A Multi-tiered Approach for Biological Assessment of Urban Streams U.S. Department of the Interior U.S. Geological Survey

Transcription

1 A Multi-tiered Approach for Biological Assessment of Urban Streams U.S. Department of the Interior U.S. Geological Survey Donald H. Wilkison USGS Missouri Water Science Center Kansas City Office

2 Largely urban Inter-jurisdictional Intensely studied Blue River Basin

3 Urban streams have numerous stressors.

4 Approach. Health and diversity measures of: Aquatic macroinvertebrate communities Periphyton communities Land-use characterization Stream reach habitat assessments Water column chemistry Bottom sediment chemistry Tiered toxicity screenings of water and bottom sediments

5 Macroinvertebrates. Although better conditions in upstream reaches Aquatic Life Use Status: partially-supporting to non-supporting Conditions appear to be relatively stable

6 Macroinvertebrates Scores decline w/ urbanization. Gradients may not be as evident without high quality reference sites or large numbers of sites. (Poulton and others, 2007) Periphyton metric: Richness, diversity, trophic state, TotN optima, TotP optima, saprobic score, pollution tolerance, oxygen tolerance, nuisance algae, brackish, chloride, motility Algal.metric score.sum.of.15.metrics

7 Periphyton community structure Limited understanding/small data set (2009) Cluster analyses (non-metric multi-dimensional scaling) indicates shifts in community structure possible Variables (abiotic and/or biotic) are unlikely to be static

8 Aquatic health scores more strongly related to basin land use than local habitat Higher aquatic health scores related to lower concentrations of contaminants Landuse & chemistry are inter-related

9 ToTN, ToTP Sediment + bacteria Selected trace organic cmpds Caffeine, DEET, detergents, fecal sterols, triclosan, PAHs Stream chemistry LOADEST model (AMLE) development to establish: Annual loads Trends Establish environmentally relevant concentrations Aid contextualization of issues.

10 Annual loads-help describe removal efficiencies YEAR TotN, MT TotP, MT Caffeine, kg DEET, kg Triclosan, kg , WWTP-dominated stream , , , , , AVG. 1, , CSO-dominated stream AVG WWTP:CSO

11 Caffeine as surrogate for other micro-contaminants useful in describing boundary conditions

12 Define environmentally-relevant concentrations Concentration range may be narrow from micro-constituents Provide keys to other compounds of concern Outliers may represent acute boundaries

13 Episodic flushing of winter de-icing lasts for several months Elevated chloride conc. = increased road density & impervious cover Lower chloride conc. = lower road density & impervious cover

14 Sediment chemistry *Combined PAHs + Metals *Mean predicted toxicity from PEC-Q (39%)

15 Tiered toxicity screenings: Whole water (base-flow and storms) and sediments (2007) Primary producers: algae, Psuedokirchenella subcapita Consumers: crustacean, Daphnia magna Decomposers: bacteria,vibrio fischeri Benchtop methods using 3-5 replicates with controls Excessive nutrients induced growth in all AlgalTox samples Stormflow samples only occasionally exhibited toxicity to decomposers

16 Summary: Intensely studied Blue River Basin decreased aquatic diversity related to degraded habitats (physical and chemical) Urbanization plays a key, multi-tiered role Gradients may help to: establish attainability thresholds focus restoration efforts Models can help contextualize issues Chronic rather than acute toxicity more likely

17 Summary (cont.): Resilience of urban systems not well understood Blue River Basin changes 2 WWTP upgrades Long-term overflow control plan initiated Increased interest in non-point source controls Development pressures continue in the basin

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