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INCORPORATION OF DNA BARCODES INTO ASSESSMENTS OF THE BIOLOGICAL INTEGRITY OF AQUATIC ECOSYSTEMS: PRECISION, ACCURACY AND COST
Citation:
BAGLEY, M., C. SPOONER, R. KLAUDA, D. SCHINDEL, AND L. WEIGHT. INCORPORATION OF DNA BARCODES INTO ASSESSMENTS OF THE BIOLOGICAL INTEGRITY OF AQUATIC ECOSYSTEMS: PRECISION, ACCURACY AND COST. Presented at European Molecular Biology Organization Workshop, Rome, ITALY, May 17 - 19, 2007.
Impact/Purpose:
The objective of this task is to develop molecular indicators to evaluate the integrity and sustainability of aquatic fish, invertebrate, and plant communities (GPRA goal 4.5.2). Specifically, this subtask aims to evaluate methods for the measurement of:
fish and invertebrate community composition, especially for morphologically indistinct (cryptic) species
population genetic structure of aquatic indicator species and its relationship to landscape determinants of population structure (to aid in defining natural assessment units and to allow correlation of population substructure with regional stressor coverages)
genetic diversity within populations of aquatic indicator species, as an indicator of vulnerability to further exposure and as an indicator of cumulative exposure
patterns of temporal change in genetic diversity of aquatic indicator species, as a monitoring tool for establishing long-term population trends.
Description:
Historically, water quality assessments in the United States primarily focused on water chemistry assays at or near discharge sources. As it has become clear that waters also can be highly impaired from dispersed (i.e., non-point source) chemicals and non-chemical impacts, direct assays of the biological integrity of aquatic ecosystems were adopted as they reflect cumulative environmental impacts on biota. These "bioassessments" assess the incidence and abundance of fish and aquatic macroinvertebrates as indicators of aquatic ecosystem condition. Wider adoption of bioassessment protocols in governmental monitoring programs is desirable but constrained by three serious problems: (1) limited and declining taxonomic expertise for most taxa; (2) difficulty or inability to identify larval forms with high taxonomic resolution; and (3) low statistical confidence due to sample size limitations imposed by time and cost of morphological identifications. A possible solution to each of these problems is the integration of DNA barcoding into aquatic monitoring and assessment programs. We have initiated research to assess the accuracy, precision, and costs of taxonomic identifications for aquatic insects based on both DNA barcode and morphological approaches for a bioassessment program administered by the state of Maryland, USA. To directly compare DNA-based and morphological approaches, we are developing DNA barcodes for North Anerican Ephemeroptera (mayflies), Tricxhoptera (caddisflies), and Plecoptera (stoneflies), taxa which are important targets of stream bioasasessments because of their sensitivity to pollutants. A critical component of this research is the utilization of DNA barcodes to link morphologically cryptic aquatic larvae collected in streams to morphologically distinct adult voucher specimens maintained at the Smithsonian Institution. Based on our findings, we will recommend a strategy for optimal integration of DNA and morphological approaches into the state's bioassessment program that efficiently leverages available resources for specimen collection, taxonomic assessment, and data analysis. Incorporation of DNA sampling into bioassessment programs also may bring opportunities for more refined assays using population genetic models. As an example, I will show how archived DNA from bioassessments can be exploited to bring a systems understanding to aquatic ecosystem management, including identification of critical habitat necessary for metapopulation stability.