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Anthropogenic changes in properties of the water and spatial structure of the vegetation of the lobelia lake Lake Modre in the Bytów Lakeland

Kraska M., Klimaszyk P., Piotrowicz R.

Oceanological and Hydrobiological Studies

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2013

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Vol. 42, No. 3

302--313

EN

Lake Modre is a lobelia lake. Numerous typical plant species occur here, including Lobelia dortmanna, Littorella uniflora, Isoetes lacustris, and Sphagnum denticulatum. They develop the following associations: Lobelietum dortmannae (Oswald 1923) Tx. ap. Dierss. 1972, Isoetetum lacustris Szańkowski et Kłosowski 1996 n.n., and a community with Sphagnum denticulatum Brid. In 1991, the water of the lake was characterised by low concentrations of nutrients and calcium, acid reaction (pH<5), and Secchi depth visibility of 12 m. Following fry stocking in the lake in 1993 fish farming took place until approximately 1996. During this period the water quality in the lake changed radically in physiochemical terms. Water transparency decreased. Thermal and oxygen stratification developed, with oxygen deficits in the near-bottom layer. Concentrations of nutrient elements increased. Drastic long-term changes were observed in the spatial and quantitative features of the lake vegetation. These particularly related to the instability of Lobelia dortmanna, and the diminishment of the phytocoenosis of Lobelietum dortmannae. Consequently, the phytocoenosis occurred only in the shallowest part of the phytolittoral. L. uniflora expanded, increasing its occurrence annually. Significant fluctuations in quantities of S. denticulatum occurred, correlated with changes in physiochemical water parameters, but shifted in time.

2

The disappearance of stonewort populations in lobelia lakes of the Kashubian Lakeland (NW Poland)

Bociąg K., Rekowska E., Banaś K.

Oceanological and Hydrobiological Studies

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2011

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Vol. 40, No.2

30-36

EN

The subject of this work is a comparative analysis of stonewort populations in 5 lobelia lakes of the Kashubian Lakeland based on literature data from the mid-1970s and the authors' own studies from 2006. In the 1970s 15 sites of 7 stonewort species: Chara delicatula, C. fragilis, C. tomentosa, C. rudis, Nitella flexilis, N. opaca and N. mucronata were recorded in the lakes under study. The populations of C. delicatula and N. flexilis occupied the area from 0.3 to 6 m deep and were characterized by 20% cover on average. Thirty years later, in 2006, the presence of only 6 out of 15 stands was confirmed: 3 of C. delicatula and 3 of N. flexilis. Thus, a total of 9 stands (60%) and 5 species (71%) had disappeared completely. The majority of the preserved populations survived in a vestigial form. Population areas of C. delicatula reached a depth of 2 m and their cover did not exceed 5%. Populations of N. flexilis occupied the littoral up to a depth of 7 m and had 10% cover. The disappearance of stoneworts was probably caused by both anthropogenic factors and natural processes.

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Occurrence of Some Heavy Metals in Bottom Sediments of Lobelia Lakes

Mielnik L., Czekała J., Piotrowicz R., Klimaszyk P.

Ecological Chemistry and Engineering. A

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2011

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Vol. 18, nr 9-10

1293-1300

EN

The paper presents the occurrence of zinc (Zn), copper (Cu) and manganese (Mn) in bottom sediments of selected Lobelia lakes which are specific and unique aquatic reservoirs. The lake sediments were sampled in summer stagnation in the surface layer at two stands in each lake: in littoral zone and in profundal zone at maximum depth of the lake. Results of the investigations show that Zn, Cu and Mn contents in the investigated bottom sediments were low and ranged within geochemical background limits or slightly exceeded them. Presence of the metals in the sediments was spatially differential. Zn, Cu and Mn contents were significantly higher in most cases in the profundal zone of each investigated lake than they were in the litoral zone. Another factor which significantly differs the heavy metals content was level of thermal stratification.

PL

W pracy przedstawiono występowanie cynku, miedzi i manganu w osadach dennych wybranych jezior lobeliowych, stanowiących specyficzną grupę jezior. Osady jezior pobierano w okresie stagnacji letniej z warstwy powierzchniowej, z dwóch miejsc: strefy brzegowej i w miejscu maksymalnej głębokości zbiornika. Wyniki badań zawartości cynku, miedzi i manganu w osadach badanych jezior wskazują, że stężenia tych pierwiastków były niskie i mieściły się w granicach tła geochemicznego lub nieznacznie je przekraczały. Obecność analizowanych metali w osadach była zróżnicowana przestrzennie. W większości przypadków zawartość cynku, miedzi i manganu była istotnie większa w osadach deponowanych w miejscu maksymalnej głębokości każdego jeziora w porównaniu z zawartością tych metali w osadach strefy litoralu. Czynnikiem, który istotnie różnicował zawartość analizowanych metali, była wykształcona w pełni stratyfikacja termiczna wód lub jej brak.

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Endopsammic algal communities from shallow littoral sediments of Lobelia lake (the Pomeranian Lakeland, Northern Poland)

Picińska-Fałtynowicz J.

Oceanological Studies

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1998

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Vol. 27, No. 2

51-67

EN

Endopsammic algal communities from shallow littoral sediments in a subeutrophic Lobelia lake are presented. The flora in the studied lake consisted of 492 taxa. During the two years of study, the density of algae fluctuated between 0.65x103 and 23.24x103 individuals in 1 cm3 of sand and resulted mainly from growth of cyanobacteria, green algae and diatoms. The poorest communities occurred in spring, the most abundant in summer and autumn. In 1985, cyanophytes dominated (up to 92%) and Aphanotece microscopica in particular; the latter species grew in masses, particularly in summer and constituted more than 50% to 64% of the total quantity. In the next year, greater abundance of green algae, diatoms and desmids was noted, probably owing to the higher concentration of nutrients in interstitial water. The most suitable conditions for algal growth created sediments of flat bottom stabilized by isoetids. Mass development of certain cyanobacteria species resulted from medium trophy of the lake.