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The marine species richness (MSR) recorded in 159 sandy beach surveys was analysed in relation to beach width (W). MSR is the number of macrobenthic species collected in a standard intertidal transect survey, excluding insects. Beach width (W) was estimated by dividing the spring tide range [m] by the beach face slope, to give a value in [m]. The relationship between MSR and W was best described by a semilog (exponential) model, which was highly significant: MSR = −5.2+ 10.8 logW. The fit of a power model (MSR = cWz) was also significant. The steep slope of the curve for a power model (z = 0.49) suggests that beaches function as isolated rather than contiguous habitats and that the nature of the habitat becomes more benign as beaches widen. There are some latitudinal effects, with tropical beaches displaying a higher species-area relationship for any beach width than other regions.
The article reports on the current state of the sipunculan fauna of the central and southern parts of the Barents Sea. The main quantitative parameters (biomass and abundance) of the sipunculan populations are obtained, and the contribution of sipunculids to the total benthos biomass is assessed. The major factors causing long-term variations in Sipunculidae distribution and abundance are evaluated for the area in question. The investigations show that the most commonly encountered sipunculan species are Nephasoma diaphanes diaphanes, N. abyssorum abyssorum and Phas- colion strombus strombus. The main contribution to the total benthos biomass comes from the two species most typical of the Barents Sea benthic fauna: Golfingia margaritacea margaritacea and G. vulgaris vulgaris. It is possible that the reduction in Golfingia biomass between the 1970s and 1990s, described in the article, is due to changes in the sampling methodology.
Research was conducted on the number, secondary production and physiological properties of benthic bacteria in the eutrophic Lake Chełmżyńskie. It was found that the number of psychrophilic bacteria (CFU) occurring in the bottom sediments of the studied lake and the rate of bacterial production (BP) were all characterized by a distinct seasonal variability and depended on the location of the study site and the type of bottom sediments (ANOVA, p-value <0.05). The maximum total number of bacteria (TNB), CFU and BP were observed in summer. Muddy sediments were characterized by a greater number of bacteria than sandy ones. A higher number of heterotrophic microorganisms and greater rate of secondary production were found at the sites located in the part of the studied waterbody near the town than at the sites located far from the town. The most numerous benthic bacteria were strains of hydrolyse fat, protein and cellulose. The least numerous were pectinolytic and chitinolytic bacteria.
In looking for factors affecting Chironomus plumosus (L.) abundance and its fluctuations − the comparison of its numbers has been done in the bottom (at 6 m depth) and in “mesocosms” – trays with the same bottom sediment elevated 0.4-1.2 meter above the bottom. The experiment was carried out, in a shallow, strongly eutrophic, polymictic, lowland dam reservoir, where theabundance of Chironomus is among the highest in nature. The total abundance was on the average several times higher and more stable and larvae developed more quickly in trays over the bottom than in the same mud at the bottom. All this was probably due to better and more stable oxygen conditions above the bottom than at it’s very surface. Usually no differences in the abundance were found between levels 0.4, 0.8 and 1.2 m above the bottom, what indicates that conditions at all these levels were similar and different from those at the very bottom. The average density, and especially spring peak numbers in and above the bottom, were much higher in the year 1993 than in 1996 (the ratio of average numbers 1993/96 being similar – 2.3 and 2.6 for the bottom and trays respectively). It was probably due to a higher food supply (mostly small diatoms) by rivers and also due to weaker spring water flow in 1993. The very strong decline from high spring peak numbers to summer minimum seems to result from interconnections between larvae and perhaps also increased fish pressure, after the spawning period.
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