5 research outputs found

    Larva and pupa of Cernotina spicata

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    The first positively associated larva and pupa of Cernotina are described. Tentative diagnoses are provided for distinguishing them from those of other genera of Nearctic Polycentropodidae, especially Polycentropus s. lat., which Cernotina most strongly resembles

    Benthic Macroinvertebrate Fauna in Small Streams Used by Cattle in the Blue Ridge Mountains, Virginia

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    Cattle production is a common land use, and the adverse effects of cattle grazing on stream habitat and macroinvertebrates has been well docu-mented. The purpose of our study was to provide a list of taxa that can be expected to occur in small streams impacted by cattle in the southern Blue Ridge Mountains and to demonstrate how taxon-specific natural history information can be used to gain insight about benthic habitat condition. We identified 97 benthic macroinvertebrate taxa from five cattle-impacted streams that differed in cattle grazing intensity. Our findings suggest that some macroinvertebrate taxa can sustain low levels of cattle grazing and that sedimentation is a major stressor to the macroinvertebrate fauna

    Environmental factors accounting for benthic macroinvertebrate assemblage structure at the sample scale in streams subjected to a gradient of cattle grazing

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    Macroinvertebrate assemblages were related to environmental factors that were quantified at the sample scale in streams subjected to a gradient of cattle grazing. Environmental factors and macroinvertebrates were concurrently collected so assemblage structure could be directly related to environmental factors and the relative importance of stressors associated with cattle grazing in structuring assemblages could be assessed. Based on multivariate and inferential statistics, measures of physical habitat (% fines and substrate homogeneity) had the strongest relationships with macroinvertebrate assemblage structure. Detrital food variables (coarse benthic and fine benthic organic matter) were also associated with assemblage structure, but the relationships were never as strong as those with physical habitat measures, while autochthonous food variables (chlorophyll a and epilithic biomass) appeared to have no association with assemblage structure. The amount of variation explained in taxa composition and macroinvertebrate metrics is within values reported from studies that have examined macroinvertebrate metric–sediment relationships. The % Coleoptera and % crawlers had consistent relationships with % fines during this study, which suggests they may be useful metrics when sediment is a suspected stressor to macroinvertebrate assemblages in Blue Ridge streams. Findings from this study also demonstrate the importance of quantitative sampling through time when research goals are to identify relationships between macroinvertebrates and environmental factors
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