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311.
Nikitin AI Chumichev VB Valetova NK Katrich IY Kabanov AI Dunaev GE Shkuro VN Rodin VM Mironenko AN Kireeva EV 《Journal of environmental radioactivity》2007,96(1-3):138-143
Data on content of (90)Sr, (137)Cs, (239,240)Pu and (3)H in water of the Tobol-Irtysh part of the Techa-Iset-Tobol-Irtysh-Ob river system (through which the "Mayak" PA radioactive wastes are transported) are presented and discussed. The data were received in 2004-2005 under the ISTC project on radioecological monitoring of the Tobol and Irtysh rivers. Monthly observations of (137)Cs, (90)Sr and (3)H content in water in the area of the Tobol and Irtysh confluence have been conducted starting from May 2004. To obtain information on the investigated river system as a whole, the radioecological survey of the Tobol and Irtysh rivers at the section from the mouth of the Iset River to the confluence with the Ob River was carried out in 2004. It is shown that the impact of "Mayak" PA waste transport by (90)Sr is distinctly traced as far as the area of the Irtysh and Ob confluence. 相似文献
312.
Elena P. Kruchenkova Michael Goltsman Sergei Sergeev David W. Macdonald 《Die Naturwissenschaften》2009,96(4):457-466
The Arctic Fox Alopex lagopus semenovi population on Mednyi Island is completely isolated and subsists largely by scavenging on seabird colonies, which have remained
abundant and spatio-temporally predictable for many years. We compared population data at the beginning of 1976/1978 and some
time after 1994–2005, finding an 85% decline in fox numbers due to disease, to assess the effect of population size on social
structure. A total of 81 groups of known size and composition was observed during this 29-year period. Overall, helpers (usually
non-lactating yearling females) occurred in 25.7% of groups, and in 32.4% of groups there were two or three lactating females.
Female engagement in alloparental behaviour decreased, but not statistically significantly, after the decline in population
density. Total food availability was apparently constant throughout the study period, and therefore, the amount available
per individual was much higher later in the study. Both communally nursing females and helpers brought food and helped to
guard the litter. However, the benefits of communal rearing were unclear. While cubs were left without guards significantly
more rarely in the groups with an additional adult, the number of cubs weaned per lactating female was greater in groups with
one (3.93 ± 1.60), as opposed to two or three (3.06 ± 0.92), lactating females. Survival of cubs to 1 year of age in the groups
with two lactating females and/or with helpers was lower than that in the families with one lactating female without helpers (22.2% vs 32.2%). Fewer second-generation litters were
born to foxes produced by composite families than to those produced by pairs. Reproductive adults producing by pairs had,
on average, 1.23 (±1.72) second-generation litters. In groups that initially included additional adults, the average number
of second-generation litters per reproductive female was 0.21 (±0.49) and 0.46 (±0.81) litters per male. Thus, according to
three measures, increased group size had no apparent positive impact on reproductive success. The increased parental investment
and enhanced guarding of the cubs in the larger families could be beneficial under conditions of high population density and
a saturated biotope to which the island fox population was presumably adapted before the population crash in the late 1970s. 相似文献
313.
Daria Ryabchuk Mikchail Spiridonov Vladimir Zhamoida Elena Nesterova Aleksander Sergeev 《Journal of Coastal Conservation》2012,16(3):233-242
Traditionally the coastal zone of the easternmost (Russian) part of the Gulf of Finland has not been considered as an area of active litho- and morphodynamics, but a recent study has shown that the easternmost part of the coastal zone suffers from erosion. Within some coastal segments the shoreline recession rate reaches 2 ?C 2.5?m/year. As well as determining the hydrodynamic reasons for recent erosion acceleration, important geological and geomorphic features of coastal zone which influenced the lithodynamics were established. The Kurortny District of St.Petersburg is located along the northern coast of the Gulf of Finland to the west of the St. Petersburg Flood Protection Facility. It has special importance as a unique recreation zone of the North-West of Russia. Coastal erosion is one of the most serious problems of the area. The analysis of historical materials, archive aerial photographs and modern high-resolution satellite images have shown that advancing parts of coast are almost non-existant with most sections of the coast being eroded and further retreating. Field monitoring between 2004 and 2007 showed intense damage to sandy beaches during autumn and winter storms and progressive erosion of the dunes system. Among the most important natural reasons for the erosion processes are that the coastline is open to storm waves induced by westerly and south-westerly winds, the geological structure of coastal area (easily eroded Quaternary deposits) and a sediment deficit. In some areas sediment loss was the result of the submarine coastal slope morphology (a steep slope of a narrow submarine terrace within the area of sediment drift discharge), with erosion of an alongshore submarine sandy terrace and erosion runnels at the depth 8?C12?m. The situation becomes worse due to anthropogenic impact. The southern coastal zone dynamics are also very active. According to an aerial and satellite photos analysis from 1975?C1976 to 1989?C1990, sandy beaches to the west of Lebyazhye village were eroded up to 30?m, and near Bolshaya Izora village up to 70?m. The comparison of coastine GPSsurvey with old nautical and topographic charts published in the 1980s shows the considerable change. 相似文献
314.
