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Evaluating Urban Pesticide Toxicity to Macroinvertebrates

Study on impact of pesticides in urban stream water on aquatic organisms. Analyzing Pesticide Toxicity Index variations with urbanization, factors influencing it, and correlation with stream biota response. Conclusions on significance and future research needs.

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Evaluating Urban Pesticide Toxicity to Macroinvertebrates

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  1. Pesticides in urban settings – Use of a Pesticide Toxicity Index to evaluate potential toxicity of stream water samples to macroinvertebrates by Karen Riva-Murray, Patrick J. Phillips, Robert W. Bode, and Mark D. Munn

  2. What we know about modern-day pesticides: • Commonly applied in urban settings • Detected in stream water • Large spatial and temporal variation • Tend to occur as complex mixtures • Have a wide range of toxicities to aquatic organisms

  3. don’t What we ^ know: • Combined toxicity of the entire pesticide mixture • Response of stream biota • Factors affecting potential toxicity

  4. Pesticide Toxicity Index (PTI) Munn, M.D. and Gilliom, R.J., 2001, Pesticide Toxicity Index for freshwater aquatic organisms: U.S. Geological Survey Water-Resources Investigations Report 01-4077, 61 p.

  5. Objectives: • How does PTI vary in relation to urbanization? • What other factors influence PTI in urban settings? • Does change in PTI correspond with change in biological indicators?

  6. PTI Cautions and Caveats : • Use for relative rankings - not actual ‘toxicity’ • Bioassays done on limited taxa • Toxicities not available for all pesticides • Pesticides may not be included in lab analyses • Synergistic effects not accounted for

  7. Study Area – Croton watershed NYC water supply 47 sites small streams range of urban

  8. Methods- Water samples: All sites: Base-flow summer 2000 Kisco R. site: 2-4X/month & storms 2000-03 Macroinvertebrates: Baseflow summer 2000

  9. non-impacted slightly impacted moderately impacted Results – Bioassessment index versus urban intensity

  10. .1 .01 .001 .0001 .00001 .000001 .0000001 People per square mile Results – PTI versus urban intensity indicator PTI score + 10-8 .00000001

  11. Results – Similar to other urban areas Source – NAWQA summary reports

  12. non-impacted slightly impacted moderately impacted Results – Bioassessment versus PTI score

  13. PTI varies with season and with flow Results – Temporal variation; Kisco R. May 01-Sept 03

  14. Pesticide Toxicity Index Pesticide concentrations, April-Sept 2001-03 | 2000 | 2001 | 2002 | 2003 | Results – PTI does not track total concentration

  15. Conclusions: • PTI is a useful tool for evaluating the effects of urbanization on Water Quality • More information is needed • - Toxicities of newer pesticides • - Long-term trends in toxicity • - Synergistic effects • Relative PTI likely to increase with further urbanization • Pesticide toxicity may be an important contributing factor to decline in aquatic biological health in urban streams

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