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1

The ecology of Lobelia dortmanna L.I. The plasticity of individuals within a constant depth interval in oligotrophic lakes

100%

Szmeja J.

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1987

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tom 35

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nr 3-4

2

Changes in the aquatic moss Sphagnum denticulatum Brid. population abundance in a softwater lake over a period of three years

100%

Szmeja J.

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tom 79

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nr 2

167-173

EN

Changes in population abundance of submerged Sphagnum denticulatum Brid. were studied in an acidic and oligotrophic lake in NW Poland over three years. Individuals were counted in a moss carpet at a depth of 2.5 m on 4 experimental plots, 1 × 1 m each, every 30 days for 36 months using the SCUBA method. PAR intensity was seasonally variable (in winter higher than in summer). Changes in water pH, conductivity, HCO3- concentration, hydration and sediment pH were statistically insignificant (p > 0.05). In the summer of the second study year the moss carpet disappeared almost completely due to a massive bloom of filamentous green algae. Periods of growth, regression and regeneration were observed in the population. The stabilisation of population size took 24 months and followed the pattern: slight fluctuations, then rapid growth and repetition of slight fluctuations. The first stage lasted nine, the second four and the third nine months. These stages took place irrespective of seasons, temperature or PAR intensity. Each rapid increase in abundance lasted about 30 days, at PAR intensity >20% and water temperature ranging from 11 to 16oC (in winter, spring or autumn). The regression stage brought about by the algal bloom started in the second year (in summer) and lasted six months (until the end of January in the third year). The population regeneration began in winter (in February, water temperature 3.0oC, PAR about 20%, ice cover 0.15 m) and finished with the end of spring. The population of S. denticulatum shows a repetitive pattern of abundance variations, which is seriously disturbed in summer, especially after a warm spring, by a massive bloom of filamentous green algae.

3

The ecology of Lobelia dortmanna L.III. The plasticity of individuals along a gradient of increasing depth in oligothropic lakes

100%

Szmeja J.

|

1987

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tom 35

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nr 3-4

4

Evolution and conservation of lobelia lakes in Poland

100%

Szmeja J.

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nr 1

5

The disintegration of populations of underwater plants in soft water lakes enriched with acidic organic matter

63%

Szmeja J. , Bociag K.

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nr 2

EN

The characteristics of habitats, individuals and populations of four submerged macrophytes, Lobelia dortmanna L., Isoetes lacustris L., Sphagnum denticulatum Brid. and Fontinalis antipyretica Hedw., were studied in 12 soft water oligohumic lakes which had no inflow of allochtonic DOM and the DOC concentration in the water was <4.0 mg C dm-3 and 13 humic lakes enriched with allochthonous dissolved organic matter (DOM) from drained peat bogs and ranging in DOC water concentration from 4.1 to 44.0 mg C dm-3. The analyses of population disintegration were conducted basing on characteristics of individuals (size, habitat, fertility) and populations (aggregation density index, settlement index of the population area). The settlement index of the population area for Lobelia, Fontinalis, Isoetes, Sphagnum decreased from 8.4 to 6.2 g d.w. m-2, 4.6 to 0.01 g d.w. m-2, 85.4 to <0.001 g d.w. m-2 and 39.3 to 7.2 g d.w. m-2, respectively. Similar trends were observed in aggregation density. The general pattern of the disintegration of populations of these species was always similar. It was independent of the source macrophytes drew resources from or their susceptibility to environmental changes. Individuals began to be eliminated from the deep and central parts of the population area. The remainder of the populations, which persist in the shallowest, best-illuminated part of the area, are themselves endangered by disturbances caused by wavy motion. The only populations of submerged macrophytes which can survive in polyhumic lakes under such conditions are those which are resistant to disturbances common in the shallow littoral (Lobelia dortmanna, Fontinalis antipyretica).

6

Effect of pH, dissolved organic carbon and total phosphorus concentrations on selected life history traits of Luronium natans [L.] Raf.

63%

Bazydlo E. , Szmeja J.

Polish Journal of Ecology

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2004

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tom 52

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nr 2

EN

A hypothesis has been put forward that low pH or high concentration of total phosphorus (TP) and dissolved organic carbon (DOC) in the lake water are the factors responsible for observed extinction of the population of Luronium natans (L.) Raf., protected macrophyte species from the group of isoetids. A study was performed on 525 generative individuals collected from 21 lakes in Pomeranian Lakeland (NW Poland) and a correlation between the biometric characteristics and environmental conditions in the lakes was tested. The following life history traits have been analysed: size of individuals, their fecundity and allocation of biomass. The greatest and most fecund individuals grow in the lake water of pH 6.1–7.0, poor in TP (10.1–20.0 µg dm⁻³) and DOC (3.5–6.0 mg C dm⁻³). The allocation of biomass of the individuals growing in the optimum conditions is as follows 46–54% in the leaves, 22–31% in the roots and 20–27% in the rhizome. In the lakes with water of pH < 5.0 or of TP > 20.1 µg dm⁻³ and DOC > 6 mg C dm³, a statistically significant decrease in the size of the individuals and unfavourable changes in the biomass allocation are found. The main environmental factor responsible for dying out of local populations of Luronium natans is a decrease of pH below < 5.0.