315.
Xim Cerdá Elena Angulo Raphaël Boulay Alain Lenoir 《Behavioral ecology and sociobiology》2009,63(4):551-562
In social insects, the decision to exploit a food source is made both at the individual (e.g., a worker collecting a food
item) and colony level (e.g., several workers communicating the existence of a food patch). In group recruitment, the recruiter
lays a temporary chemical trail while returning from the food source to the nest and returns to the food guiding a small group
of nestmates. We studied how food characteristics influence the decision-making process of workers changing from individual
retrieving to group recruitment in the gypsy ant Aphaenogaster senilis. We offered field colonies three types of prey: crickets (cooperatively transportable), shrimps (non-transportable), and
different quantities of sesame seeds (individually transportable). Colonies used group recruitment to collect crickets and
shrimps, as well as seeds when they were available in large piles, while small seed piles rarely led to recruitment. Foragers
were able to “measure” food characteristics (quality, quantity, transportability), deciding whether or not to recruit, accordingly.
Social integration of individual information about food emerged as a colony decision to initiate or to continue recruitment
when the food patch was rich. In addition, group recruitment allowed a fast colony response over a wide thermal range (up
to 45°C ground temperature). Therefore, by combining both advantages of social foraging (group recruitment) and thermal tolerance,
A. senilis accurately exploited different types of food sources which procured an advantage against mass-recruiting and behaviorally
dominant species such as Tapinoma nigerrimum and Lasius niger. 相似文献
316.
We tested the relative contribution of leaf life span (LLS) and nutrient resorption efficiency (RE) to nutrient mean residence time (MRT) in plants. To do so, we introduced the use of elasticity analysis, which aims to measure the impact on MRT of a small change in one component, relative to the impact of equal changes in the other element. We also quantified the joint effect of LLS and RE on MRT, which required the calculation of the second derivatives of MRT with respect to LLS and RE. The estimation of the first derivatives showed that, although MRT increases linearly with LLS for a given value of RE, the relative effect of RE on MRT elasticity varies according to RE values; when RE > 0.5, the MRT's elasticity increases exponentially. The calculation of the second derivatives confirmed the importance of RE on MRT's variation. We used the results of the elasticity analysis to analyze how MRT responded to variation in LLS and nitrogen RE on MRT at the intra- and interspecific levels. For this, we used 18 plant species from three stages of a Mediterranean old-field succession, grown in a common garden experiment at two levels of nitrogen supply. 相似文献
317.
Life table demography of Ceriodaphnia dubia (Cladocera) exposed to copper at different levels and periods 总被引:1,自引:0,他引:1
Gama-Flores JL Castellanos-Paez ME Sarma SS Nandini S 《Journal of environmental biology / Academy of Environmental Biology, India》2007,28(3):691-696
We studied the demographic responses of Ceriodaphnia dubia exposed to copper at 3 different levels (0.1, 0.2 and 0.4 mg l(-1)) and at 4 exposure periods (3, 6, 12 and 24 hr) in addition to controls (without the heavy metal). The tested levels of Cu concentration and the chosen periods of exposure affected some demographic variables (average lifespan, gross and net reproductive rates and generation time). Depending on the heavy metal concentration and the period of exposure, the average lifespan of C. dubia varied from 18 to 24 day Net reproductive rates (NRR) ranged from 50 to 80 offspring per female per lifespan, while the rate of population increase (r) varied from 0.30 to 0.34 per day Though gross reproductive rates (especially at low and intermediate copper levels and shorter duration of exposure) showed significantly higher values than controls, both NRR and r were either unaffected or decreased. It is therefore necessary to regulate the release of untreated industrial effluents containing copper into freshwater ecosystems. Our study thus highlights the importance of including, not only toxicant concentrations but also exposure time, in ecotoxicological evaluations. 相似文献
318.
