Polish River Basins and Lakes – Part II

This study presents the results of a long-term study of periphyton inhabiting submerged parts of shoots of Phragites australis, carried out in the ecosystems of northern Poland (lakes, rivers, oxbows and a dam reservoir). The development of epiphytic organisms representing the level of producers and consumers was found on the substrate formed by the reed in each of the studied aquatic ecosystems. The coastal lake was characterized by the highest taxonomic diversity and the smallest oxbow lake undergoing restoration. In the autotrophic fraction, Bacillariophyta predominated in the studied ecosystems and were accompanied by very high amounts of chlorophytes and Cyanobacteria. Phytoperiphyton had the highest abundance in lakes (~40 mln cells m⁻²) and the lowest in rivers (~7 mln cells m⁻²). Among the heterotrophic fraction, there were 14 taxa in the lakes and only 9 taxa in the dam reservoir. Zooperiphyton reached the highest abundance in lakes (~140 thousand indiv. m⁻²) and were the lowest in the dam reservoir (~7 thousand indiv. m⁻²). The largest share in the microperiphyton was reached by Protista (~60%) and Rotifera (~20%), while the lowest abundance were representatives of Cladocera (~2%) and Oligochaeta (~1%). Macrozooperiphyton were represented primarily by Chironomidae larvae (~75%). The structure and abundance of periphyton may indicate the trophic state of individual aquatic ecosystems, which is important in determining their ecological condition according to the Water Framework Directive.

The directional changes of phytoplankton in Polish lakes were presented to show some tendency concerning the total biomass, composition, and biodiversity as related to environmental variables. The selected lakes were analyzed concerning various types of antropopressure, e.g., relatively low, medium, and huge human impact including sewage inflow history, different hydrological regime nature as natural phenomenon of flow-through lakes and as a consequence of artificial including into water-cooling system with short retention time, and different restoration actions (biomanipulation and artificial aeration).

Smaller biomass and more varied structure of phytoplankton (co-dominated by Bacillariophyta, Cryptophyta, Miozoa, and Cyanobacteria) were typical of the PEG Model for mesotrophic or even oligotrophic temperate lakes with lower trophy level. On the contrary, a large biomass with Cyanobacteria domination in summer was typical in more eutrophied lakes. The prominent dominants were primarily chroococcalean Microcystis aeruginosa and M. wesenbergii and filamentous Planktolyngbya limnetica, Pseudanabaena limnetica, Limnothrix redekei, and Planktothrix agardhii. Species richness and values of biodiversity index were usually higher in more eutrophied lakes than in mesotrophic lakes. The overall relationships of phytoplankton groups with environmental variables indicated that water transparency in less eutrophied lakes while water temperature and nutrient concentrations in more eutrophied lakes induced phytoplankton growth.

Although ponds located in a low-transformed landscape harbour higher biodiversity than ponds in areas with a large impact of anthropopression, both types of water bodies can contribute to the enrichment of fauna on local and regional scales. This review presents aspects of pond zooplankton diversity with reference to the occurrence of species, common and rare, and significant drivers of their distribution. The results of various studies carried out on small water bodies in Poland revealed a great level of zooplankton diversity, which points directly to a high variation of the origin of types of ponds. Land use within the direct catchment area influences the creation of zooplankton diversity, although a greater impact is connected with various habitats, particularly the open water zone and macrophyte-dominated areas. The complex architecture of elodeids is responsible for the highest zooplankton diversity with many rare species, offering a great number of available ecological niches for littoral animals and profitable anti-predator conditions for planktonic species. Therefore, one should strive to maintain or even increase the complexity of aquatic vegetation within even small-surfaced ponds. The generally high share of rare species found in ponds underlines their high ecological value but, at the same time, a lack of thorough studies. The most common rotifers found in Polish ponds were Keratella cochlearis, Anuraeopsis fissa, Polyarthra vulgaris and Keratella quadrata as well as Chydorus sphaericus, Bosmina longirostris, Ceriodaphnia quadrangula and Eubosmina coregoni among crustaceans. This reflects the wide ecological valence of these species and suggests that most ponds are eutrophic.

