Mirosław Grzybowski

Effects of lateral connectivity on zooplankton community structure in floodplain lakes

Hydrological conditions are responsible for the changes in lateral connectivity between the main river channel and the floodplain lakes, a factor controlling zooplankton abundance and diversity. We tested the hypothesis that the degree of connectivity between the aquatic habitats and the river channel governs the zooplankton densities and community structure. Abundances, community composition and species diversity of zooplankton were analysed against the gradient of lakes’ connectivity and the water quality parameters under a natural flood pulse in the Biebrza River (North-Eastern Poland). Our findings revealed that the water level fluctuations directly affect the availability of nutrients, aeration, what in turn controls the densities and biovolumes of zooplankton communities. Along with the increase in the lake isolation, the taxonomic diversity of zooplankton decreased, while the eudomination of taxa indicative of advanced trophy (Rotifera) was observed. Qualitative parameters, as number of species, diversity and richness, were significantly higher at mean water levels, which supports the intermediate disturbance hypothesis. The sensitivity of the zooplankton community to variable hydrological conditions and lateral connectivity gradient demonstrates its potential as an unexploited indicator of any habitat changes in the aquatic ecosystems.

Variations in the population structure and ecology of Matteuccia struthiopteris

The aim of the study was to investigate variation in the structure of a population of Matteuccia struthiopteris (L.) Tod. in N–E Poland depending on its location in a river valley and light availability under tree canopies. Ordination statistical methods and structural equation modeling were used to identify ecological relationships in the population. The analysis showed that optimum growth conditions of M. struthiopteris depend on the canopy cover. As the shading increased, the size of trophophyllous leaves and the production of sporophylls decreased. The relationship between the canopy cover and the optimum growth conditions was best expressed by rootstock diameter and, to a lesser extent, by the number and height of trophophylls. An indirect relationship between the number and height of sporophylls and the canopy cover, by rootstock size and trophophyll quantity, was also identified. This relationship may be caused by the predominance of vegetative forms of reproduction. Based on the correlations between the landscape position vs. rootstock diameter and trophophyll height, a difference in the habitat colonization potential of M. struthiopteris could be detected. Three spatial clusters of M. struthiopteris in the river valley were identified: river bank, river terrace, river valley slopes. These relationships and the distribution of other herbaceous plant species occurring at the plots indicate that the distribution pattern of M. struthiopteris in the study area is determined by diverse environmental conditions, however mainly by light conditions.

Natural dimictic and polymictic lakes: similarities and differences in relationships among chlorophyll, nutrients, Secchi depth, and aquatic macrophytes

Fourteen lakes, situated in the Borecka Forest, Poland and including 8 dimictic and 6 polymictic lakes, were investigated over a period of 10 years. The water bodies were at low risk from eutrophication. A positive and statistically significant correlation between total phosphorus (TP) and total nitrogen (TN) concentrations and chlorophyll levels was reported in all of the studied lakes. The results of the study validate the hypothesis that aquatic vegetation in lakes may have a delayed response to nutrient supply because the phosphorus delivered to and present in lakes may be partially unavailable for producers. Redundancy analysis (RDA) results revealed a significant correlation between relative plant abundance and chlorophyll concentrations and a weaker relationship with the remaining lake parameters (TP, Secchi depth, TN). The positive correlation between chlorophyll and seston concentrations was significant only in dimictic lakes (r = 0.62, p = 0.001). In polymictic water bodies, chlorophyll levels decreased with Secchi depth, whereas chlorophyll concentrations in dimictic lakes varied irregularly with an increase in water transparency. The correlation between seston and Secchi depth was significant in all lakes. Seston distribution in response to a drop in water transparency did not differ significantly between the lake types. The analyzed parameters supported the identification of two groups of lakes which correspond to habitat types of the Natura 2000 network.

