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21.
Exposures of caged organisms in situ have proven to be a useful way to improve exposure realism and link to stressor effects in aquatic assessments of hazard or risk. A novel cage system, the benthic in situ toxicity identification evaluation (BiTIE), was developed for benthic macroinvertebrates (surrogate species, resident populations and communities) to separate low and high flow effects, and major chemical classes of stressors in streams. Three resin types were used to separate the chemical stressors in the streams Honey Creek and Little Beavercreek, Ohio, USA: Dowex Optipore (non-polar organics), zeolite (ammonia), and polywool (control). Isonychia spp. sensitivity was compared to Chironomus tentans, and no significant differences were found (p>0.05). Isonychia spp. growth (length) showed a stressor response in the zeolite treatments, and community testing revealed improved metric responses in the Dowex treatments. The BiTIE chamber system demonstrated stressor-response relationships using sublethal and multimetric endpoints. 相似文献
22.
When native grassland catchments are converted to pasture, the main effects on stream physicochemistry are usually related
to increased nutrient concentrations and fine-sediment input. We predicted that increasing nutrient concentrations would produce
a subsidy-stress response (where several ecological metrics first increase and then decrease at higher concentrations) and
that increasing sediment cover of the streambed would produce a linear decline in stream health. We predicted that the net
effect of agricultural development, estimated as percentage pastoral land cover, would have a nonlinear subsidy-stress or
threshold pattern. In our suite of 21 New Zealand streams, epilithic algal biomass and invertebrate density and biomass were
higher in catchments with a higher proportion of pastoral land cover, responding mainly to increased nutrient concentration.
Invertebrate species richness had a linear, negative relationship with fine-sediment cover but was unrelated to nutrients
or pastoral land cover. In accord with our predictions, several invertebrate stream health metrics (Ephemeroptera–Plecoptera–Trichoptera
density and richness, New Zealand Macroinvertebrate Community Index, and percent abundance of noninsect taxa) had nonlinear
relationships with pastoral land cover and nutrients. Most invertebrate health metrics usually had linear negative relationships
with fine-sediment cover. In this region, stream health, as indicated by macroinvertebrates, primarily followed a subsidy-stress
pattern with increasing pastoral development; management of these streams should focus on limiting development beyond the
point where negative effects are seen. 相似文献
23.
Progress toward the goal of restoring integrity to the waters in the United States has been difficult to assess. This difficulty may arise from the type of regulatory policy that has been traditionally used. With the advent of widespread wastewater treatment, the use of a planning approach employing receiving water impact standards may offer a more practical and direct means of defining and assessing integrity. Biological community response is shown to offer an integrated approach to implementing and evaluating water quality management policy. The state of Maine (USA) has revised its water quality law by utilizing biological community response to assess integrity. This law is presented as a model that employs impact measures and a planning approach for the implementation of water quality management policy. 相似文献
24.
Monitoring of stream restoration projects is often limited and success often focuses on a single taxon (e.g., salmonids),
even though other aspects of stream structure and function may also respond to restoration activities. The Ottawa National
Forest (ONF), Michigan, conducted a site-specific trout habitat improvement to enhance the trout fishery in Cook’s Run, a
3rd-order stream that the ONF determined was negatively affected by past logging. Our objectives were to determine if the habitat
improvement increased trout abundances and enhanced other ecological variables (overall habitat quality, organic matter retention,
seston concentration, periphyton abundance, sediment organic matter content, and macroinvertebrate abundance and diversity)
following rehabilitation. The addition of skybooms (underbank cover structures) and k-dams (pool-creating structures) increased
the relative abundance of harvestable trout (>25 cm in total length) as intended but not overall trout abundances. Both rehabilitation
techniques also increased maximum channel depth and organic matter retention, but only k-dams increased overall habitat quality.
Neither approach significantly affected other ecological variables. The modest ecological response to this habitat improvement
likely occurred because the system was not severely degraded beforehand, and thus small, local changes in habitat did not
measurably affect most physical and ecological variables measured. However, increases in habitat volume and in organic matter
retention may enhance stream biota in the long term. 相似文献
25.
M.A. Beketov K. Foit C.A. Schriever E. Capri C. Wells 《Environmental pollution (Barking, Essex : 1987)》2009,157(6):1841-1848
To detect effects of pesticides on non-target freshwater organisms the Species at risk (SPEARpesticides) bioindicator based on biological traits was previously developed and successfully validated over different biogeographical regions of Europe using species-level data on stream invertebrates. Since many freshwater biomonitoring programmes have family-level taxonomic resolution we tested the applicability of SPEARpesticides with family-level biomonitoring data to indicate pesticide effects in streams (i.e. insecticide toxicity of pesticides). The study showed that the explanatory power of the family-level SPEAR(fm)pesticides is not significantly lower than the species-level index. The results suggest that the family-level SPEAR(fm)pesticides is a sensitive, cost-effective, and potentially European-wide bioindicator of pesticide contamination in flowing waters. Class boundaries for SPEARpesticides according to EU Water Framework Directive are defined to contribute to the assessment of ecological status of water bodies. 相似文献
26.
Megan MH Nash MS Neale AC Pitchford AM 《Environmental monitoring and assessment》2007,124(1-3):141-156
The objective of this study was to assess the applicability of using landscape variables in conjunction with water quality
and benthic data to efficiently estimate stream condition of select headwater streams in the Mid-Atlantic Coastal Plains.