Pelagic zooplankton communities are structured by ecological processes, like dispersal, and by biotic interactions and abiotic environmental conditions. In this paper we study a role of the processes in structuring zooplankton communities in relation to a character of connections between lakes in their systems. Studies were carried out in five lake systems in northeast Poland: the Great Masurian Lakes, lakes of the Krutynia River watershed, harmonic and dystrophic lakes in the Wigry National Park, and lakes in the Suwałki Landscape Park. Pelagic waters of all the studied lakes involved 89 ciliate, 129 rotifer, 40 cladoceran, and 22 copepod species. Forty-seven rotifer species were littoral, occasionally occurring in the pelagial. In four harmonic lake systems, there were the same most frequent species: among are rotifers Keratella cochlearis (100% frequency) and present in more than 75% Ascomorpha saltans, Asplanchna priodonta, Collotheca mutabilis, Gastropus stylifer, Kellicottia longispina, Keratella quadrata, Polyarthra major, P. remata, and P. vulgaris and crustaceans Daphnia cucullata and Diaphanosoma brachyurum. Among ciliates, the most common and frequent (100%) species for two harmonic lake systems was Rimostrombidium humile. Dystrophic lakes in the Wigry National Park had a completely different list of the most frequent ciliate and rotifer species, among which only one ciliate (Halteria grandinella) and one rotifer species (Polyarthra remata) occurred in more than 75% of the lakes. Our results suggest that the role of dispersal processes in structuring zooplankton communities is particularly important in the system of lakes that are connected directly or by short channels.

Biodiversity is a significant element that describes the ecological state of waterbodies. Eutrophication is a widespread problem that has an impact on water habitats and leads to the succession of sensitive species. Habitat degradation results in significant, predictable decreases in taxonomic diversity. We assessed benthic macroinvertebrate community structure (mainly families) in 9 rivers, 9 ponds, and 23 lakes in northeastern Poland. Mollusca, Annelida, Arthropoda, and Nemathelminthes were the 4 phyla represented, and 76 Insecta families, 5 taxa of Crustacea, and 12 Mollusca families were identified. A total of 91 taxa (mainly families) were recorded in all of the waterbodies studied. Diptera, Trichoptera, Ephemeroptera, and Gastropoda were the major components of the benthic macroinvertebrate communities in the aquatic habitats studied. The biodiversity values of the macroinvertebrate assemblages in the rivers and lakes studied were similar. This likely resulted from the similar number of habitats in both types of waters. Differences in biodiversity among the various waterbodies could be evidence of the moderate, diversified anthropogenic pressure to which they are subjected. The analysis of similarities indicated that in terms of the benthic macroinvertebrate communities, the waterbodies studied formed three groups, which, with just one exception, consisted separately of rivers, ponds, and lakes.

The Great Mazurian Lakes System (GMLS), located in the northeastern part of Poland, is an extremely valuable area in terms of natural environment value, tourism, and local economy. The system is divided into two parts – the northern meso-eutrophic and the southern eutrophic. GMLS are lakes with very high taxonomic diversity of phytoplankton, and cyanobacteria are very often predominant in the species composition and biomass. The presence of cyanobacteria belonging to 14 different families from the orders of Nostocales, Oscillatoriales, Synechococcales, and Chroococcales was recorded throughout the system. The GMLS has undergone significant changes over the recent decades which affected the taxonomic composition and dominant species of cyanobacteria. Particularly the southern part was subject to significant changes, from rapid eutrophication in the 1970s and 1980s, resulting in massive blooms of cyanobacteria, to a significant improvement in water quality in the 1990s and a reduction of cyanobacteria biomass. However, cyanobacteria are the dominant component of phytoplankton up to the present, although there are no dense blooms in recent years. Many of the cyanobacteria taxa in the GMLS can potentially produce toxins. Hepatotoxic microcystins are the most common cyanotoxins in freshwater, and in GMLS they sometimes reached significant concentrations in water. Studies have shown that the main producers of microcystins in GMLS are genera Microcystis and Planktothrix.

