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1
Content available remote 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
Content available remote Vertical distribution of benthic macroinvertebrates in a meromictic lake (Lake Czarne, Drawieński National Park)
Klimaszyk P., Heymann D.
Oceanological and Hydrobiological Studies
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2010
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Vol. 39, No.4
99-106
EN
Investigations of the distribution of benthic macroinvertebrates in Lake Czarne were conducted in fall 2005 and spring 2006. Samples were taken in three transects (at a depth of 0.5 m and at 5 m intervals). It was noted that macrobenthos only inhabit depths to 10 m. Laminar sediments from 15 m to 29 m indicate that macrobenthos never inhabit the deepest part of the lake in spite of temporary oxygen abundance (between 15 and 20 m during the winter and spring mixing periods). The largest diversity and biomass of macrozoobenthos was observed in the littoral zone at a depth of 0.5 m. At a depth of 5 m in the characean stands and at a depth of 10 m the number and biomass of benthic macroinvertebrates were significantly smaller. The reason for the decrease of benthos density seems to be gradual oxygen depletion.
3
Content available remote Adaptations of pupae of Chironomidae (Insecta: Diptera) to oxygen-poor habitats
Marziali Laura, Lencioni Valeria, Rossaro Bruno
Polish Journal of Ecology
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2006
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Vol. 54, nr 4
687-693
EN
Morphological, behavioural and physiological adaptations of chironomids pupae to oxygen-poor habitats, such as the profundal zone of lakes, are discussed. Lentic and oxyregulator species possess developed respiratory organs (thoracic horns) and an extensive anal fringe to perform respiratory movements, whereas in rheophilic and oxy-conformer species these structures are reduced or absent. This led to the hypothesis that the number of thoracic horn branches, the number of anal macrosetae and the body size could consititute a measure of a species' oxygen requirements. These characters were analyzed in 12 species groups collected in 39 Italian lakes. Numbers were correlated to the optimum value of oxygen level, total phosphorus concentration and transparency calculated for each taxon. Taxa with plumose thoracic horns, extensive anal fringe and large body size (Chironomus) inhabited habitats poorer in oxygen than those inhabited by taxa with less extensive respiratory surface and fringe and small body size (Paratendipes, Polypedilum, Microtendipes). Stictochironomus was less tolerant than expected. Further studies are needed into the physiological adaptations of chironomid pupae.
4
Content available remote Oxygen depletion during illumination of photosensitizers in aqueous solutions
Valaneiunaite J., Zerebcova J., Streckyte G., Bagdonas S., Rotomskis R.
Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna
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2006
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Vol. 12, nr 4
281-286
EN
Background: Most of the photosensitizers used in the photodynamic therapy are degraded during light illumination. This process is accompanied by depletion of oxygen. Objectives: The spectroscopic studies on photobleaching and oxygen Consumption of three hydrophilic second-generation photosensitizers were performed. Material and Methods: Aluminium phthalocyanine tetrasulphonate (AlPcS4), mesotetra(sulphonatophenyl)porphine (TPPS4) and chlorin e6 (Ce6) were examined in pure aqueous solutions and in the presence of bovine serum albumin (BSA). A singlet oxygen quencher: sodium azide (NaNs) was used for comparative purposes. Results: Under laser irradiation of pure solutions, no photobleaching was noticed for TPPS4 and it was negligible for AlPcS4. It was stated that Ce6 photodegraded most rapidly from all of three sensitizers. During irradiation, no oxygen consumption was recorded for AlPc-S4 and TPPS4 except for solutions of Ce6 (6,7x10"M). The interaction with BSA significantly increased the rate of light induced oxygen consumption in all solutions. Measurements have revealed very similar oxygen consumption efficiency for TPPS4 and Ce6. The normalized consumption rate was three times lower for AlPcS4. In the presence of BSA the photobleaching rate for AlPcS4 was three times higher while that for Ce6 was one and a half time higher than the rates of photobleaching obtained in pure solutions. Conclusions: Light induced oxygen consumption in the aqueous solutions of photosensitizers can be affected depending on their distinctive structural features, combined action of internal and external factors, such as concentration and presence of suitable substrate. Increased oxygen consumption in the presence of BSA can be attributed to a non-specific phenomenon typical for all studied sensitizers - generated singlet oxygen is consumed for the substrate oxidation. The type I photosensitization mechanism seemed to be predominant in the photobleaching of AlPcS4 observed in complex solutions.
PL
Podstawy: Większość substancji fotouczulających wykorzystywanych w terapii fotodynamicznej podlega fotodegradacji, rozkładowi pod wpływem naświetlania. Procesowi temu towarzyszy zjawisko ubytku tlenu z powierzchni naświetlanej. Cele: Przedstawiono badania spektroskopowe dotyczące zjawiska fotowybielania oraz zużycia tlenu trzech hydrofilowych substancji fotouczulających drugiej generacji. Materiał i metody: Badano ftalocyjaninę (ALPcS4), me-so-tetra (sulfonatofenylo)-porfirynę (TPPS4) oraz chloryn e6 (Ce6). Testy przeprowadzono w czystych roztworach wodnych domieszkowanych albuminą surowicy bydlęcej (BSA). W badaniach porównawczych wykorzystano wygaszacz tlenu singletowego: azydek sodu. Wyniki: Ekspozycja na światło laserowe nie wywołała efektu fotowybielania w przypadku TPPS4, byl on też nieznaczny w przypadku ALPcS4. Gwałtowną fotodestrukcję zaobserwowano w przypadku chlorynu e6. Podczas naświetlania, poza roztworem chlorynu e6 (6,7x10 'M), nie zaobserwowano zużycia tlenu. We wszystkich roztworach domieszkowanych BSA ekspozycja na światło znacząco podwyższyła współczynnik zużycia tlenu. Wyniki badań wykazały bardzo podobny poziom wydajności zużycia tlenu dla TPPS4 oraz Ce6. Jednakże w przypadku ALPcS4, znormalizowany współczynnik wydajności zużycia gazu wykazywał trzykrotnie niższą wartość. Współczynnik fotowybielania ALPcS4, w obecności BSA, był trzykrotnie wyższy, natomiast Ce6 półtora razy wyższy, w stosunku do wartości otrzymanych w roztworach niedomieszkowanych. Wnioski: Zużycie tlenu, będące wynikiem ekspozycji na światło, mierzone w roztworach wodnych fotouczulaczy, jest zależne od strukturalnych cech badanych fotosensybilizatorów, połączonego oddziaływania wewnętrznych oraz zewnętrznych czynników, takich jak koncentracja roztworu, obecność odpowiedniego substratu, podłoża. Podwyższone zużycie tlenu w obecności BSA może być przypisane nieswoistemu zjawisku typowemu dla wszystkich badanych fotouczulaczy - wytwarzany tlen jest zużywany w procesie utleniania substratu. Mechanizm fotouczulania typu I wydaje się przeważający w procesie fotodestrukcji ALPcS4, zaobserwowanej w roztworach złożonych.
5
Content available remote Oxygen depletion during illumination of photosensitizers in aqueous solutions
Valanciunaite J., Zerebcova J., Streckyte G., Bagdonas S., Rotomskis R.
Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna
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2004
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Vol. 10, nr 1-2
38-38
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