Eighty-two streams with riffle sites were selected from eight-two independent watersheds across the region for sampling and
analyses. Clustering of the watersheds by landscape resulted in three distinct groups (forest, crop, and urban) which coincided
with watersheds dominant land cover or use. We used non-parametric analyses to test differences in benthos and water chemistry
between groups, and used regression analyses to evaluate responses of benthic communities to water chemistry within each of
the landscape groups. We found that typical water chemistry measures associated with urban runoff such as specific conductance
and dissolved chloride were significantly higher in the urban group. In the crop group, we found variables commonly associated
with farming such as nutrients and pesticides significantly greater than in the other two groups. Regression analyses demonstrated
that the numbers of tolerant and facultative macroinvertebrates increased significantly in forested watersheds with small
shifts in pollutants, while in human use dominated watersheds the intolerant macroinvertebrates were more sensitive to shifts
in chemicals present at lower concentrations. The results from this study suggest that landscape based clustering can be used
to link upstream landscape characteristics, water chemistry and biotic integrity in order to assess stream condition and likely
cause of degradation without the use of reference sites. Notice: Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency
policy. 相似文献
27.
Christophe Piscart Romuald Genoel Eric Chauvet 《Environmental pollution (Barking, Essex : 1987)》2009,157(3):1011-1018
In developed countries, changes in agriculture practices have greatly accelerated the degradation of the landscape and the functioning of adjacent aquatic ecosystems. Such alteration can in turn impair the services provided by aquatic ecosystems, namely the decomposition of organic matter, a key process in most small streams. To study this alteration, we recorded three measures of heterotrophic activity corresponding to microbial hydrolasic activity (FDA hydrolysis) and leaf litter breakdown rates with (kc) and without invertebrates (kf) along a gradient of contrasted agricultural pressures. Hydrolasic activity and kf reflect local/microhabitat conditions (i.e. nutrient concentrations and organic matter content of the sediment) but not land use while kc reflects land-use conditions. kc, which is positively correlated with the biomass of Gammaridae, significantly decreased with increasing agricultural pressure, contrary to the taxonomic richness and biomass of Trichoptera and Plecoptera. Gammaridae may thus be considered a key species for organic matter recycling in agriculture-impacted streams. 相似文献
28.
A range of macroinvertebrate indices were compared to assess the most appropriate metric for the assessment of acid mine drainage (AMD) in a low alkalinity, highly erosional river in south-east Ireland. Differences were found in the ability of indices to discriminate AMD impact with the Brillouin, BMWP score, Margalef and Shannon Indices the most precise. Taxon richness was also strongly correlated with AMD indicator parameters (e.g. pH alkalinity, sulphate, Zn and Fe) at impacted sites being an equally reliable metric. The response of the community structure to AMD in this river does not fulfil the optimum criteria for either diversity or biological indices, which may explain the variation in the success of different indices seen in this and other studies. The development of indices that model the expected community response to AMD more accurately or are based on the response of indicator species to AMD pollutants are required. 相似文献
29.
The choice of spatial and temporal scale used in environmental assessments may influence the observed results. One method
of assessing the impact of stream habitat alterations involves the comparison of response variables among treatment categories
(i.e., impacted and unimpacted sites). The influence of spatial resolution on patterns of response variables among treatment
categories in assessments of stream channelization and other types of habitat alterations has not been evaluated. We examined
how patterns of 10 community response variables among channel types and our interpretations of channelization impacts on fish
and macroinvertebrate communities differed among three spatial resolutions in a warmwater stream in Mississippi and Alabama.
Four fish and three macroinvertebrate community response variables exhibited different patterns among channel types at different
spatial resolutions. Our interpretations of the impacts of channelization on fish and macroinvertebrate communities differed
among spatial resolutions. Channelization had a negative influence on fish communities either with or without evidence of
potential community recovery in one channel type. Channelization impacts on macroinvertebrate communities ranged from a negative
influence to no effect. Our results suggest that spatial resolution can influence the observed results and interpretations
derived from assessments of stream habitat alterations. 相似文献
30.
Vondracek B Blann KL Cox CB Nerbonne JF Mumford KG Nerbonne BA Sovell LA Zimmerman JK 《Environmental management》2005,36(6):775-791
We synthesized nine studies that examined the influence of land use at different spatial scales in structuring biotic assemblages
and stream channel characteristics in southeastern Minnesota streams. Recent studies have disagreed about the relative importance
of catchment versus local characteristics in explaining variation in fish assemblages. Our synthesis indicates that both riparian-
and catchment-scale land use explained significant variation in water quality, channel morphology, and fish distribution and
density. Fish and macroinvertebrate assemblages can be positively affected by increasing the extent of perennial riparian
and upland vegetation. Our synthesis is robust; more than 425 stream reaches were examined in an area that includes a portion
of three ecoregions. Fishes ranged from coldwater to warmwater adapted. We suggest that efforts to rehabilitate stream system
form and function over the long term should focus on increasing perennial vegetation in both riparian areas and uplands and
on managing vegetation in large, contiguous blocks.
Minnesota Cooperative Fish and Wildlife Research Unit is jointly sponsered by U.S. Geological Survey Biological Resources
Division, the University of Minnesota, The Minnesota Department of Natural Resources, and the Wildlife Management Institute. 相似文献