The article presents changes in the quantitative and qualitative composition of indicator bacteria in three Polish rivers – Vistula, Oder, and Łyna River – in the last 30 years. The analyzed rivers are situated in the catchment area of the Baltic Sea, and they play important economic, tourist and environmental roles. The sanitary and bacteriological status of these ecosystems was determined based on the counts of total coliform bacteria (TCB), fecal coliform bacteria (FCB), fecal enterococci bacteria (FEB), and Escherichia coli. The study involved a review of the literature and the reports published by Polish inspectorates of environmental protection. Water samples collected from all rivers in urban areas were characterized by the highest TCB, FCB, FEB, and E. coli counts throughout the analyzed period. High contamination levels contributed to epidemiological risks in rivers, in particular in the proximity of discharge points of treated effluents. As a result, most of the analyzed water samples were graded as purity class III and/or as non-class (polluted beyond permissible standards) waters. Since 2003, Polish laws have been harmonized with the provisions of the Water Framework Directive (2000/60/EC), and the range of indicator bacteria was restricted to FEB and E. coli only in water bodies used as sources of water for human consumption and/or for bathing. In Poland, treated wastewater does not have to be disinfected before it is discharged to surface waters. For this reason, contamination with indicator bacteria (TCB, FCB, FEB, and E. coli) continues to be high in water bodies that act as receptacles of wastewater despite considerable reduction of microbiological contamination (97–99%) in treated effluents. The above applies particularly to rivers where contamination spreads. For this reason, the concentration of indicator bacteria should be the main criterion in evaluations of river water purity.

Antimicrobial compounds are widely used in human and veterinary medicine to protect human and animal health, to prevent economic losses, and to help to ensure a safe food supply. After administration, the antibiotics and their transformant products (TPs) may pass through the sewage system and end up in the environment, mainly in the water bodies. Apart from antibiotics and their TPs, antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs), which have been identified as emerging pollutants of concern, enter ecosystems with treated wastewater and livestock manure. In the environment altered by human activity, the occurrence of bacteria resistant to almost all known antibiotics has been confirmed. Despite being universally considered relatively important, land runoff, drainage and seepage are not the sites with the most striking occurrence of the transfer of resistance genes among different species of bacteria. The most significant hot-spots are wastewater treatment plants (WWTPs). Together with treated wastewater which is released from WWTPs, antibiotics, their TPs, ARB, and ARGs can penetrate the surface water, rural groundwater supplies, drinking water, soil, and plants growing in soil irrigated with contaminated water. It creates a direct risk to human and animal health because drugs, ARGs, and ARB transported to the environment can be transferred back to people and animals. The authors of this article aim to familiarize readers with the phenomenon of antibiotic resistance in Poland: its occurrence, ranges of antibiotic concentration, and the number of ARB and ARGs occurring in Polish surface waters as well as main sources of these contaminants.

At present Poland is drained from the Carpathians, located in the south-east, to the Baltic Sea, located in the north-west. In the Pleistocene, however, much of Poland experienced several glaciations, when ice sheets advanced south and retreated. Each one destroyed many river basins and their fish but created periodic connections with the North Sea and Ponto-Caspian catchments. This enabled repeated colonization from fish refugia, which has been discovered using genetic lineage analysis.

The scientific knowledge of rivers and fish in Poland has much increased since World War II, owing to the Scientific Annual of the Polish Angling Association, and then European Community/Union initiatives, which classified rivers into 26 abiotic and 15 fish types. Most rivers belong to barbel and bream zones, while environmental factors affect assemblage composition more than historic ones. Fish in 90% of river systems have been investigated, but in only a few monitored more than twice. Out of 53 native fish and lamprey species, the LC category comprises half, other categories 10% each, while EW, EX and DD ones only solitary species.

