76
M. Rz˛ etała
presence of 1 kg of phosphorus in water may lead to the production of around 1 tonne
of fresh algae. On the other hand, the concentration of phosphorus at which so-called
algal blooms may appear (as a result of excessive phytoplankton growth) is around
20–30 μg P/dm
3 for lowland reservoirs impounded by dams [33]. In oligotrophic and
oligomezotrophic water bodies without anthropogenic pollution loads, phosphorus
concentrations do not exceed around a dozen μg/dm
3 [33]. Threshold values of basic
water indices above which the eutrophication process occurs have been defined at
the following levels for lentic waters: above 0.1 mg P/dm
3 for total phosphorus,
above 1.5 mg N/dm
3 for total nitrogen, above 25 μg/dm
3 for chlorophyll α and
below 2 metres for water transparency. The development of this process is evidenced
by long-term algal blooms, which in lakes are often caused by cyanobacteria, the
growth of periphyton algae on a massive scale, the disappearance of oxygen from the
hypolimnion (with possible hydrogen sulphide secretion), and finally the reduction
in the diversity and abundance of macrophytes, invertebrate fauna and fish. Most
of these indices refer directly or indirectly to the water trophic classifications used
worldwide, among which Organization for Economic Cooperation and Development
guidelines are a common standard [34].
The content of chlorophyll α is the parameter that best expresses the volume
of primary production [35]; in the case of most water bodies, this figure indicates
that the water is being enriched with nutrients and intense phytoplankton growth
is taking place. In some water bodies burdened with agricultural pollutant runoffs,
chlorophyll α reaches average annual concentrations which are only slightly higher
than the threshold values, but maximum concentrations have exceeded these values
many times. Therefore, it is difficult to find water bodies in Poland which would
be similar in terms of their chlorophyll α concentrations to reservoirs impounded
by dams that are located in quasi-natural environments, e.g. the Wisła Czarne (1–
1.5 μg/dm
3 ) and Wapienica (ca. 1 μg/dm
3 ) Reservoirs in the Beskidy Mountains
[18].
Concentrations of phosphorus and nitrogen compounds in water bodies in Poland
vary greatly—from levels considered natural to those which indicate comprehensive
degradation of the aquatic environment; there are also a number of water bodies which
represent intermediate ranges of nutrient concentrations [18]. In general, water bodies
in urban-industrial catchments exhibit processes typical of polytrophy and hypertrophy (e.g. the Dzier˙ zno Du˙ ze Reservoir) [18, 36, 37], while in water bodies with
catchment areas used for agricultural purposes, the eutrophication problem stems
mainly from their pollution with nitrogen compounds from agricultural sources, e.g.
the Kozłowa Góra Reservoir [38], Sulejów Reservoir [39].
An additional criterion reflecting the eutrophication of water bodies in Poland is
water transparency. The most transparent water bodies were found in quasi-natural
catchments which were insulated from the inflow of pollutants, and the lowest
transparency was found in strongly eutrophicated waters in catchments used for
agricultural purposes or in urban-industrial catchments.
Compared to the general trophic status of lentic waters, the hypertrophy and
polytrophy of the Dzier˙ zno Du˙ ze Reservoir stand out, which is the effect of supply
of pollutants from the Kłodnica River [37]. Thus, the environment in which fish
M. Rz˛ etała
presence of 1 kg of phosphorus in water may lead to the production of around 1 tonne
of fresh algae. On the other hand, the concentration of phosphorus at which so-called
algal blooms may appear (as a result of excessive phytoplankton growth) is around
20–30 μg P/dm
3 for lowland reservoirs impounded by dams [33]. In oligotrophic and
oligomezotrophic water bodies without anthropogenic pollution loads, phosphorus
concentrations do not exceed around a dozen μg/dm
3 [33]. Threshold values of basic
water indices above which the eutrophication process occurs have been defined at
the following levels for lentic waters: above 0.1 mg P/dm
3 for total phosphorus,
above 1.5 mg N/dm
3 for total nitrogen, above 25 μg/dm
3 for chlorophyll α and
below 2 metres for water transparency. The development of this process is evidenced
by long-term algal blooms, which in lakes are often caused by cyanobacteria, the
growth of periphyton algae on a massive scale, the disappearance of oxygen from the
hypolimnion (with possible hydrogen sulphide secretion), and finally the reduction
in the diversity and abundance of macrophytes, invertebrate fauna and fish. Most
of these indices refer directly or indirectly to the water trophic classifications used
worldwide, among which Organization for Economic Cooperation and Development
guidelines are a common standard [34].
The content of chlorophyll α is the parameter that best expresses the volume
of primary production [35]; in the case of most water bodies, this figure indicates
that the water is being enriched with nutrients and intense phytoplankton growth
is taking place. In some water bodies burdened with agricultural pollutant runoffs,
chlorophyll α reaches average annual concentrations which are only slightly higher
than the threshold values, but maximum concentrations have exceeded these values
many times. Therefore, it is difficult to find water bodies in Poland which would
be similar in terms of their chlorophyll α concentrations to reservoirs impounded
by dams that are located in quasi-natural environments, e.g. the Wisła Czarne (1–
1.5 μg/dm
3 ) and Wapienica (ca. 1 μg/dm
3 ) Reservoirs in the Beskidy Mountains
[18].
Concentrations of phosphorus and nitrogen compounds in water bodies in Poland
vary greatly—from levels considered natural to those which indicate comprehensive
degradation of the aquatic environment; there are also a number of water bodies which
represent intermediate ranges of nutrient concentrations [18]. In general, water bodies
in urban-industrial catchments exhibit processes typical of polytrophy and hypertrophy (e.g. the Dzier˙ zno Du˙ ze Reservoir) [18, 36, 37], while in water bodies with
catchment areas used for agricultural purposes, the eutrophication problem stems
mainly from their pollution with nitrogen compounds from agricultural sources, e.g.
the Kozłowa Góra Reservoir [38], Sulejów Reservoir [39].
An additional criterion reflecting the eutrophication of water bodies in Poland is
water transparency. The most transparent water bodies were found in quasi-natural
catchments which were insulated from the inflow of pollutants, and the lowest
transparency was found in strongly eutrophicated waters in catchments used for
agricultural purposes or in urban-industrial catchments.
Compared to the general trophic status of lentic waters, the hypertrophy and
polytrophy of the Dzier˙ zno Du˙ ze Reservoir stand out, which is the effect of supply
of pollutants from the Kłodnica River [37]. Thus, the environment in which fish