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Skovlund G Damgaard C Bayley M Holmstrup M 《Environmental pollution (Barking, Essex : 1987)》2006,144(3):808-815
The ability of Collembola to survive drought stress is crucial for their distribution in the terrestrial environment. Previous studies have suggested that several toxic compounds affect the drought tolerance of Folsomia candida in a synergistic manner and that these compounds have the feature in common that they elicit their toxicity by causing membrane damage. We hypothesised that the detrimental effect of toxic chemicals on drought tolerance in F. candida depends on the lipophilicity (log K(ow)) of the compound because a higher log K(ow) would mean a closer interaction with membranes. In this study the three chemicals 4-nonylphenol, pyrene and p,p'-DDE were tested. Surprisingly, 4-nonylphenol, with the lowest log K(ow), was the most potent with respect to reducing drought tolerance followed by pyrene, suggesting that interactions between drought tolerance and chemical stress do not depend on lipophilicity alone. 相似文献
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Some of the principal controlling factors affecting the Everglades marsh system were combined in a simple model including growth of grass, water levels, rain, transpiration, peat deposition, fire and phosphorus and controlled inflow of water containing nutrients. Using data from published sources, coefficients were estimated and the model was simulated for several regimes, for varying concentrations of nutrient in the inflows and for varying access to fire. The resulting graphs resemble patterns reported from the Everglades, with some regimes producing regular repeating patterns and frequent small fires, whereas other regimes produced erratic and widely fluctuating patterns of vegetation, flood and fire. High phosphorus increased water loss by affecting plant transpiration: oscillations of vegetation and fire caused nutrient oscillations. Inflow of low nutrient water decreased nutrient levels by binding nutrients in plant masses. Continuous high water levels developed large accumulations of vegetation and peat, binding the nutrients, making larger fires when water levels were lowered. If this model is pertinent, a regular period of variation of water inflow and limited nutrients may be means for management of marshes for long range stability. 相似文献
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We developed and tested a plant-based index of biological integrity (IBI) and used it to evaluate the existing reclamation
wetlands in Alberta’s oil sands mining region. Reclamation plans call for >15,000 ha of wetlands to be constructed, but currently,
only about 25 wetlands are of suitable age for evaluation. Reclamation wetlands are typically of the shallow open water type
and range from fresh to sub-saline. Tailings-contaminated wetlands in particular may have problems with hydrocarbon- and salt-related
toxicity. From 60 initial candidate metrics in the submersed aquatic and floating vegetation communities, we selected five
to quantify biological integrity. The IBI included two diversity-based metrics: the species richness of floating vegetation
and the percent of total richness contributed by Potamogeton spp. It also included three relative abundance-based metrics: that of Ceratophyllum demersum, of floating leafed species and of alkali-tolerant species. We evaluated the contribution of nonlinear metrics to IBI performance
but concluded that the correlation between IBI scores and wetland condition was not improved. The method used to score metrics
had an influence on the IBI sensitivity. We conclude that continuous scoring relative to the distribution of values found
in reference sites was superior. This scoring approach provided good sensitivity and resolution and was grounded in reference
condition theory. Based on these IBI scores, both tailings-contaminated and tailings-free reclamation wetlands have significantly
lower average biological integrity than reference wetlands (ANOVA: F
2,59 = 34.7, p = 0.000000000107). 相似文献
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Disturbance and recovery of large floodplain rivers 总被引:7,自引:0,他引:7
Richard E. Sparks Peter B. Bayley Steven L. Kohler Lewis L. Osborne 《Environmental management》1990,14(5):699-709
Disturbance in a river-floodplain system is defined as an unpredictable event that disrupts structure or function at the ecosystem,
community, or population level. Disturbance can result in species replacements or losses, or shifts of ecosystems from one
persistent condition to another. A disturbance can be a discrete event or a graded change in a controlling factor that eventually
exceeds a critical threshold.
The annual flood is the major driving variable that facilitates lateral exchanges of nutrients, organic matter, and organisms.
The annual flood is not normally considered a disturbance unless its timing or magnitude is “atypical.” The record flood of
1973 had little effect on the biota at a long-term study site on the Mississippi River, but the absence of a flood during
the 1976–1977 Midwestern drought caused short- and long-term changes. Body burdens of contaminants increased temporarily in
key species, because of increased concentration resulting from reduced dilution. Reduced runoff and sediment input improved
light penetration and increased the depth at which aquatic macrophytes could grow. Developing plant beds exerted a high degree
of biotic control and were able to persist, despite the resumption of normal floods and turbidity in subsequent years.
In contrast to the discrete event that disturbed the Mississippi River, a major confluent, the Illinois River, has been degraded
by a gradual increase in sediment input and sediment resuspension. From 1958 to 1961 formerly productive backwaters and lakes
along a 320-km reach of the Illinois River changed from clear, vegetated areas to turbid, barren basins. The change to a system
largely controlled by abiotic factors was rapid and the degraded condition persists.
Traditional approaches to experimental design are poorly suited for detecting control mechanisms and for determining the critical
thresholds in large river-floodplains. Large river-floodplain systems cannot be manipulated or sampled as easily as small
streams, and greater use should be made of man-made or natural disturbances and environmental restoration as opportunistic
experiments to measure thresholds and monitor the recovery process.
Coauthors are listed in alphabetical order. 相似文献
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Damgaard CHRISTIAN Hojer RIKKE Bayley MARK Scott-Fordsmand JANECK J. Holmstrup MARTIN 《Environmental and Ecological Statistics》2002,9(2):195-200
A method is presented for modeling the effect of two stresses on mortality. The model assumes a multiplicative simple two-parameter dose-response curve relationship between mortality and the two factors as well as for the effect of combining the two factors. The dose-response curve is modified in order to model survival probabilities. It is shown that the model adequately describes mortality data of Folsomia candida (Collembola) in a two-stress factor design. 相似文献
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Restoration of a Canadian Prairie Wetland with Agricultural and Municipal Wastewater 总被引:1,自引:0,他引:1
3 /day (800,000 US gallons) of municipal wastewater and beef processing wastewater. A large nongovernmental organization hastened
restoration with a development process that outlined restoration goals and management objectives to satisfy a dual mandate
of wastewater treatment and wildlife habitat creation. In 1995, after five years of wastewater additions, the basins had been
refilled and the surrounding uplands had been acquired and restored. The Frank Lake Conservation Area currently provides high-quality
habitat for a variety of wildlife in a region where many of the native plants and animals species have been lost due to habitat
loss and fragmentation. The success of upland and water management strategies is reflected in the increase of target species'
abundance and richness: 50 shorebird species, 44 waterfowl species, 15 raptor species, and 28 other new bird species have
returned to the marsh since restoration. As well, significant N and P reduction occurs as waters flow through the first basin
of the marsh. The management strategies of this project that satisfied a dual mandate serve as a model to guide managers of
other large-scale wetland restoration projects. 相似文献
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