2022 Early Hearing Detection & Intervention Virtual Conference

March 13 - 15, 2022

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5/21/2018  |   10:00 AM - 10:15 AM   |  URBAN BIOASSESSMENTS INDICATE INCREASED BENTHIC TOLERANCE   |  410 A

URBAN BIOASSESSMENTS INDICATE INCREASED BENTHIC TOLERANCE

Benthic macroinvertebrate tolerance values (TVs) are used to develop metrics for Benthic Indices of Biotic Integrity (B-IBIs), determine indicator taxa, or are aggregated to assess the overall tolerance of an assemblage based upon the relative abundance of individual taxa (Eg. HBI). These applications are particularly useful for regulatory agencies as surrogates for water quality if they are either incrementally correlated with the level of stress and/or have a threshold response (extirpation) when the amount of stress reaches some quantifiable level. However, few regulatory programs intensively monitor urban streams or have large numbers of sampling locations with elevated levels of anthropogenic stress. Benthic macroinvertebrate data from highly-urbanized Fairfax County, VA (2004-2016) were used to develop cumulative frequency distributions (CFDs) and generalized additive models (GAMs) for 74 genera and 57 families in response to urbanization (impervious area). The 95% and 75% percentile for both CFDs and GAMs were used in a novel approach to derive ‘urban’ tolerance values (TVs) for Mid-Atlantic Piedmont streams. The derived tolerances were compared to those used by regulatory agencies for Virginia & Maryland’s Piedmont physiographic provinces along with the Chesapeake Bay (Chessie B-IBI).

  • Urban
  • Biological Gradients & Thresholds
  • Invertebrate

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Presenters/Authors

Chris Ruck (), Fairfax County DPWES, Watershed Assessment Branch, christopher.ruck@fairfaxcounty.gov;


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Jonathan Witt (), Fairfax County Division of Stormwater Planning, jonathan.witt@fairfaxcounty.gov;


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LeAnne Astin (), Fairfax County Stormwater Planning, leanne.astin@fairfaxcounty.gov;


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