Chemotactile cues unintentionally left by animals can play a major role in predator–prey interactions. Specialized predators can use them to find their prey, while prey individuals can assess predation risk. However, little is known to date about the importance of chemotactile cues for generalist predators such as ants. Here, we investigated the response of a generalized predatory ant, Formica polyctena, to cues of two taxonomically distinct prey: a spider (Pisaura mirabilis) and a cricket (Nemobius sylvestris). In analogy, we studied whether crickets and spiders showed antipredator behavior in response to ant cues. When confronted with cues of the two prey species, Formica polyctena workers showed increased residence time and reduced movement speed, which suggests success-motivated searching behavior and thus increased foraging effort. The ants’ response did not differ between cues of the two prey species, coinciding with similar aggression and consumption rates of dead prey. However, the cuticular hydrocarbons, which likely resemble part of the potential cues, differed strongly between the species, with only few methyl-branched alkanes in common. This suggests that ants respond to multiple compounds left by other organisms with prey-search behavior. The two prey species, in turn, showed no detectable antipredator behavior in response to ant cues. Our study shows that ants can detect and respond to chemotactile cues of taxonomically and ecologically distinct prey species, probably to raise their foraging success. Using such chemotactile cues for prey detection may drastically increase their foraging efficiency and thus contribute to the high ecological success of ants. 相似文献
319.
Manuel Soler Liesbeth de Neve Gianluca Roncalli Elena Macías-Sánchez Juan Diego Ibáñez-Álamo Tomás Pérez-Contreras 《Behavioral ecology and sociobiology》2014,68(2):333-342
The post-fledging period is a critical phase for juvenile survival, and parental care provided during this period is a key component of avian reproductive performance. Very little is known about the relationships between foster parents and fledglings of brood parasites. Here, we present the results of a 5-year study about the relationships between fledglings of the non-evictor brood parasitic great spotted cuckoo (Clamator glandarius) and its magpie (Pica pica) foster parents. Sometimes, great spotted cuckoo and magpie nestlings from the same nest can fledge successfully, but most often parasitic nestlings outcompete host nestlings and only cuckoos leave the nest. We have studied several aspects of cuckoo post-fledging performance (i.e. feeding behaviour, parental defence and fledgling survival) in experimental nests in which only cuckoos or both magpie and cuckoo nestlings survived until leaving the nest. The results indicate that great spotted cuckoo fledglings reared in mixed broods together with magpie nestlings were disadvantaged by magpie adults with respect to feeding patterns. Fledgling cuckoos reared in mixed broods were fed less frequently than those reared in only cuckoo broods, and magpie adults approached less frequently to feed cuckoos from mixed broods than cuckoos from only cuckoo broods. These results imply that the presence of host's own nestlings for comparison may be a crucial clue favouring the evolution of fledgling discrimination; and furthermore, that the risk of discrimination at the fledgling stage probably is an important selection pressure driving the evolution of the arms race between brood parasites and their hosts. 相似文献
320.
In a context of increasing urban sprawl and water scarcity common to other Mediterranean cities, this article focuses on the
urban parks in the Region of Barcelona (Catalonia, Spain) to examine how these parks are distributed in this region and to
assess whether their design and management follow criteria adapted to Mediterranean environmental conditions, especially in
what concerns water use. In order to evaluate the environmental performance of these parks, we selected four factors possibly
influencing the adoption of park management practices at the local scale: urban density, population size of the municipality,
municipal income per capita, and political orientation of the city council. After determining the location and area of urban
parks in the region, we correlated these four explanatory factors with several management tasks extracted from two different
samples of parks (one of 315 parks and another of 125 parks) and a survey of 86 city councils. Results show that, in general,
urban parks were more frequent in large, dense, and left/green municipalities but that environmentally sound practices were
more common in small and low-density municipalities. We conclude that changes in certain practices (especially the substitution
of high water demanding species) could improve significantly the environmental performance of public spaces in large urban
areas with Mediterranean climates. Our observations may be pertinent for other cities interested in the provision of environmental
public goods such as parks that necessitate water for irrigation. 相似文献