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201.
Raoul Beunen Catharinus F. Jaarsma Rob N. A. Kramer 《Journal of Coastal Conservation》2004,10(1):109-118
Accurate and sufficiently detailed information about recreation-related use of dune areas is necessary for their management.
Long-term monitoring can provide this information. This paper presents the visitor counting programme used in the Meijendel
dune area since 1992. The data collected during the first ten years are used to evaluate the method. The combination of mechanical
vehicle counts and additional visual counts proved to be reliable and produced an accurate data set. Costs could be reduced
through eventually reducing the number of counting locations and limiting the number of visual counts. 相似文献
202.
In the routine São Paulo state (Brazil) surface water quality-monitoring program, which includes the Salmonella microsome mutagenicity assay as one of its parameters, a river where water is taken and treated for drinking water purposes has repeatedly shown mutagenic activity. A textile dyeing facility employing azo-type dyes was the only identifiable source of mutagenic compounds. We extracted the river and drinking water samples with XAD4 at neutral and acidic pH and with blue rayon, which selectively adsorbs polycyclic compounds. We tested the industrial effluent, raw, and treated water and sediment samples with YG1041 and YG1042 and compared the results with the TA98 and TA100 strains. The elevated mutagenicity detected with YG-strains suggested that nitroaromatics and/or aromatic amines were causing the mutagenicity detected in the samples analyzed. Positive responses for the blue rayon extracts indicated that mutagenic polycyclic compounds were present in the water samples analyzed. The mutagen or mixture of mutagens present in the effluent and water samples cause mainly frameshift mutations and are positive with and without metabolic activation. The Salmonella assay combined with different extraction procedures proved to be very useful in the identification of the origin of the pollution and in the identification of the classes of chemical compounds causing the mutagenic activity in the river analyzed. 相似文献
203.
Tamara Fraizer 《Behavioral ecology and sociobiology》1997,41(6):423-434
I develop a state-based dynamic model of behavior to demonstrate that size-dependent differences in temperature tolerances
are not necessary to account for the activity of small male digger wasps late in the day. In the model, males defend or patrol
the nesting area, wait near nests, or feed away from the nesting area depending on time of day, energy reserves and size rank.
I assume a large male competitive advantage, so mating opportunities decrease with size rank for territorial or patrolling
males and are rare for all waiting males; the costs of patrolling or defense are higher than the costs of waiting. If energy
reserves of all males are initially small, all males alternate feeding and territorial or patrolling behavior. If energy reserves
are initially large, large males patrol or maintain territories until they risk starvation and leave the area to feed. At
this time, smaller males that have conserved their resources by waiting and feeding may defend territories or patrol. I simulate
the behavior of three populations representing two species of Microbembex by assuming large initial energy reserves for populations in which males were territorial and small initial reserves for
populations in which males patrolled, and then convert the predicted time of activity to temperature using local regressions
from field studies. Temporal patterns in the activity of large and small males were similar to those actually observed, and
relationships between size and temperature predicted by the model corresponded to most observations and were sometimes positive.
Thus, the delayed activity of smaller males does not correspond to activity at higher temperatures and is probably not attributable
to size-dependent thermal tolerances, but may represent a temporal displacement of mating activity due to intra-sexual competition
and mediated by energetics. The model makes testable predictions on the timing of feeding and depletion of energy reserves
in relation to size and initial energy state, and suggests how differences among species may influence the temporal and spatial
organization of male mating behavior.
Received: 27 February 1997 / Accepted after revision: 26 July 1997 相似文献
204.
Alberto Velando Roxana Torres Irene Espinosa 《Behavioral ecology and sociobiology》2005,58(2):175-180
Sexual selection models suggest that female choice is based on male traits that indicate their genetic or environmental condition, consequently enhancing her reproductive success by direct or indirect benefits. We investigated the relationship between male foot colour and offspring condition in the blue-footed booby, a socially monogamous seabird, with conspicuous and variably condition-dependent coloured feet that are selected by females. In a cross-fostering experiment, we found that chick condition was related to the foot colour of the foster father and, to some extent, to the foot colour of the genetic father; thus overall, the fathers sexual ornamentation (genetic and foster) explained 32% of variance of chick condition. These data suggest that foot colour, a dynamic sexually selected trait, is mostly a signal of parental contribution. In species in which males provide parental care, females may choose mates with higher parental ability. Overall, our data suggest that colourful integuments are honest signals of parental ability.Communicated by J. Graves 相似文献
205.
