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    Author(s): A. Dennis Lemly; Ryan S. King
    Date: 2000
    Source: Wetlands. 20(1): 91-100.
    Publication Series: Miscellaneous Publication
    PDF: View PDF  (204 B)


    Field and laboratory studies were conducted to evaluate the use of bacterial growth on aquatic insects as a metric for determining the existence of nutrient impacts in wetlands. Results from field investigations indicated that elevated concentrations of nitrate and phosphate were associated with growth of filamentous bacteria on insect body surfaces and that there were significantly fewer mayflies (Ephemeroptera) in the nutrient-enriched wetland. Laboratory investigations confirmed a strong linkage between bacterial growth and reduced survival of mayflies. Survival was examined for individuals with bacterial infestation ranging from 0 percent to 60 percent body coverage. A threshold for catastrophic mortality was present at about the 25 percent level of coverage; there were very few survivors above that level. Based on these findings, the diagnostic endpoint for the bioindicator is 25 percent body coverage by bacterial growth, a level that signifies major differences in insect populations in the field and is also easy to detect visually. This study provides evidence that the insect-bacteria bioindicator is a reliable tool for assessing nutrient impacts on wetland macroinvertebrate communities. The bioindicator could be useful in the development of a Wetland Bioassessment Protocol.

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    Lemly, A. Dennis; King, Ryan S. 2000. An insect-bacteria bioindicator for assessing detrimental nutrient enrichment in wetlands. Wetlands. 20(1): 91-100.

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