HR: 16:15h
AN: NB14D-04 INVITED     [Abstracts]
TI: A new approach for defining reference conditions in streams
AU: Kilgour, B
EM: bkilgour@jacqueswhitford.com
AF: Ontario Ministry of Natural Resources, Glenora Fisheries Station RR 4,, Picton, Ont K0K 2T0 Canada
AU: * Stanfield, L
EM: Les.Stanfield@mnr.gov.on.ca
AF: Jacques Whitford Environment Limited, 2781 Lancaster Road, Ottawa, ON K1B 1A7 Canada
AB: Assessments of stream fish or benthic communities normally involve a contrast of conditions at "test" sites to conditions represented by "regional"-reference sites that are either pristine or "least"-impaired. Identification of reference sites is difficult and normally involves a variety of subjective criteria. The development of reference models for stream fish and benthos in southern Ontario is particularly challenging because there are few undeveloped areas and there is no consensus on criteria for least impaired condition. Rather than identify sites as representing a least-impaired condition, we have developed a series of models that relate the existing biophysical condition of streams (i.e., the fish, benthos and instream habitat) to landscape (i.e., slope, geology, catchment area) and landcover (% imperviousness). Relationships between indices of biophysical condition and imperviousness can be used to "hindcast" or estimate the expected biophysical condition at a variety of imperviousness scenarios. The models cannot be used to predict conditions outside the calibration data range, but this approach does allow us to make use of an impairment gradient, and make predictions with a minimal number of least-impaired sites. The difference between the hindcast reference and present day conditions is an estimate of the present-day impacts.
DE: 0400 Biogeosciences
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly