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Csaba Vadadi-Fülöp Levente Hufnagel Katalin Zsuga 《Environmental monitoring and assessment》2010,163(1-4):125-138
Although numerous studies have focused on the seasonal dynamics of riverine zooplankton, little is known about its short-term variation. In order to examine the effects of sampling frequency and sampling effort, microcrustacean samples were collected at daily intervals between 13 June and 21 July of 2007 in a parapotamal side arm of the river Danube, Hungary. Samples were also taken at biweekly intervals from November 2006 to May 2008. After presenting the community dynamics, the effect of sampling effort was evaluated with two different methods; the minimal sample size was also estimated. We introduced a single index (potential dynamic information loss; to determine the potential loss of information when sampling frequency is reduced. The formula was calculated for the total abundance, densities of the dominant taxa, adult/larva ratios of copepods and for two different diversity measures. Results suggest that abundances may experience notable fluctuations even within 1 week, as do diversities and adult/larva ratios. 相似文献
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How do distinct visual stimuli help bumblebees discover flowers before they have experienced any reward outside of their nest? Two visual floral properties, type of a pattern (concentric vs radial) and its position on unrewarding artificial flowers (central vs peripheral on corolla), were manipulated in two experiments. Both visual properties showed significant effects on floral choice. When pitted against each other, pattern was more important than position. Experiment 1 shows a significant effect of concentric pattern position, and experiment 2 shows a significant preference towards radial patterns regardless of their position. These results show that the presence of markings at the center of a flower are not so important as the presence of markings that will direct bees there. 相似文献
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Several organism communities serve as ecological and environmental indicators to detect changes in human-impacted habitats. However, the composition of indicator communities may vary because of natural variation in addition to the changes associated with human disturbances. This meta-analysis compared the natural variation of oribatid mite assemblages, a good indicator model group in soil ecosystems, with their deviations associated with disturbance using diversity and dissimilarity indices and three human disturbance types. Literature data were collected about oribatid mite assemblages from natural and disturbed habitats. Human disturbances consisted of agriculture, heavy metal pollution and forest management. Biodiversity indices (Shannon and Berger-Parker) and dissimilarity indices (Jaccard and Bray-Curtis) were calculated among natural habitats and between disturbed and control habitats at the species and genus level. We considered oribatid mite assemblages as effective community-level indicators when the methods separated the differences of assemblages between disturbed and control habitats from their varieties among natural habitats. In addition, the study analysed the correlation between these indices and environmental variables of the study sites. Oribatid mite assemblages performed high indication strength with Bray-Curtis index for agricultural disturbances since dissimilarity values between disturbed and control habitats were as high as between different natural habitats and higher than among the same types of natural habitats. Genus-level values showed similar results to the species level. This approach may be useful to test the effectiveness of other indicator groups and methods. 相似文献
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A new approach is proposed for the environmental impact assessment of fresh waters. New indices and the cenological values of aquatic and semiaquatic bug (Hemiptera) species have been obtained through multivariate analysis based on the species list of 157 localities in Hungary. The 45 species involved in this study can be characterized by their preference for habitat types on a linear scale ranging from small, shallow waters to large, deep waters. The habitats themselves can be characterized by the added cenological values of the species found. 相似文献
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Climate change has serious effects on the setting up and the operation of natural ecosystems. Small increase in temperature
could cause rise in the amount of some species or potential disappearance of others. During our researches, the dispersion
of the species and biomass production of a theoretical ecosystem were examined on the effect of the temperature–climate change.
The answers of the ecosystems which are given to the climate change could be described by means of global climate modelling
and dynamic vegetation models. The examination of the operation of the ecosystems is only possible in huge centres on supercomputers
because of the number and the complexity of the calculation. The number of the calculation could be decreased to the level
of a PC by considering the temperature and the reproduction during modelling a theoretical ecosystem, and several important
theoretical questions could be answered. 相似文献
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Mirela Miclean Oana Cadar Levente Levei Lacrimoara Senila Alexandru Ozunu 《Journal of environmental science and health. Part. B》2013,48(9):595-601
ABSTRACTThe Cd, Cu, Pb and Zn contents in home-grown crops in a former mining district were determined in order to evaluate the non-carcinogenic long-term potential health risk related to crop consumption. The potential health risk was investigated by estimating the daily intake and the hazard quotients. For all crop categories, the daily intake and the target hazard quotient were below the threshold values for Cd, Cu, and Zn. The daily intake of Pb exceeded the oral reference dose, while the target hazard quotient for vegetables was above 1, indicating a potential health risk. The total target hazard quotient for the individual metals decreased in the following order: Pb>Cd>Cu>Zn. This study confirmed that the daily consumption of crops grown in contaminated soils could pose health risks to humans. 相似文献
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Cs. Vadadi-Fülöp D. Türei Cs. Sipkay Cs. Verasztó Á. Drégelyi-Kiss L. Hufnagel 《Environmental Modeling and Assessment》2009,14(5):563-576
In the years 2004 and 2005, we collected samples of phytoplankton, zooplankton, and macroinvertebrates in an artificial small
pond in Budapest (Hungary). We set up a simulation model predicting the abundances of the cyclopoids, Eudiaptomus zachariasi, and Ischnura pumilio by considering only temperature and the abundance of population of the previous day. Phytoplankton abundance was simulated
by considering not only temperature but the abundances of the three mentioned groups. When we ran the model with the data
series of internationally accepted climate change scenarios, the different outcomes were discussed. Comparative assessment
of the alternative climate change scenarios was also carried out with statistical methods. 相似文献