7

Changes in the vegetation of softwater lakes under the influence of humic substances

63%

Bociag K. , Szmeja J.

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nr 4

8

Roslinnosc projektowanego nadmorskiego ogrodu botanicznego w Trojmiescie

51%

Faltynowicz W. , Picinska-Faltynowicz J. , Szmeja J.

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nr 06

9

Diagnoza jezior lobeliowych w zachodniej czesci Pojezierza Pomorskiego

51%

Banas K. , Bociag K. , Szmeja J.

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tom 46

83-105

10

Effect of light competition with filamentous algae on the population dynamics and development of the moss species Warnstorfia exannulata in a softwater lake

51%

Szmeja J. , Bociąg K. , Merdalski M.

Polish Journal of Ecology

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2010

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tom Vol. 58, nr 2

221-230

EN

The effect of a massive bloom of filamentous algae on the long-term abundance dynamics of the moss Warnstorfia exannulata (B., S. & G.) Loeske was studied in an acidic lowproductivity lake in NW Poland. Individuals were counted on 4 experimental plots, 1 x 1 m each, at a depth of 2.5 m. The studies were conducted for 36 months, every 30 days, by SCUBA diving. Over the three years the seasonal changes in water pH, conductivity, HCO3 - concentration, sediment hydration and pH were not statistically significant (P> 0.05), and light intensity was higher in winter than in summer. Over the three years 4 consecutive stages of population development were observed: regeneration, stabilisation of abundance (fluctuations), regression and repeated regeneration. These stages appeared and lasted at different temperatures and light intensity. The greatest monthly increase in abundance took place in summer and lasted until the beginning of autumn under conditions of high temperature and relatively low light intensity. Long-term abundance variations were strongly correlated with the appearance of filamentous algae, less strongly with the dynamics of the dominant species (Sphagnum denticulatum), and the least with water temperature, light intensity, water and sediment pH, conductivity and HCO3 - concentration. As a result of a massive bloom of these algae, light intensity decreased in the water, Warnstorfia shed its leaves, and then the entire population disappeared. In winter that year it began to regenerate from vegetative propagules (leafless shoots), which were the remains of individuals growing before the filamentous algae appeared. In softwater lakes such massive algal blooms are a common phenomenon which limits light transmission to the substrate and as a result leads to changes in the submerged vegetation structure, especially that of bryophytes.

11

Effect of light competition with filamentous algae on the population dynamics and development of the moss species Warnstorfia exannulata in a softwater lake

51%

Szmeja J. , Bociag K. , Mierdalski M.

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nr 2

EN

The effect of a massive bloom of filamentous algae on the long-term abundance dynamics of the moss Warnstorfia exannulata (B., S. & G.) Loeske was studied in an acidic lowproductivity lake in NW Poland. Individuals were counted on 4 experimental plots, 1 × 1 m each, at a depth of 2.5 m. The studies were conducted for 36 months, every 30 days, by SCUBA diving. Over the three years the seasonal changes in water pH, conductivity, HCO₃⁻ concentration, sediment hydration and pH were not statistically significant (P> 0.05), and light intensity was higher in winter than in summer. Over the three years 4 consecutive stages of population development were observed: regeneration, stabilisation of abundance (fluctuations), regression and repeated regeneration. These stages appeared and lasted at different temperatures and light intensity. The greatest monthly increase in abundance took place in summer and lasted until the beginning of autumn under conditions of high temperature and relatively low light intensity. Long-term abundance variations were strongly correlated with the appearance of filamentous algae, less strongly with the dynamics of the dominant species (Sphagnum denticulatum), and the least with water temperature, light intensity, water and sediment pH, conductivity and HCO₃⁻ concentration. As a result of a massive bloom of these algae, light intensity decreased in the water, Warnstorfia shed its leaves, and then the entire population disappeared. In winter that year it began to regenerate from vegetative propagules (leafless shoots), which were the remains of individuals growing before the filamentous algae appeared. In softwater lakes such massive algal blooms are a common phenomenon which limits light transmission to the substrate and as a result leads to changes in the submerged vegetation structure, especially that of bryophytes.

12

Relationship between the shore vegetation and the evolution of oligotrophic lakes

51%

Szmeja J. , Markowski R. , Gos K. , Olszak I.

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nr 2