Native fishes are threatened by invasions of non-native ones, 24 of which have appeared in Poland since WWII, by pollution, which was severe in the 1960s–1980s but has now much decreased, and by river regulation and impounding, which continuously stress fish populations. The Polish Angling Association administers most inland waters, 0.5 million ha, which are stocked with fish and exploited by 1.5 million anglers.

In this article, we present the most comprehensive and up-to-date assessment of freshwater fish diversity in the lakes of northeastern Poland, and we use these data to characterize patterns of fish diversity and characterize the fisheries. The northeastern region of Poland is home to the country’s largest complex of lakes, with the deepest (Hańcza) and largest (Śniardwy) lakes in Poland. To date, 43 species belonging to 15 families are confirmed to occur in the lakes of northeastern Poland. Among these, the cyprinids are dominant. Most of the fish species noted in this region occur commonly in Poland; however, as many as 27% of the species are classified as highly endangered and are under species conservation. A substantial part of the fish fauna of northeastern Polish lakes is comprised of alien species, of which nine are noted in the region. For centuries, this region was the center of lake fisheries in the southern Baltic Sea basin. Currently, 70 different types of enterprises conduct fisheries in the region, but, in the face of progressing lake eutrophication, changes in catch structure are occurring, and the fisheries yield is decreasing. Common bream (Abramis brama), pike (Esox lucius), roach (Rutilus rutilus), and eel (Anguilla anguilla) are commercially the most important fish species in commercial catches in the lakes of northeastern Poland.

This paper briefly discusses the resources of habitats of importance to the European Community in Poland shaped by water relations. The types of habitat surveyed include water courses and waterbodies, wetlands and riparian vegetation (meadows, forest) and streams and bogs. The study covered 23 habitat types in freshwater habitats and freshwater-dependent habitats occurring in all 849 Special Areas of Conservation in Poland in both biogeographic regions: alpine and continental. The overall conservation value for current habitats is presented, including threats, pressures and activities, as well as their possibilities for restoration.

The study aimed to determine natural communities of invertebrates and ichthyofauna on the background of physiographic and geological conditions and water chemistry and to evaluate the influence of human pressure on these communities on the basis of the results of long-term studies carried out since the 1960s in the Upper Dunajec River and its Tatra tributaries (West Carpathians). Here, for the Dunajec River, we present a pattern of human impact on freshwater fauna communities in mountain streams and rivers with stony bottoms and rapid currents. The Tatra streams (tributaries of the Dunajec River) have mostly retained their natural character. The source of water pollution was mainly from the tourist shelter and tourism centre nearby. Discharge of untreated or partially treated sewage effluent affected invertebrate communities; however, this impact was only observed over a short river section. On the other hand, dam reservoirs completely changed the character of the Dunajec River. In the Czorsztyn Reservoir, communities of macroinvertebrates and fish developed, which are not typical of mountain rivers, replacing previous taxa with those characteristic of slow-flowing waters.

An assessment of the ecological status or potential is based mainly on examination of the aquatic ecosystem functioning regarding organisms that inhabit them. These include phytoplankton, macrophytes and phytobenthos, benthic macroinvertebrates and ichthyofauna. However, hydromorphological and physicochemical elements are also of importance as supporting biological features.

