients was noted for metric “biomass of cyanobacteria” (R=–0.13 to –0.62). The PMPL correlated best with TP and TN in unstratified lakes (R=–0.49 to –0.70). The testing of the PMPL index shows a statistically important distinction between Good/Moderate ecological status and confirmed designated boundaries of High/Good and Good/Moderate states.
During studies of phytoplankton in Sumin Lake (Łęczna-Włodawa Lakeland), conducted from May till September 2001 and 2002, 15 taxa of the genus Pediastrum (Hydrodictyaceae, Sphaeropleales) were found. Among them there were common species as Pediastrum boryanum, P. duplex, P. tetras and P. simplex, but also rare species as P. integrum or P. kawraiskyi. An especially interesting species was P. orientale, the taxon that until now has not been noted in phytoplankton of Polish water bodies. The paper gives descriptions of the genus Pediastrum coenobia and physico-chemical conditions of the habitat. The original documentation of Pediastrum taxa is added.
A new phytoplankton-based method (the Phytoplankton Metric for Polish Lakes – PMPL) for the ecological status assessment of lakes has been developed in Poland. This method has not been validated and tested on independent data, hence the aim of the study was to check the applicability of this method and the sensitivity of different phytoplankton metrics along pressure gradient. Phytoplankton data were collected from 33 Polish lowland lakes (20 stratified, 13 non-stratified), during the growth season in the period from 2005 to 2009. The biomass of phytoplankton was calculated from cell volume measurements and chlorophyll a concentration was determined spectrophotometrically by the alcohol method. Total nitrogen and total phosphorus concentrations were determined by standard methods (PN-EN ISO 6878:2006p.7 and PN-EN 25663:2001, respectively) and water transparency was measured using a Secchi disk. For comparability, an ecological status was determined according to three phytoplankton- based methods: Polish, German and Hungarian. Polish metrics showed a strong correlation with the other metrics (German, Hungarian), which are broadly and successfully used for assessment in Europe. However, a statistically significant correlation was found between all the metric values and the main parameters: total phosphorus, total nitrogen and Secchi disk visibility. The metrics based on quantitative phytoplankton features were more sensitive to the growth of eutrophication than others, based on indicator taxa. Total phosphorus demonstrated a stronger relationship with the tested metrics than total nitro gen. Phytoplankton metrics reacted quite well to pressure gradients because of the decreasing tendency of metric values along the TP and TN gradient and an increasing tendency along the Secchi disk visibility gradient. The multimetric PMPL may be recommended as useful for the assessment of the ecological status of Polish lakes.
The paper presents the results of a study on allelopathic effect of extracts from Stratiotes aloides on natural lake phytoplankton communities grown outdoor in 40 l containers under natural light conditions. The water and plants were taken from an oxbow lake in spring (when S. aloides plants were submerged) and in summer (when plants were floating on lake water surface). Water extracts were prepared from fresh healthy leaves obtained on both sampling occasions. Control containers were supplemented with N and P in amounts similar to those introduced to experimental containers with macrophyte extracts. That way the experimental set up excluded the possibility of phytoplankton limitation by nutrients. Under such conditions the extracts from S. aloides strongly reduced phytoplankton biomass measured as the concentration of chlorophyll a (from 370 to 141 mg chl. a m⁻³ in spring and from 266 to 50 mg chl. a m⁻³ in summer). The inhibition of phytoplankton growth was indirectly confirmed by higher concentrations of available nutrients in experimental versus control containers. The extracts affected also the spring phytoplankton community structure by selective inhibition of diatoms and, to a less extent, of green algae and Cryptophyceae. Similar response of phytoplankton biomass to extracts obtained from submerged and floating S. aloides might suggest that allelochemicals were the constitutive part of macrophyte tissue and their production was not induced by competition between macrophyte and algae.
The composition and abundance of cyanobacteria in three lakes of the Polesie Lubelskie (East Poland) were studied in summer periods. Vertical distribution of these algae was analysed in two depths – in epilimnion and deoxygenated metalimnion. Species composition and domination was similar for these two sites. It means that the species like: Limnothrix planctonica (Wołosz.) Meffert, Limnothrix redekei (Van Goor) Meffert, Planktothrix agardhii (Gom.) Anagn. et Kom., Woronichinia naegeliana (Unger) Elenk. and Microcystis viridis (A. Braun in Rabenhorst) Lemm. are not affected by turbulence of water as well as by oxygen conditions.
Studies were carrying out in two shallow (mean depth ≈ 0.3 m) and small (area 2.7–8.2 ha) river lakes, which were flooded by water of River Bug (Eastern Poland) once a year (in spring). The species composition, biomass of phytoplankton and concentration of chlorophyll awere studied. Samples were taken in June (after flooding) and in August (after three months of isolation from river water). About 150 species of phytoplankton were determined. After the flood period phytoplankton biomass was dominated by nannoplankton belonging to Cryptophyceae and Chrysophyceae (strategy-r) and in the stabilization period by microplanktonic green and blue–green algae (strategy-K). The higher biomass and concentration of chlorophyll a values were noted in August than in June. The differentiation of phytoplankton was also stated between near-by stations in both lakes.
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