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331.
332.
The effect of invertebrate predation pressure by the cladoceran Leptodora kindti on the population structure of Daphnia galeata and D. hyalina has been estimated by analyzing the occurrence frequency of the normal and spined morphotypes in Lake Baikal. It is shown
that the growth of L. kindti population density leads to an increase in the proportion of the spined morphotype, while that of that of the normal morphotype
decreases. 相似文献
333.
V. N. Orlov Yu. M. Borisov S. Yu. Irkhin A. A. Kovaleva 《Russian Journal of Ecology》2010,41(6):519-523
The distribution of three chromosome races (Moscow, Western Dvina, and Seliger) of the common shrew Sorex araneus L. in the zone of contact between their ranges in the Valdai Heights (32°00′ E, 57°00′ N) is discussed. The area co-inhabited
by all the three races is extremely small. Representatives of all the three races have been captured on only one trap line,
although there are no obstacles to the expansion of shrews. The extremely small area co-inhabited by the three races, as well
as the strictly parapatric distribution of the Moscow and Western Dvina races, may be related with competition forms such
as avoidance of contacts and separation of ecological niches. 相似文献
334.
Using the long-tailed tit (Aegithalos c. caudatus) as an example of the so-called irruptive species, the ecophysiological characteristics (body mass, fat reserves) and migration
speed during autumn period were analyzed. The mean body mass and the median fat score did not depend on the number of migrating
individuals. There was no evidence of the so-called stress in birds, participating in migration: migrants had even higher
fat reserves than residents, while no significant difference in the body mass was recorded. The increase in fat reserves in
the long-tailed tit during migration period was similar to the seasonal changes in energy reserves known for typical migrants.
This makes it possible for late-migrating individuals to maintain higher total speed of migration compared to early-migrating
ones. Basing on the obtained data, we conclude that the ecophysiological characteristics of the long-tailed tits migrating
in autumn are similar to those of regular migrants. 相似文献
335.
A. V. Artem’ev 《Russian Journal of Ecology》2010,41(5):418-421
On the basis of long-term studies on the ecology of pied flycatcher in Karelia, it has been shown that male nonparticipation
in nestling feeding is due to the course of postnuptial molt rather than to the mode of mating relationships, as it was considered
previously. This is confirmed by the results of selective capture of birds that have stopped to feed their brood. It is suggested
that reduction of parental care is associated with changes in the hormonal balance of molting birds. 相似文献
336.
337.
The abundance of terrestrial arthropods in the Orenburgskii Nature Reserve has decreased since its establishment in 1989.
At present, this parameter fluctuates considerably, and the species composition of arthropods is changing in favor of xerobiontic
and eurybiontic species. These changes result from the absence of grazing load as well as from periodic fires. Therefore,
it is necessary to organize controlled livestock grazing and reliable fire protection in reserved areas. 相似文献
338.
Unrine JM Tsyusko OV Hunyadi SE Judy JD Bertsch PM 《Journal of environmental quality》2010,39(6):1942-1953
To investigate the role of particle size on the oxidation, bioavailability, and adverse effects of manufactured Cu nanoparticles (NPs) in soils, we exposed the earthworm Eisenia ferida to a series of concentrations of commercially produced NPs labeled as 20- to 40-nm or < 100-nm Cu in artificial soil media. Effects on growth, mortality, reproduction, and expression of a variety of genes associated with metal homeostasis, general stress, and oxidative stress were measured. We also used X-ray absorption spectroscopy and scanning X-ray fluorescence microscopy to characterize changes in chemical speciation and spatial distribution of the NPs in soil media and earthworm tissues. Exposure concentrations of Cu NPs up to 65 mg kg(-1) caused no adverse effects on ecologically relevant endpoints. Increases in metallothionein expression occurred at concentrations exceeding 20 mg kg(-1) of Cu NPs and concentrations exceeding 10 mg kg(-1) of CuSO4. Based on the relationship of Cu tissue concentration to metallothionein expression level and the spatial distribution and chemical speciation of Cu in the tissues, we conclude that Cu ions and oxidized Cu NPs were taken up by the earthworms. This study suggests that oxidized Cu NPs may enter food chains from soil but that adverse effects in earthworms are likely to occur only at relatively high concentrations (> 65 mg Cu kg(-1) soil). 相似文献
339.
This study describes the spatial variability in nitrogen (N) transformation within a constructed wetland (CW) treating domestic effluent. Nitrogen cycling within the CW was driven by settlement and mineralization of particulate organic nitrogen and uptake of NO3-. The concentration of NO3- was found to decrease, as the delta15N-NO3- signature increased, as water flowed through the CW, allowing denitrification rates to be estimated on the basis of the degree of fractionation of delta15N-NO3-. Estimates of denitrification hinged on the determination of a net isotope effect (eta), which was influenced byprocesses that enrich or deplete 15NO3- (e.g., nitrification), as well as the rate constants associated with the different processes involved in denitrification (i.e., diffusion and enzyme activity). The influence of nitrification on eta was quantified; however, it remained unclear how eta varied due to variability in denitrification rate constants. A series of stable isotope amendment experiments was used to further constrain the value of eta and calculate rates of denitrification, and nitrification, within the wetland. The maximum calculated rate of denitrification was 956 +/- 187 micromol N m(-2) h(-1), and the maximum rate of nitrification was 182 +/- 28.9 micromol N m(-2) h(-1). Uptake of NO3- was quantitatively more important than denitrification throughoutthe wetland. Rates of N cycling varied spatially within thewetland, with denitrification dominating in the downstream deoxygenated region of the wetland. Studies that use fractionation of N to derive rate estimates must exercise caution when interpreting the net isotope effect. We suggest a sampling procedure for future natural abundance studies that may help improve the accuracy of N cycling rate estimates. 相似文献
340.
The toxicity and bioaccumulation of two heavy metals—lead (Pb) and cadmium (Cd)—in a semi-aquatic plant, Colocasia esculenta (L. Schott), from a synthetic heavy metal solution were studied. Young plants of equal size were grown hydroponically in shallow raceways containing Hoagland medium amended with 20, 40, and 60 mg l?1 of Pb and 2, 4, and 6 mg l?1 of Cd. The medium containing heavy metals was allowed to flow through the raceways with a change in influent heavy metal solution on every 5th day. The experiment was continued for 20 days. A set of control raceways—one comprised of nutrient medium with heavy metal supplements, devoid of plants, and another with the plants and nutrient medium having no metal supplement—was also simultaneously run. Chlorosis in the leaves was the prominent toxicity symptom observed due to Pb and Cd on the test plants. A significant decrease in the relative growth, biomass productivity, and total chlorophyll content were noticed in the plants with an increase in concentration of metal supplement in the solution and exposure time. Both metals accumulated to higher concentrations in the roots than in shoots, suggesting that the metals were bound to the root cells and their translocation to the leaves was limited. The results of the 20-day-long experiments indicate that from a phytoremediation perspective, C. esculenta is a promising plant species for remediation of wastewater polluted with lower concentrations of Pb and Cd. 相似文献