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81.
Dampwood termites, Zootermopsis angusticollis (Isoptera: Termopsidae), mount an immune response to resist microbial infection. Here we report on results of a novel analysis that allowed us to electrophoretically assess changes in hemolymph proteins in the same individual before and after exposure to a pathogen. We demonstrate that contact with a sublethal concentration of the entomopathogenic fungus Metarhizium anisopliae (Deuteromycotina:Hypomycetes) induces the production of protective proteins in nymphs, pseudergates (false workers), and soldiers. Termites exposed to an immunizing dosage of fungal conidia consistently showed an enhancement of constitutive proteins (62–85 kDa) in the hemolymph as well as an induction of novel proteins (28–48 kDa) relative to preimmunization levels. No significant differences in protein banding patterns relative to baseline levels in control and naïve termites were observed. Incubating excised and eluted induced proteins produced by immunized pseudergates or immunized soldiers with conidia significantly reduced the germination of the fungus. The fungistatic effect of eluted proteins differed significantly among five colonies examined. Our results show that the upregulation of protective proteins in the hemolymph underscores the in vivo immune response we previously recorded in Z. angusticollis. 相似文献
82.
Most performance criteria which have been applied to train ecological models focus on the accuracy of the model predictions. However, these criteria depend on the prevalence of the training set and often do not take into account ecological issues such as the distinction between omission and commission errors. Moreover, a previous study indicated that model training based on different performance criteria results in different optimised models. Therefore, model developers should train models based on different performance criteria and select the most appropriate model depending on the modelling objective. This paper presents a new approach to train fuzzy models based on an adjustable performance criterion, called the adjusted average deviation (aAD). This criterion was applied to develop a species distribution model for spawning grayling in the Aare River near Thun, Switzerland. To analyse the strengths and weaknesses of this approach, it was compared to model training based on other performance criteria. The results suggest that model training based on accuracy-based performance criteria may produce unrealistic models at extreme prevalences of the training set, whereas the aAD allows for the identification of more accurate and more reliable models. Moreover, the adjustable parameter in this criterion enables modellers to situate the optimised models in the search space and thus provides an indication of the ecological model relevance. Consequently, it may support modellers and river managers in the decision making process by improving model reliability and insight into the modelling process. Due to the universality and the flexibility of the approach, it could be applied to any other ecosystem or species, and may therefore be valuable to ecological modelling and ecosystem management in general. 相似文献
83.
The nettle caterpillar, Darna pallivitta (Moore) (Lepidoptera: Limacodidae), is an invasive pest with established populations on three Hawai’ian islands. Indigenous
to Southeast Asia, D. pallivitta caterpillars cause defoliation of ornamental nursery stock and pose a human health hazard due to their urticating hairs that
can cause painful skin reactions. Identification of the pheromone component n-butyl (E)-7,9-decadienoate (E7,9-10:COOnBu) from D. pallivitta has made it possible to investigate the phenology and population dynamics using baited traps. Male captures in Jackson traps
baited with E7,9-10:COOnBu showed a vegetation preference for tall-grass fields and forest/grass interfaces over forest areas. Microlocation
preferences were also found for trap height, with over 65% of males being caught in traps suspended at 1 m, compared with
the traps at 3 and 5 m. Captures of male moths in traps baited with live females, and direct observations of female calling
behavior, showed peak activities 6–7 h after the onset of scotophase. This is a much later communication period than for D. bradleyi and D. trima and may provide a mechanism by which D. pallivitta maintains reproductive isolation in areas where all three species are present. Coastal and inland transects established in
eastern Hawai’i measured aspects of population fluctuations and radiation into new areas with relation to elevation and microclimate.
Population expansion was measured by comparing moth population means and 80% population boundaries over time. Both population
measures showed a higher expansion for the coastal transect. Differences in population expansion may be attributed in part
to temperature and elevation, while precipitation does not seem to have a strong effect. Both the behavioral and ecological
data collected can be used to optimize deployment of detection/control strategies and to predict population expansion/risk
assessment for establishing quarantine protocols for the nettle caterpillar. 相似文献
84.
