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101.
102.
Nest-building by crested tit Parus cristatus males: an analysis of costs and benefits 总被引:1,自引:0,他引:1
In a population of crested tits in Belgium, one out of three breeding males participated in nest-building. Since variation in the amount of nest-building among 11 building males was low, analysis of male nest-building allowed a logistic regression design. The probability of building increased with male condition and for late nests. The effect of male condition decreased with date, and date was the only factor predicting nest-building for repeat broods. The effect of male condition on nest-building suggests that building entails important costs for males. Based on correlative data, we argue that building by males shortens the interval between the start of nest-building and the onset of egg-laying by about 5 days. Since clutch size, incubation and nestling time did not differ between early and late broods, male nest-building apparently affects fledging date. Since early fledgers (early dispersers) are more likely to settle in future winter flocks, building behaviour by crested tit males should be favoured by natural selection. So far, male nest-building in hole-breeding birds might have been overlooked due to the widespread use of artificial nest-boxes in behavioural studies. 相似文献
103.
Lakshminarayana JS O'Neill HJ Jonnavithula SD Léger DA Milburn PH 《Environmental pollution (Barking, Essex : 1987)》1992,76(3):201-210
Preliminary results are reported from a co-operative study between Agriculture Canada and Environment Canada on environmental impacts of atrazine measured in a field stream receiving agricultural drainage. Systematically, tile drained plots of known crop rotation, area, flow and pesticides use were used in the study. A maximum tile drainage concentration of 13.9 microg liter(-1) atrazine was measured while the maximum measured stream concentration was 1.89 microg liter(-1). Phytoplankton and zooplankton samples were collected on a bi-monthly basis during the growing season. The study indicated possible negative impacts of low concentrations of atrazine on planktonic drift populations, when natural stream flow was reduced, resulting in a lower dilution capacity. A 20 m section of the stream was affected by the tile drainage waters as measured by the resident biological community. Both atrazine and ambient environmental conditions were felt to be contributing to the measured results. No negative impacts on planktonic drift populations were evident beyond 50 m downstream of the tile drainage and stream confluence. 相似文献
104.
The aim of this paper is to examine the patterns of polychlorinated biphenyls (PCB) in the grey seals (Halichoerus grypus) from the Baltic, Northeast and Eastern England, and the St. Lawrence Estuary (Canada). In fact, the feeding habits of the ringed seal (Phoca hispida) include ingestion of major quantities of benthic crustaceans that might cause observed differences obtained in PCBs, whereas the grey seal feed mainly on fish. The profile (percent in mixture) of polychlorinated biphenyls (PCB) 101, 118, 138, 153, and 180, and the total of their concentrations in mg/kg lipid in grey seals from the Baltic, from Northeast and Eastern England, and from the St. Lawrence estuary (Canada), were examined by principal component analysis (PCA). When considering the possible effects of consuming seafood by the grey seal, it is necessary to characterize populations and individuals according to the amounts they consume, since populations in different parts of the world are likely to show big differences in their consumption of seafood. The patterns differ between juveniles and adult animals, but the gender of adults and geography do not appear to play a role. 相似文献
105.
Martyn N. Futter Lars Högbom Salar Valinia Ryan A. Sponseller Hjalmar Laudon 《Ambio》2016,45(2):188-202
We present a framework for evaluating and communicating effects of human activity on water quality in managed forests. The framework is based on the following processes: atmospheric deposition, weathering, accumulation, recirculation and flux. Impairments to water quality are characterized in terms of their extent, longevity and frequency. Impacts are communicated using a “traffic lights” metaphor for characterizing severity of water quality impairments arising from forestry and other anthropogenic pressures. The most serious impairments to water quality in managed boreal forests include (i) forestry activities causing excessive sediment mobilization and extirpation of aquatic species and (ii) other anthropogenic pressures caused by long-range transport of mercury and acidifying pollutants. The framework and tool presented here can help evaluate, summarize and communicate the most important issues in circumstances where land management and other anthropogenic pressures combine to impair water quality and may also assist in implementing the “polluter pays” principle. 相似文献
106.
The flow of carbon from plant roots into soil supports a range of microbial processes and is therefore critical to ecosystem function and health. Pollution-induced stress, which influences rhizosphere C flow is of considerable potential importance, and therefore needs to be evaluated. This paper reports on a method, based on reporter gene technology, for quantifying pollutant effects on rhizosphere C flow. The method uses the lux-marked rhizobacterium Pseudomonas fluorescens, where bioluminescence output of this biosensor is directly correlated with the metabolic activity and reports on C flow in root exudate. Plantago lanceolata was treated with paraquat (representing a model pollutant stress) in a simple microcosm system. The lux-biosensor response correlated closely with C concentrations in the exudate and demonstrated that the pollutant stress increased the C flow from the plantago roots, 24 h after application of the herbicide. The lux-reporter system therefore potentially offers a technique for use in assessing the impact of pollutant stress on rhizosphere C flow through the soil microbial biomass. 相似文献
107.
