The Konin Lakes are a group of lakes forming a long navigable channel in central Poland. The lakes include Pątnowskie Lake, Mikorzyńskie Lake, Gosławskie Lake, Licheńskie Lake and Ślesińskie Lake, connecting the River Warta and Lake Gopło and linked to the Warta-Goplo Canal. The lakes are of particular interest because they receive the water outlets from two power stations and the temperature of the water is significantly raised, supporting a different flora and fauna to other lakes in the region. Water for the two power stations is drawn primarily from Lake Pątnowskie, and discharged via canals to Lake Licheńskie, with other outlets flowing into the other lakes. The cooling scheme varies with the time of year, with Licheńskie, Ślesińskie and Mikorzyńskie being included in June but excluded in October. The total area of the lakes is between , and the greatest depth is . Lake Licheńskie is shallow and shows the greatest temperature variation, reaching a maximum of in mid summer while the deeper Lake Ślesińskie reached .

Flora and fauna

In the mid 1990s,

eel grass Eelgrass is a common name for several plants and may refer to: * ''Zostera'', marine eelgrass * ''Vallisneria ''Vallisneria'' (named in honor of Antonio Vallisneri) is a genus of freshwater aquatic plant, commonly called eelgrass, tape grass or ...

(''Vallisneria spiralis''), a non-native species, made its appearance in three of the lakes and a decade later was present in the littoral regions of four lakes, growing so vigorously as to exclude other vegetation in many shallow parts. The changes in temperature and in vegetation altered the balance of micro-organisms present, new

rotifer The rotifers (, from Latin 'wheel' and 'bearing'), sometimes called wheel animals or wheel animalcules, make up a phylum (Rotifera ) of microscopic and near-microscopic Coelom#Pseudocoelomates, pseudocoelomate animals. They were first describ ...

species appeared and competed with existing species, native populations often having little defence and being crowded out. Larger organisms also appeared; non-native species now living and breeding in the lakes include three species of

bryozoa Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic animal, aquatic invertebrate animals, nearly all living in sedentary Colony (biology), colonies. Typically about long, they have a spe ...

n, three

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

s, seven

molluscs Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

and at least six species of fish. The hotter water encourages

eutrophication Eutrophication is a general term describing a process in which nutrients accumulate in a body of water, resulting in an increased growth of organisms that may deplete the oxygen in the water; ie. the process of too many plants growing on the s ...

and alters the proportions of fish species present;

common bream The common bream (''Abramis brama''), also known as the freshwater bream, bream, bronze bream, carp bream or sweaty bream, is a European species of freshwater fish in the family Leuciscidae. It is now considered to be the monotypic, only speci ...

and

white bream ''Blicca'' is a monospecific genus of freshwater ray-finned fish belonging to the family Leuciscidae. The only species in the genus is ''Blicca bjoerkna'', the white bream or silver bream. This species is found in Europe and Western Asia. Distr ...

are able to thrive while populations of

predatory fish Predatory fish are hypercarnivorous fish that actively prey upon other fish or aquatic animals, with examples including shark, billfish, barracuda, alligator gar, tuna, dolphinfish, walleye, perch and salmon. Some omnivorous fish, such as t ...

diminish. When the discharges from the power station into Lakes Licheńskie, Ślesińskie and Mikorzyńskie cease in the autumn,

common roach The roach, or rutilus roach (''Rutilus rutilus''), also known as the common roach, is a fresh- and brackish-water fish of the family Cyprinidae, native to most of Europe and western Asia. Fish called roach can be any species of the genera ''Rut ...

numbers diminish from 28–56% of the total fish stock in June to 1–2% in October. It is probable that the roaches migrate to the warmer lakes nearer the power stations in autumn. A number of animals more familiar from marine or brackish environments are also present in the Konin Lakes; these include the flatworms '' Bresslauilla relicta'', '' Otomesostoma auditivum'' and '' Macrostomum rostratum''.

References

{{portalbar, Lakes Konin County Lakes of Poland