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EVALUATING MACROINVERTEBRATE COMMUNITY RESPONSES TO IMPERVIOUS COVER IN CALIFORNIA WITH THRESHOLD INDICATOR TAXA ANALYSIS
Citation:
Figary, S. AND N. Detenbeck. EVALUATING MACROINVERTEBRATE COMMUNITY RESPONSES TO IMPERVIOUS COVER IN CALIFORNIA WITH THRESHOLD INDICATOR TAXA ANALYSIS. Society for Freshwater Science (SFS), Raleigh, North Carolina, June 04 - 08, 2017.
Impact/Purpose:
This presentation for the Society for Freshwater Scientists will discuss initial evaluation of community and taxa-specific thresholds of impairment for macroinvertebrates in California streams along a gradient of imperviousness. These analyses provide background information for selecting sites to evaluate green infrastructure BMP effectivess along a gradient of treated impervious cover. The identification of thresholds at very low levels of impervious cover, combined with narrow confidence limits for taxa thresholds, suggests that we should be able to detect moderation of development effects through post-BMP monitoring and comparison of pre-BMP response curves.
Description:
Since 2010, new construction in California is required to include stormwater detention and infiltration that is designed to capture rainfall from the 85th percentile of storm events in the region, preferably through green infrastructure. This study used recent macroinvertebrate community monitoring data to determine the ecological threshold for percent impervious cover prior to large scale adoption of green infrastructure using Threshold Indicator Taxa Analysis (TITAN). TITAN uses an environmental gradient and biological community data to determine individual taxa change points with respect to changes in taxa abundance and frequency across that gradient. Individual taxa change points are then aggregated to calculate the ecological threshold. This study used impervious cover data from National Land Cover Datasets and macroinvertebrate community data from California Environmental Data Exchange Network and Southern California Coastal Water Research Project. Preliminary TITAN runs for California’s Chaparral region indicated that both increasing and decreasing taxa had ecological thresholds of <1% watershed impervious cover. Next, TITAN will be used to determine shifts in the ecological threshold after the implementation of green infrastructure on a large scale.