Forsberg A Söderlund S Frank A Petersson LR Pedersén M 《Environmental pollution (Barking, Essex : 1987)》1988,49(4):245-263
Concentrations of eleven metals (Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V and Zn) were determined in the brown seaweed Fucus vesiculosus collected from the Archipelago of Stockholm. Several factors which influence the metal content in the seaweed have been studied, including errors caused by epiphytes, sea exposure and differences depending on which part of the seaweed is analysed. It is concluded that, if all these factors are considered, Fucus vesiculosus plants are excellent bio-indicators of metal pollution. This is also demonstrated by a significant increase in metal content in transplanted Fucus vesiculosus near the city of Stockholm. The results from this investigation also indicate increasing metal concentrations, especially Cd, in samples from the northern parts of the Archipelago and the reason for this is discussed. 相似文献
108.
I. N. Sukhanova M. V. Flint G. Hibaum V. Karamfilov A. I. Kopylov E. Matveeva T. N. Rat'kova A. F. Sazhin 《Marine Biology》1988,99(1):1-8
The structure and some functional characteristics of the plankton community at the time of aExuviaella cordata red tide were investigated in Burgas Bay, Bulgaria, in May and June 1986. Characteristics of main plankton components (phyto-, bacterio-, nanoheterotrophic plankton, ciliates and mesoplankton) in the bloom area are presented. Development of theE. cordata bloom was determined by abiotic conditions among which eutrophication and salinity decrease caused the patchy character of its rapid development. Attainment of maximum red tide (ca. 1x109 cells l-1; 1x103 g m-3) from background (500 to 800x103 cells l-1; 600 mg m-3) took 3 to 7d. Growth rate () during that period was 1.2 to 2.2 doublings per day. A sharp bloom decline (3 to 4d) was caused by parasitic flagellates destroying the alga's chloroplast. Diel biomass losses due to grazing remained below 5%. Metabolites and degradation products ofE. cordata revealed no pronounced toxic effects on the other components of the planktonic community. The rapid bloom degradation due to the effects of parasitic flagellates indicates the high potential of ecosystem self-regulation. 相似文献
109.
Jos L. Mateos Paloma Fern ndez Del Pino Francisco J. Guti rrez Ma ero Marí a Ruiz Palomino Juan J. Colon Jos A. Lucas Garcí a Agustí n Probanza 《Chemistry and Ecology》2000,17(2):125-152
Microbial communities (phospholipid fatty acid pattern, bacterial growing strategies, eco-physiological index (EPI) and total bacteria counts, as a number of heterotrophic cuhurable bacteria), substrate-induced respiration (SIR), and nitrogen mineralization were studied in three Mediterranean soils at three different depth levels (A, B and C). Soils were experimentally treated with a final concentration of 1000 ppm of trace metals (Cu2+, Zn2+, Al3+, Fe2+, Pb2+, Ni2+, Mn2+, Cr3+ and Cd2+). Soils were stored in 571 plastic containers for one year, and watered with 1001 during this period. Leachate was recovered through a bottom tap. Samples of the three depths were studied. Soil microbial communities showed different effects to other studies presented in the literature, but carried out on non-Mediterranean soils. Dramatic differences were found between treated soils and untreated ones, but not between soils or horizons. the treated soil displayed a decrease in CFUs, SIR N-mineralization and EPI together with a dominance of r-growing strategists. the relative moles percent of several PLFAs, especially 15:0, 16: 1ω7, cy17: 0, br18:0 and 18: 1ω7 decreased because of the pollution of soils, whereas 10Me16, 18:2ω6, cy19:0, i16:0 and br17:0 showed higher values than in untreated soils. 相似文献
110.
Genetic Structure of a Mimosoid Tree Deprived of Its Seed Disperser, the Spider Monkey 总被引:1,自引:0,他引:1
Abstract: To assess the genetic consequences for a Neotropical tree of the loss of its main seed disperser, we compared the genetic structure of Inga ingoides in a site where the spider monkey (Ateles paniscus) was abundant and a site where it had been eliminated by subsistence hunting. Gene flow should be reduced in the site where the spider monkey is absent, and there should be a corresponding subpopulation differentiation of seedlings within the spatial range of the movements of these primates in the absence of between-site differences in allelic frequencies. At the microhabitat ( family) scale, seedlings growing under parent plants should be genetically more related in the absence of the spider monkey than in its presence. Subpopulation differentiation was smaller where the spider monkey was present ( four loci, FST = 0.011) than where it was absent ( four loci, FST = 0.053) for the first year of study, but not for the second year (three loci, FST = 0.005 vs. 0.003). The number of alleles in common among seedlings growing under parent plants was smaller in the presence of the spider monkey than in its absence, showing family genetic structure in the first generation for both years of study ( Mann-Whitney, z = −2.17, p = 0.03 and z = −2.72, p = 0.006 for 1996 and 1997, respectively). This family genetic structure in the first generation should accelerate the development of population genetic structure. Development of genetic structure might result in demographic changes, one of which would be a fitness reduction if the species were self-incompatible, as suggested for Inga by available evidence. Large birds and mammals are the main targets of subsistence hunting in the Neotropics. Extinction of seed-dispersing frugivores may result in pronounced changes in the demographic and genetic structure of tree species in Neotropical forests. 相似文献