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1

Comparing effect of phytoplankton and a charophyte on calcite precipitation in lake water: experimental approach

Kufel L., Rymuza K.

Polish Journal of Ecology

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2014

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Vol. 62, nr 3

431--439

EN

Primary producers are able to strongly affect calcium budget in hardwater lakes. The relative contribution of phytoplankton and charophytes to water decalcification (by precipitation of calcium carbonate) is, however, unclear. In this study we checked the effect of natural phytoplankton community and a charophyte (Nitellopsis obtusa) on the decline of calcium concentration in experimental outdoor conditions. The experiment was carried out in original lake water and two variants of enrichment with inorganic nitrogen and phosphorus to test the changing efficiency in decalcification by both primary producers. At low nutrient concentrations, N. obtusa was responsible for calcium decline in original lake water by 12 mg Ca+2 dm-3 during 20 days of experiment. In these conditions the effect of phytoplankton was negligible. In lake water enriched with nutrients, the exponential growth of phytoplankton led to the decrease of calcium concentration from initial 35 mg Ca+2 dm-3 to 9 mg Ca+2 dm-3 in the same time period. The maximum effect of N. obtusa was the same as in original lake water but manifested itself earlier to decline in the end of experiment. Supersaturation of water with calcium carbonate was always more than threefold and saturation index reached 27 in mixed cultures of phytoplankton and N. obtusa in lake water enriched with nutrients. In this context we hypothesise on a possible role of charophytes as nucleation sites necessary for calcite precipitation. Based on our own and literature data we also discuss expected immobilisation of phosphate incorporated in calcite precipitated by the growth of phytoplankton and N. obtusa.

2

Growth rate of duckweeds (Lemnaceae) in relation to the internal and ambient nutrient concentrations - testing the Droop and Monod models

Kufel L., Strzałek M., Wysokińska U., Biardzka E., Oknińska S., Ryś K.

Polish Journal of Ecology

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2012

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Vol. 60, nr 2

241-249

EN

The Monod model describes the relationship between growth rate and ambient nutrient concentration, the Droop model focuses on internal nutrient resources as the driving factor. Both were applied mainly to explain phytoplankton dynamics in lakes or in experimental cultures. Our test plants were two species of duckweeds - Lemna minor L. and Spirodela polyrhiza (L.) Schleiden sampled from 18 natural stands situated in 6 different water bodies. Plants were grown outdoor in original lake water or in mineral media of varying N and P concentrations (0-21 mg N-NO3 L[^-1] and 0-1853 [mu]g P-PO4 L[^-1] for L.minor and 0-4.2 mg N-NO3 L[^-1] and 0-371 [mu]g P-PO4 L[^-1] for S. polyrhiza). Moreover, we analysed concentrations of mineral forms of N and P in lake water and tissue nutrient concentrations in plants. Tissue N of both plants was significantly correlated with ambient inorganic nitrogen sources, no such relationship was observed for tissue P. The growth rate of both plants measured under experimental outdoor conditions was better explained by tissue N and P variability (the Droop model) than by the external nutrient availability (the Monod model). The latter also failed to fit the growth rate of both plants in artificial mineral media with a decreasing gradient of N and P concentrations. The plants grew at the expense of internal N and P resources which remarkably declined during 9-day long experiments. Calculated minimum tissue contents (11.19 [plus or minus] 1.11 mg N g[^-1] and 0.97 [plus or minus] 0.07 mg P g[^-1] in L. minor and 6.10 [plus or minus] 1.85 mg N and 1.25 [plus or minus] 0.37 mg P g[^-1] in S. polyrhiza) show that the latter species would be a superior competitor under N limiting conditions and the former - under P limitation. We confront obtained results with literature data on N uptake kinetics and postulate that the luxury consumption of nutrients and plant growth dependent mainly on internal N and P resources might be an adaptation of duckweeds to varying habitat conditions typical of astatic water bodies.

3

Are fishponds really a trap for nutrients? - a critical comment on some papers presenting such a view

Kufel L.

Journal of Water and Land Development

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2012

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no. 17 [VII-XII]

39-44

EN

There is still a controversy about the environmental impact of fishponds, especially on their ability to retain nutrients. This paper presents some basic rules of nutrient cycling in running and stagnant waters and the biotic and abiotic transformation of nutrients delivered to dam reservoirs and fishponds. Based on these common properties of eutrophic stagnant waters, some critical remarks are presented on papers that claim to prove the capacity of fishponds to retain nutrients (mainly nitrogen) during fish production and after pond drainage. Finally, some ways of reducing negative environmental impacts of fishpond effluents are described as an indirect evidence that such impacts really pose a threat to water quality.