The work presents the problems of revitalization of water reservoirs in Poland. Lakes are subject to the inevitable process of aging, but as a result of anthropopression, the processes of natural eutrophication have been repeatedly accelerated. The consequence of the supply of excess allochtonic matter to water reservoirs, with the passive character of these landscape elements, is their degradation manifested by a sudden deterioration of water quality. A number of methods for the renovation of natural water reservoirs have been developed. Methods involving the removal of excess nutrients outside the ecosystem are the removal of hypolimnion waters, removal of bottom sediments, flushing the lake bowl, and removal of seston, macrophytes, and fish. The second group of methods consists in reducing the amount of nutrients in the matter circulation in the lake. This includes artificial aeration of lakes, inactivation of phosphorus compounds, treatment of bottom sediments, or biomanipulation. Despite such diversification of existing ways of affecting the aquatic environment, both in Poland and in the world, it is rarely possible to obtain really good effects of the restoration measures undertaken. The most common reason for defeats is the failure to take into account the basic assumption of eliminating excess loads of pollutants reaching the lake from the catchment before commencing its reclamation. Poor effects are also caused by insufficient understanding of the functioning of the complicated lake ecosystem and incorrect selection of revitalization techniques according to the environmental conditions of lakes. Properly conducted reclamation requires collecting research results about the lake and its catchment, recognizing the conditions of the eutrophication process, impartial selection of methods, securing funds for all planned operations, and substantive supervision and monitoring which provides the basis for assessing effectiveness and possible adjustments in the project implementation.

This study analyses the dynamics of organic matter and algae pigments in water of urban lakes subjected to various restoration techniques. Most of the lakes were restored with the inactivation method using coagulant PAX 18. One of them was supported with biomanipulation. Assessments of the organic carbon form content (POC, in suspension; DOC, dissolved form) and the chlorophyll and pheophytin concentrations were conducted. The ratios of individual parameters were then evaluated, and the relationships between these indicators were tested. It was found that decreasing primary production and the associated organic matter in a suspended form can improve self-purification processes in restored lakes. The decreasing POC after restoration leads to a reduction in the amount of DOC in the lake and determines the balance of production and decomposition. This improvement may initially be able to reduce the DOC content, mainly due to easily biodegradable compounds. The lower primary production supplies a lower content of hardly biodegradable compounds (when algae decay). After that, the amount of high-molecular-weight DOC can be reduced. The improved self-purification of the lakes was also reflected in a reduced chlorophyll/pheophytin ratio. There was no effective reduction of the organic matter content after the first restoration in polymictic lakes with high loaded biogens and organic matter (DOC) from the catchment.

Using an input-output ecosystem model, it was demonstrated that wetlands of the various stages of anthropogenic transformations typical for the postglacial landscape of N-E Poland vary in nitrogen (N) and phosphorus (P) forms retention. It concerned particularly nitrates (NO₃-N) and phosphates (PO₄-P), the most responsible for eutrophication effect. The calculation of retention effectiveness for studied wetland ecosystems showed that undrained minerotrophic peatland and transition bog retained about 70–85% of total N, including 95% of nitrates, but at the same time, they lost more than 50% of incoming phosphates. Wetlands with a shallow lake or transition bog crossed by a watercourse were considered as typical through-flowing systems with at most a moderate tendency to retained phosphates. Drained peatlands were considered dangerous in exporting N and P forms into recipient lakes and rivers. A directly drained minerotrophic fen lost even 70% of nitrates in the first year after melioration. Formerly drained peatlands can also lose nitrates, but first of all, they lost even 80–100% of total phosphorus input. All drained peatlands examined did not retain or lose total nitrogen and phosphates.

The Tatra Mountains are small range of mountains of alpine character which belong to the Carpathian chain. All components of Tatra nature have a unique character. Tatra lakes are valuable and special environments for hydrobionts. The geological and hydrological attributes as well as water chemistry determining the specificity of those lakes have been described. The uniqueness of life forms present there has been described with regard to epilithic algal, zooplankton, macrozoobenthos and fish communities. The main features determining the structure of Tatra lakes hydrobionts communities are lake altitude, catchment character, water temperature and ice cover period. The influence of anthropogenic activities such as water acidification is also important. Fish introduction to the originally fishless lakes or their natural presence also has significant impact. Vertical distribution of lake organisms is distinctly marked in particular lakes. Based on many parameters, the Tatra lakes can be divided into two groups: of alpine and subalpine character. The water bodies situated on the Polish side of the Tatras are not acidified when compared to those in the Republic of Slovakia. The Tatras and their lakes are the farthest located in Northern Europe centre of endemism and the largest site of high mountain fauna and flora occurrence in Central Europe.