Boelens Richard G. V. 《Journal of Coastal Conservation》1996,2(1):169-174
The Irish Sea's distinctive hydrographic features present unique opportunities for research into the complex processes that
regulate shelf-sea ecosystems. Such studies are essential in developing capabilities to detect and evaluate change in marine
environments. A 1993 review showed almost 230 projects underway on the Irish Sea, spanning all the major fields of marine
science. But a large proportion of research projects failed to indicate the purpose of the work; overall, there was a remarkable
absence of clarity and specificity in the objectives. Progress in some fields is also hampered by insufficient coordination
and cohesion; at present there are no standing arrangements between Ireland and the United Kingdom that provide for bilateral,
co-ordination of scientific work in the area. There is clearly a need for a more planned and integrated Irish Sea science
programme to provide information for management purposes and also to advance scientific understanding of the components and
functions of Irish Sea ecosystems, and how and why they change with time. There is a common belief that the first of these
predominantly involves monitoring, and the second research. However, the paper cautions that this is a dubious and unnecessary
distinction. A strategy aimed at better integration of research and monitoring (e.g. a framework of linked objectives and
targets) could substantially increase the information dividend from current investments in Irish Sea science. Based on a joint
Irish/UK review, this paper outlines studies and approaches that are seen as key elements of a future, more relevant and costeffective
research programme for the Irish Sea. 相似文献
206.
The tactics of mutual mate choice and competitive search 总被引:9,自引:0,他引:9
Rufus A. Johnstone 《Behavioral ecology and sociobiology》1997,40(1):51-59
A model of mutual mate choice is described, formulated as a dynamic game, which yields predictions about mating behaviour
under the influence of time constraints, choice costs and competition for mates. These variables were examined because they
may result in a change in the distribution of qualities among unmated individuals of both sexes over the course of the breeding
season. The model predicts that mutual choice gives rise to assortative mating, although high costs of choice and/or inaccurate
assessment both lead to lower overall correlations between the qualities (or the attractiveness) of mates. When all individuals
are present from the start of the breeding season, the correlation between the qualities of individuals pairing at a given
time declines throughout the season, so that mates are more closely matched among individuals who pair early than among those
who pair late (and extra-pair copulation may thus be more common among the latter). Delayed arrival of lower-quality individuals
may, however, lead to an increase in this correlation with time during the early part of the season. The mean quality of unmated
males and females declines over time, because more attractive individuals tend to mate sooner. As a result of this decline,
and because of time constraints, superior individuals become less choosy as the season progresses. If choice is costly, however,
then inferior individuals become more selective with time during the early part of the season, and the level of choosiness
peaks later for such individuals.
Received: 28 March 1996 / Accepted after revision: 21 September 1996 相似文献
207.
Invertebrate recolonization of fine-grained beneficial use schemes: An example from the southeast coast of England 总被引:1,自引:0,他引:1
The disposal of maintenance dredged material constitutes one of the most important problems in coastal zone management. To
minimise ecological impacts, a number of ‘beneficial use’ options have developed whereby the material is regarded as a potential
resource and used to recharge or recreate intertidal habitats. This paper presents the results of a sampling programme to
investigate the macrofaunal recovery rates, and the underlying mechanisms responsible for them, following a beneficial use
scheme involving the placement of fine-grained dredged material on a salt marsh in southeast England.
Three stations in the recharge area and three reference stations, located within the same salt marsh system, were selected.
These stations were sampled prior to recharge (recharge stations only) then 1 week, 3, 6, 12 and 18 months after the recharge.
Sediment redox potentials (1, 2 and 4 cm sediment depths) were also measured on each sampling occasion. The results indicated
a rapid recolonization of the fauna typical of the surrounding salt marsh channels. All univariate parameters had recovered
after 3 months after the recharge. Active post-juvenile immigration is likely to have been the predominant recovery process.
Multivariate data analysis revealed that the community structure of the recharge stations, however, did not progress towards
those of the reference sites. Natural spatial variability in community structure at the scale of the recharge-reference station
distance, and differences in eventual tidal elevations are factors responsible for these differences. The need to carefully
assess reference site suitability in monitoring beneficial use schemes is discussed. 相似文献
208.
A dynamic dilution system was used for the study of the influence of ozone on the sampling and storage of volatile organic
compounds (VOCs) at 0, 4, 7 and 14 days in “TO-Can” canisters at two ozone concentrations, 60 and 150 ppbv. Among the 31 ozone
precursors VOCs, a representative mixture containing five alkenes, five aromatics, acetylene and 1,3 butadiene was selected
using the Clausius–Clapeyron equation. Here, we demonstrate that the presence of ozone have no influence on the concentrations
of VOCs after 14 days storage period and consequently no problem of representativity of the sampling appears after 14 days
of storage. The main explanation is the degradation of ozone in contact with deactivated walls of canisters. 相似文献
209.
基于监测样本信息的水环境系统权重分配方法 总被引:4,自引:0,他引:4
针对水环境系统权重分配问题,从建筑系统客观背景入手,以环境因子监测样本资料为信息源,通过构造关联信息矩阵,并采用旋转正交转变换的主成分分析法,定量地描述了交五因子在整体系统的贡献,最后依贡献量大小识别对应各个因子的权重值,实例表明,该方法物理意义清晰结果客观合理。 相似文献
210.
大气污染预测预报研究 总被引:1,自引:0,他引:1
以排放到大气环境中的烟尘为例,进行大气污染预测预报,并利用保证率的概念表示预测的结果,为大气污染的预测预报工作提供了一种基本方法。 相似文献