PL

Nadal nierozstrzygnięty pozostaje spór o środowiskowe oddziaływanie stawów rybnych, szczególnie w odniesieniu do ich zdolności zatrzymywania pierwiastków biogennych. W artykule przedstawiono podstawowe zasady obiegu pierwiastków biogennych w wodach płynących i stojących oraz biotyczne i abiotyczne przemiany, którym podlegają te pierwiastki w wodach zbiorników zaporowych czy stawów rybnych. Odwołując się do tych zasad, przedstawiono uwagi krytyczne wobec pewnych badań, których autorzy dowodzą retencyjnych zdolności stawów rybnych, zwłaszcza zdolności do retencji azotu. Jako pośredni dowód potencjalnych zagrożeń, w końcowej części artykułu przedstawiono różne zabiegi i sposoby, które są podejmowane, by te zagrożenia minimalizować.

4

Constitutive allelochemicals from Stratiotes aloides L. affect both biomass and community structure of phytoplankton

Kufel L.

Polish Journal of Ecology

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2007

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Vol. 55, nr 2

387-393

EN

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 iduced by competition between macrophyte and algae.

5

The effect of lake water characteristics on decomposition of aquatic macrophytes

Kufel L., Kufel I., Królikowska J.

Polish Journal of Ecology

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2004

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Vol. 52, nr 3

261-273

EN

In situ decomposition of the hornwort (Ceratophyllum demersum L.), the buckbean (Menyanthes trifoliata L.) and leaf blades of the yellow water lily (Nuphar lutea L.) was studied with the litter bag method in three small mid-forest lakes of different pH and nutrient content. Time course of decomposition and of nutrient release from decomposing plant material was best fitted with a logarithm approximation and not by usually used exponential fit. pH of lake waters strongly affected decomposition rates of C. demersum and M. trifoliata. No effect of nutrient concentrations in lake water or in plant tissues on decomposition was noted for any of the analysed plants. Organic carbon deficit is speculated as a possible reason for the observed pH effect on decomposition rates. Modification of particulate and soluble N:P ratios are underlined as a consequence of different N and P release from decomposing plant material.

6

Does biotic patchiness in a lake conform to chemical heterogeneity?

Kufel I., Kufel L.

Polish Journal of Ecology

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2001

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Vol. 49, nr 4

427-430

EN

Analyses of lake water taken in discrete sites along a c. 2 km transect from a 1 m depth in a eutrophic Lake Miko?ajskie revealed a uniform horizontal distribution of temperature and oxygen concentrations. Conductivity, soluble reactive phosphorus and particularly chlorophyll concentrations showed, however a marked variability along the transect. Significant correlation between pH and conductivity suggest that a local photosynthetically induced calcite precipitation may be responsible for the observed horizontal variability of these parameters. Biotic response (inferred from chlorophyll concentrations) was not coupled with chemical differences. Different temporal scales of chemical processes and phytoplankton growth are assumed to explain this discrepancy.

7

Spatial variability and long-term changes of the trophic parameters in the Great Masurian Lakes (Poland)

Kufel I., Kufel L.

Polish Journal of Ecology

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1999

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Vol. 47, no 3

323-333

EN

Hydrologic division of the Great Masurian Lakes (North-eastern Poland) into the northen and southern drainage basin was found to be reflected in different trophic status of lakes. Chlorophyll (but not nutrient) concentrations in the northern part of the system were significantly lower than those in lakes of the southern part. It has been shown that tunnel-valley lakes (numerous in the southern watershed) appear to be more eutrophied in terms of chlorophyll abundance than morainic stratified lakes. Hypolimnetic enrichment and internal loading were probably responsible for the lack of in-lake phosphorus and chlorophyll decline in spite of the evident decrease of the external nutrient loading which had taken place between 1985 and 1996. Such a positive response was observed, however, in the case of nitrogen. Only in a hypertrophic Lake Niegocin some symptoms of recovery were noted after reduction of external point source pollution.

8

Chlorophyll - nutrients - Secchi disc relationships in the Great Mazurian Lakes (North-Eastern Poland)

Kufel L.

Polish Journal of Ecology

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1998

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Vol. 46, no 3

327-337

EN

The relationships between SD, chlorophyll, total phosphorus and total nitrogen were analysed basing on data from 25 sites in 21 Great Mazurian Lakes collocted during 12 years. Best fit for the data were reached when piecewise linear regression was used to approximate the relationship between chlorophyll and nutrient concentrations. The regression line divided the whole data set into two regions: lower, mesotrophic (chlorophyll < 20 mg m^-3) where the response of chlorophyll to N and P was insignificant and higher, eutrophic (chlorophyll > 20 mg m^-3) within which chlorophyll yield was proportional to nutrient increments. Except for trophic type, the relationship between chlorophyll and nutrients was affected by mixing type of lakes. No significant relationships between chlorophyll, nutrient concentrations and Secchi disc visibility were found in the shallow, polymictic lakes. Possible explanations for the observed effects including resuspension and grazing pressure on algae are proposed.