森林溪流非木质残体的特征直接关系到流域源头水质环境以及森林生态系统碳及养分等物质的输出格局.为了解岷江上游水源源头高山森林生态系统溪流非木质残体的储量特征,于2013 年8 月高山森林溪流水量最大的季节,在研究区域海拔3 600 m 典型高山森林范围内,沿主河道两岸调查每条森林溪流的非木质残体储量,共找到18 条森林溪流汇入主河道,根据实地采样的可操作性和典型性,选择其中12 条溪流详细调查非木质残体储量,每条森林溪流从尽头到源头每隔10 m 设置一个长度为1 m,溪流实际宽度的样方(源头作为最后一个样方).将样方内所有非木质残体全部采集,低温保存,迅速带回实验室,分别按照树皮、树叶和直径小于1 cm 树枝分离,65 ℃烘干至恒重,测定各组分现存量.然后,将样品粉碎过筛,采用重铬酸钾氧化法测定凋落物有机碳含量,以不同组分现存量与其碳含量计算各组分的碳储量.结果表明:(1)该区域森林溪流非木质残体总现存量和总碳储量分别为657.25 kg 和262.96 kg,单位面积现存量和碳储量为439.70 g·m^-2 和175.92g·m^-2;(2)各溪流中直径小于1 cm 树枝占非木质残体总现存量和总碳储量的69.76%和73.41%,其次为树叶,树皮比例最小且不足10%;(3)尽管溪流长度、面积和流量与非木质残体各组分单位面积现存量和碳储量均无显著相关关系,但显著影响溪流非木质残体总现存量和总碳储量及其在各组分的分配比例;(4)相对于树皮,凋落树叶现存量和碳储量所占比例在流量较小溪流中相对较大.这些结果为深入认识高山森林流域水环境及其在森林生态系统中的重要作用提供新的思路和一定的科学依据. 相似文献
85.
86.
Development of a Bird Integrity Index: Measuring Avian Response to Disturbance in the Blue Mountains of Oregon, USA 总被引:1,自引:0,他引:1
Bryce SA 《Environmental management》2006,38(3):470-486
The Bird Integrity Index (BII) presented here uses bird assemblage information to assess human impacts to 28 stream reaches
in the Blue Mountains of eastern Oregon. Eighty-one candidate metrics were extracted from bird survey data for testing. The
metrics represented aspects of bird taxonomic richness, tolerance or intolerance to human disturbance, dietary preferences,
foraging techniques, and nesting strategies that were expected to be positively or negatively affected by human activities
in the region. To evaluate the responsiveness of each metric, it was plotted against an index of reach and watershed disturbance
that included attributes of land use/land cover, road density, riparian cover, mining impacts, and percent area in clearcut
and partial-cut logging. Nine of the 81 candidate bird metrics remained after eliminating unresponsive and highly correlated
metrics. Individual metric scores ranged from 0 to 10, and BII scores varied between 0 and 100. BII scores varied from 78.6
for a minimally disturbed, reference stream reach to 30.4 for the most highly disturbed stream reach. The BII responded clearly
to varying riparian conditions and to the cumulative effects of disturbances, such as logging, grazing, and mining, which
are common in the mountains of eastern Oregon. This BII for eastern Oregon was compared to an earlier BII developed for the
agricultural and urban disturbance regime of the Willamette Valley in western Oregon. The BII presented here was sensitive
enough to distinguish differences in condition among stream riparian zones with disturbances that were not as obvious or irreversible
as those in the agricultural/urban conditions of western Oregon. 相似文献
87.
Non-structural streambank stabilization, or bioengineering, is a common stream restoration practice used to slow streambank
erosion, but its ecological effects have rarely been assessed. We surveyed bank habitat and sampled bank macroinvertebrates
at four bioengineered sites, an unrestored site, and a comparatively less-impacted reference site in the urban Peachtree-Nancy
Creek catchment in Atlanta, GA, USA. The amount of organic bank habitat (wood and roots) was much higher at the reference
site and three of the bioengineered sites than at the unrestored site or the other bioengineered site, where a very different
bioengineering technique was used (“joint planting”). At all sites, we saw a high abundance of pollution-tolerant taxa, especially
chironomids and oligochaetes, and a low richness and diversity of the bank macroinvertebrate community. Total biomass, insect
biomass, and non-chironomid insect biomass were highest at the reference site and two of the bioengineered sites (p < 0.05). Higher biomass and abundance were found on organic habitats (wood and roots) versus inorganic habitats (mud, sand,
and rock) across all sites. Percent organic bank habitat at each site proved to be strongly positively correlated with many
factors, including taxon richness, total biomass, and shredder biomass. These results suggest that bioengineered bank stabilization
can have positive effects on bank habitat and macroinvertebrate communities in urban streams, but it cannot completely mitigate
the impacts of urbanization. 相似文献
88.
