Оцінка екологічного стану водосховищ гідроенергетичного призначення на р. Південний Буг за гідрогеологічними показниками

Проаналізовано особливості гідробіологічних угрупувань водосховищ гідроенергетичного призначення р.Південний Буг. Дослідження проведено за такими показниками: видовий склад, кількість, біомаса, трофічні характеристики, індекс сапробності за Пантле-Букком, за Балушкіною (для угрупувань бентосу), індекс видового різноманіття Шеннона окремо за чисельністю та біомасою, індекс Пареле, рибопродуктивність водосховищ

Cycling of carbon and oxygen in layers of marine microphytes; a simulation model and its eco-physiological implications

A mathematical simulation model was used to ascertain the relation between the diffusion of oxygen and inorganic carbon into layers of marine microphytes and the carbon metabolism of these microphytes. The simulation model included physiological and physico-chemical parameters and was validated using the few data available from the literature on production determinations, on oxygen and pH values, and on growth dynamics of natural populations. The model was tested with various modifications to mimic experiments with suspended algae and algal films on inert substrates, and also to simulate microphytobenthos in sediment cores with or without grazing. The simulated variations in oxygen concentrations and pH values over time scales of min and days were consistent with field and experimental observations. The model predicted upper limits of primary production and biomass observed in well developed natural populations; these limits are caused by a combination of oxygen accumulation and depletion of inorganic carbon resulting from diffusion limitations and the recirculation of organic carbon in photosynthetic, respiratory and excretory processes. The model calculations were used to check on the adequacy of the various methods used to determine the primary production of benthic microphytes

The Seasonal Succession Patterns of Diatom Species on an Intertidal Mudflat:An Experimental Analysis

The seasonal succession of seven dominant diatom species on a brackish intertidal mudflat in the Ems-Dollard estuary, The Netherlands, was found to follow simple recurring patterns in four successive years. Two species were especially abundant on the mudflat, Navicula salinarum being dominant in the cold seasons and N. pygmaea blooming mainly in summer. The wax and wane of these two species and their co-occurrence were analysed in experiments with oneor two-species cultures and with natural samples of sediment and algae, incubated in the laboratory. The importance of the following selection mechanisms was demonstrated: 1) temperature dependence of cell division, 2) interspecific competition in dense populations, 3) vertical zonation of species in micro-layers of the mud, 4) occurrence of stress factors e.g. desiccation, and 5) grazing by herbivorous meiofauna. The response of the two Navicula species generally agreed with their seasonal occurrence; e.g. N. pygmaea required higher temperatures for rapid cell division, was insensitive to temperatures over 30'C and survived partial desiccation more completely than N. salinarum. The relative resistance of N. pygmaea to grazing contributed to its abundance in summer. Parts of the seasonal succession patterns could be simulated using natural populations in experimental systems incubated under various combinations of temperature, irradiance level and exposure to desicccation