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Nutrient-Biota Interactions in Agricultural Landscapes: Lessons from USGS NAWQA Program

Explore the effects of nutrient enrichment on stream ecosystems, biological communities, nitrogen cycling, and nutrient ratios in different environmental settings. Discover the implications for nutrient criteria and habitat limitations in agricultural streams.

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Nutrient-Biota Interactions in Agricultural Landscapes: Lessons from USGS NAWQA Program

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  1. Nutrient-Biota Interactions in Agriculturally Dominated Landscapes: Lessons from the USGS National Water-Quality Assessment (NAWQA) Program Mark D. Munn NAWQA Nutrient Effects Team Leader USGS Washington Water Science Center Tacoma, WA

  2. Nutrient Enrichment Effects on Stream Ecosystems Determine how biological communities and processes respond to varying levels of nutrient enrichment in streams from contrasting environmental settings. • Biological communities: nutrients, habitat, algae and invertebrates • Stream metabolism: dissolved oxygen production • Nitrogen cycling: transport, transformations, uptake

  3. Delaware Washington Indiana Nebraska Georgia

  4. Chlorophyll a* Algal AFDW Community composition Community metrics Production/respiration Secondary production pH DO Hydrologic studies Nitrogen* Phosphorus* Nutrient ratios Sediment composition Temperature Transparency/TSS* EPA Nutrient Indicators Chlorophyll a [rock/wood, silt/sand, or seston]

  5. Nutrient Gradient – Response Conceptual Model eutrophic Threshold BIOLOGICAL RESPONSE oligotrophic NUTRIENT GRADIENT

  6. IN and NE exceeded TP threshold

  7. All study units exceeded nitrogen threshold

  8. TN exceeded proposed EPA criteria at 76 to 96% of sites Proposed EPA Nutrient Criteria 1.5 0.7 0.38 0.88 2.18 0.69 0.71 76% 96% 87% 83% 96%

  9. TP exceeded proposed EPA criteria at 52 to 100% of sites Proposed EPA Nutrient Criteria 0.022 0.067 0.076 0.037 0.031 93% 100% 67% 52% 89%

  10. Seston CHLa exceeded proposed EPA criteria at 11 to 93% of sites Proposed EPA Nutrient Criteria 10 1.78 3 2.7 0.93 3.75 41% 93% 11% 32% 28%

  11. Chlorophyll a varied by substrate

  12. National TP-CHLa relationship exists, … r2 = 0.11

  13. …but distinct regional differences.

  14. Seston CHLa vs TP and TN in GA SESTON CHLOROPHYLL A (ug/L) SESTON CHLOROPHYLL A (ug/L) .04 0.01 0.1 0.1 TN (mg/L) TP (mg/L)

  15. Habitat limits CHLa Spearman (rs) correlation matrix (N=142) BFI = Base Flow Index, the ratio of base flow to total flow volume for a given year.

  16. Algae control nutrients -low nutrients due to uptake Nutrient saturation - possible physical controls eutrophic CHLOROPHYLL A Nutrients control algae - nutrient limitation Algae limited by physical processes - stream flow, light, sediment, etc. oligotrophic NUTRIENT CONCENTRATION

  17. Implications for Nutrient Criteria • Nutrient concentrations and chlorophyll may not always provide the best indication of stream status. • Agricultural streams can be nutrient saturated and habitat limited. • Need sub-regional and/or stream-type specific predictive models that incorporate nutrients, habitat, and biological components.

  18. Contact Information Mark D. Munn Washington Water Science Center U.S. Geological Survey Tacoma, WA 98402 253-428-3600 x2686 mdmunn@usgs.gov National NAWQA: http://water.usgs.gov/nawqa/ Nutrient Effects Team: http://pubs.usgs.gov/fs/fs11803/

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