A straightened stream stretch with poor habitat heterogeneity was divided into a “control” section with a low amount of submerged woody debris and an experimentally “wood-enriched” downstream section to study the effect of enhanced habitat diversity on the benthic invertebrate community. The downstream section was enriched by fixing 25 wood packages constructed from 9–10 branches on the stream bottom. Succession processes occurring in the two stream sections were compared by chironomid exuviae drift from July to November 2000 and from April to August 2001. During the first sampling period, more drifting chironomid exuviae (medians of control vs. wood-enriched: 446 vs. 331, no significant difference) and total number of taxa (44 vs. 36, Wilcoxon signed-rank test P = 0.019) were recorded for the control section. Although species compositions of both stream sections were highly similar (Sørensen index: 0.83) the diversity in the wood-enriched section was distinctly lower compared to the control section (Shannon–Weaver index: 1.19 vs. 1.50). During the second sampling period, exuviae numbers remained higher in the control section (median: 326 vs. 166), but total numbers of taxa were nearly equal (51 vs. 49), as well as species diversity (Shannon–Weaver index: 1.67 vs. 1.64). The lower chironomid diversity observed during the first sampling period coincided with a gradual but significant change of the streambed morphology in the wood-enriched section. There, the initially more U-shaped profile (V/U = 0.81 ± 0.37) had turned into a pronounced V shape (V/U = 1.14 ± 0.21), whereas the control section retained its unaltered U shape (V/U = 0.62–0.75). This small-scale study on experimental of woody debris in sandy lowland streams showed that the negative impact of increased hydraulic disturbance of the existing streambed more than outweighed any positive impact resulting from the increase in woody debris. 相似文献
89.
Conservative solute tracer experiments were conducted in Indian Creek, a small urban stream located in Philadelphia, Pennsylvania, USA. Estimated flow rates were between 46 Ls(-1) and 81 Ls(-1), average stream width was 5.5m and average stream depth was 0.2m. Given these dimensions, most researchers would think it reasonable to assume that the stream is completely mixed vertically and horizontally. However, we found that the stream was not vertically completely mixed in a 1.0m deep, 30 m long pool. The limited mixing was demonstrated by the vertical stratification of a tracer cloud which was completely mixed both laterally and vertically across the stream prior to entering the pool. We suggest that the cause of limited mixing is due to a balance between groundwater inflow and transverse dispersion at the cross-section. We show that the unsupported assumption of complete mixing may result in a wide range, and thus increased uncertainty, of the values of stream flow and longitudinal dispersion coefficient estimated from these data. We conclude that the assumption of complete mixing and one-dimensional modeling must be checked against actual field conditions, even in small streams. 相似文献
90.
Understanding effects of flow alteration on stream biota is essential to developing ecologically sustainable water supply
strategies. We evaluated effects of altering flows via surface water withdrawals and instream reservoirs on stream fish assemblages,
and compared effects with other hypothesized drivers of species richness and assemblage composition. We sampled fishes during
three years in 28 streams used for municipal water supply in the Piedmont region of Georgia, U.S.A. Study sites had permitted
average withdrawal rates that ranged from < 0.05 to > 13 times the stream’s seven-day, ten-year recurrence low flow (7Q10),
and were located directly downstream either from a water supply reservoir or from a withdrawal taken from an unimpounded stream.
Ordination analysis of catch data showed a shift in assemblage composition at reservoir sites corresponding to dominance by
habitat generalist species. Richness of fluvial specialists averaged about 3 fewer species downstream from reservoirs, and
also declined as permitted withdrawal rate increased above about 0.5 to one 7Q10-equivalent of water. Reservoir presence and
withdrawal rate, along with drainage area, accounted for 70% of the among-site variance in fluvial specialist richness and
were better predictor variables than percent of the catchment in urban land use or average streambed sediment size. Increasing
withdrawal rate also increased the odds that a site’s Index of Biotic Integrity score fell below a regulatory threshold indicating
biological impairment. Estimates of reservoir and withdrawal effects on stream biota could be used in predictive landscape
models to support adaptive water supply planning intended to meet societal needs while conserving biological resources. 相似文献