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Możliwe skutki wpływu zmian klimatycznych na ekologiczne funkcjonowanie płytkich jezior, na przykładzie jeziora Loenderveen, Holandia

Annals of Warsaw University of Life Sciences - SGGW Land Reclamation 01/2007; 38:95-104. DOI: 10.2478/v10060-008-0026-1
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    ABSTRACT: A five-year zooplankton study (1982–86) on three shallow and highly eutrophic lakes in the Loosdrecht area (The Netherlands) did not reveal any significant changes following the considerable reduction in external P-loading (from about 1.0 g to 0.3 g P m–2 year–1) since mid-1984.The recent annual fluctuations in the rotifer and crustacean densities are within the range of those found before the restoration measure became operative. A decrease in the average size of the crustaceans and an absence of large-bodied forms reflects an increased fish predation rather than a change in the quality or quantity of their sestonic food ( < 150="" m)="" which="" continues="" to="" be="" dominated="" by="" filamentous="" cyanobacteria="" and="">Prochlorothrix hollandica, a prochlorophyte discovered in these lakes recently.
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    ABSTRACT: The underwater light field in 7 lakes in the Loosdrecht lake area was measured in situ. Subsurface upwelling irradiance and irradiance reflectance, together with estimations of scattering and laboratory measurements of absorption by aquatic humus and particulate matter, enabled an analysis of the spectral signature of these waters. Aircraft imaging spectrometer measurements of upwelling radiance at 1 km altitude were used to simulate the PMI Chlorophyll #1, the CAESAR Inland Water Mode spectral bandsets and the Thematic Mapper bands 1 to 4. This made it possible to compare the effects of spectral band width and selection on the estimation of water quality parameters. Correlations increased to r > 0.94, at a significance level of 1% for the simulated C-IWM data with the 6 water quality parameters. Images of the PMI Chlorophyll #1 and of the TM were analysed and found to be in accordance with the statistical modelling results.A significant increase in correlation of remote sensing data with water quality parameters can be achieved through the selective use of 10 to 20 nm wide bands in the spectral range of 500 to 720 nm in these eutrophic waters. Sum of chlorophyll a and phaeopigments, seston dry weight, Secchi disc transparency, and coefficients for vertical attenuation of light, absorption and scattering can be estimated accurately. TM image data for water quality assessment is of limited use due to the relatively low spectral and radiometric resolution. However, the revisit capability and relatively low price per area are positive aspects of these satellite images.
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    ABSTRACT: Climate change will alter freshwater ecosystems but specific effects will vary among regions and the type of water body. Here, we give an integrative review of the observed and predicted impacts of climate change on shallow lakes in the Netherlands and put these impacts in an international perspective. Most of these lakes are man-made and have preset water levels and poorly developed littoral zones. Relevant climatic factors for these ecosystems are temperature, ice-cover and wind. Secondary factors affected by climate include nutrient loading, residence time and water levels. We reviewed the relevant literature in order to assess the impact of climate change on these lakes. We focussed on six management objectives as bioindicators for the functioning of these ecosystems: target species, nuisance species, invading species, transparency, carrying capacity and biodiversity. We conclude that climate change will likely (i) reduce the numbers of several target species of birds; (ii) favour and stabilize cyanobacterial dominance in phytoplankton communities; (iii) cause more serious incidents of botulism among waterfowl and enhance the spreading of mosquito borne diseases; (iv) benefit invaders originating from the Ponto-Caspian region; (v) stabilize turbid, phytoplankton-dominated systems, thus counteracting restoration measures; (vi) destabilize macrophyte-dominated clear-water lakes; (vii) increase the carrying capacity of primary producers, especially phytoplankton, thus mimicking eutrophication; (viii) affect higher trophic levels as a result of enhanced primary production; (ix) have a negative impact on biodiversity which is linked to the clear water state; (x) affect biodiversity by changing the disturbance regime. Water managers can counteract these developments by reduction of nutrient loading, development of the littoral zone, compartmentalization of lakes and fisheries management.
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