Ecomorphological evaluation of the Łyna River along the Kotowo-Ardapy section

Ecomorphological evaluation of the Łyna River along the Kotowo-Ardapy section The Water Framework Directive of the European Parliament and the European Union Council No 2000/60/EC, of 23rd October 2000, on the common water policy, modifies provisional rules of river monitoring. Being an EU country, Poland has been obliged to introduce the new regulations and, additionally, to elaborate and implement regional methods for hydromorphological assessment of quality of river water no later than 2006. In the present study, hydromorphological evaluation of the Łyna River along a 7-km-long section between Kortowo and Adrapy has been completed. Along this section, the Łyna is a lowland, gravel and highly natural river. Two methods of evaluation, based on different assumptions, were applied. One is a British method, called River Habitat Survey (RHS), whereas the other one is based on German methods, known as ecomorphological river evaluation, and has been developed by Ilnicki (University of Agriculture in Poznań). A comparative analysis of the usefulness of both methods was performed, based on the results obtained with each method. The scope of our study has been to include a survey of the flora, phytosociological relationships and fauna of the river and its environs. Both methods implied that the river was more natural upstream and the results are shown on maps. The ecomorphological river evaluation, according to Ilnicki, assesses the river along its entire course, which is in accord with the Directives assumptions. In contrast, the RHS method, which analyses selected, 500-meter-long sections, results in a non-continuous river evaluation. I our study, the assessment by RHS led to the omission of the most valuable section of the river. However, RHS (owing to the HQA index) more accurately indicates anthropogenic influences on the river, unlike the ecomorphological evaluation by Ilnicki, which lacks such an index. Consequently, the estimation of the degree of naturalness or extent of man-made pressure is not free from some subjectivity, which means that the surveyor needs certain experience. The RHS method is objective and unambiguous but still needs adaptation to the Polish conditions. Both methods can be statistically elaborated. At present, it is difficult to compare the reliability of the results obtained by both methods. The RHS method requires an application of a reference group of rivers, which has not been prepared for Poland yet. Assuming that the RHS database on the examined rivers (the Department of Ecology and Environmental Protection, August Cieszkowski Agricultural University in Poznań) could correspond to that missing reference group for Polish rivers, the results obtained by both methods were comparable.

Nickel in the muscle tissues of freshwater fish from north eastern Poland should not cause human health concerns

Excessive intake of nickel (Ni) is known to produce adverse health effects in humans, including carcinogenicity and allergenicity. The main route of exposure for humans is diet, including fish. There is, however, little information concerning Ni content in freshwater fish in Poland. The aim of the study was to determine the concentrations of Ni in meat tissues of three fish species from north eastern Poland and assess toxic potential to healthy and susceptible sub-groups of individuals. The settings for the study lakes span a range of anthropogenic influence from protected areas to a basin with a town and several villages and another one influenced by a pesticide tomb leakage. Fish were netted and kept frozen until analysis. After defrosting, the fish were filleted and minced. The ashed samples were dissolved in nitric acid and analyzed for Ni by flame atomic absorption spectrometry. Roach meat contained 6.6–23 µg kg−1 Ni, bream 9.5–178 µg kg−1, and carp 16.5–139 µg kg−1. These concentrations are low, indicating that the fish were not excessively contaminated with the metal. Consuming a 250 g portion of fish would result in an average nickel intake of 4 µg for roach, <10 µg for bream, and <20 µg for carp. These values represent only 0.4–2% of the maximum level that is likely to pose a risk of adverse effects as established in the USA. Consumption of fish from the study region need not necessarily pose a health threat.

The state of plant conservation in small water bodies located within the city limits of Olsztyn

The state of plant conservation in small water bodies located within the city limits of Olsztyn The interior depressions in the Olsztyn area are characterized by high biodiversity. On the basis of floral surveys of 32 small water bodies, 200 species of vascular plants and 10 species of bryophytes were recorded. Phytosociological analysis indicated 45 plant associations. Among the phytocoenoses described, some communities require more attention, including Wolffietum arrhizae, Riccietum fluitantis, Charetum fragilis, the pondweeds Potametum nitentis and P. commpressi as well as communities with Potamogeton trichoides and P. pusillus. In light of their significant natural value, some of the basins studied units should be protected as ecological grounds. Reservoirs located in the Jaroty District, in the vicinity of Lake Track or some reservoirs located within the Gutkowo and Kortowo districts are important points of peatwater or water accumulation. These small water bodies limit the nutrient and pollutant input into the numerous lakes located in the Olsztyn area. Some basins are of a recreational character, including the reservoir located in the central quarter of the town and the water bodies of the Kortowo District. The remaining reservoirs need restoration and litter collection to restore their recreational functions.

Lead and cadmium content in the meat tissues of fish from water ecosystems in the vicinity of a pesticide tomb

Lead and cadmium content in the meat tissues of fish from water ecosystems in the vicinity of a pesticide tomb Lead and cadmium levels were determined in the meat tissues of roach, bream, and carp netted in a lake and in fish ponds threatened by a pesticide tomb and in control basins in northeastern Poland. Concentrations in roach ranged from 20 to 124 μg kg-1 of Pb and from 1 to 19 μg kg-1 of Cd. In bream they were from 4 to 280 μg kg-1 of Pb and 2 to 28 μg kg-1 of Cd, while in carp they were from 9 to 82 μg kg-1 of Pb and 2 to 260 μg kg-1 of Cd. The metal concentrations were low; no result exceeded admissible residue levels set forth by Polish law, and no evident contamination of fish by leakage from the pesticide tomb was detected.