HR: 09:15h
AN: NB21E-04    [Abstracts]
TI: Scientifically Derived Phosphorus Loading Objective and Adaptive Watershed Management for Lake Simcoe, Canada
AU: * Winter, J G
EM: jennifer.winter@ene.gov.on.ca
AF: Ontario Ministry of the Environment, Biomonitoring Section, 125 Resources Road, Toronto, ON M9P 3V6 Canada
AU: Walters, M
EM: m.walters@lsrca.on.ca
AF: Lake Simcoe Region Conservation Authority, 120 Bayview Parkway, Newmarket, ON L3Y 4X1 Canada
AU: Willox, C
EM: cam.willox@mnr.gov.on.ca
AF: Ontario Ministry of Natural Resources, Lake Simcoe Fisheries Assessment Unit, RR#2, Sutton West, ON L0E 1R0 Canada
AB: The recruitment failure of native cold-water fish in Lake Simcoe, Canada, has been attributed to a three-fold increase in phosphorus (P) loading from pre-settlement rates and consequent oxygen depletion in the hypolimnion and spawning shoal degradation. These water quality concerns led to a multi-agency partnership, the Lake Simcoe Environmental Management Strategy, whose goals include reducing phosphorus loading to the lake and restoring a self-sustaining cold-water fishery. A targeted end-of-summer hypolimnetic dissolved oxygen concentration (DO) was related to phosphorus loading rate through a series of intermediary relationships among trophic state variables using an empirical modeling approach to derive a phosphorus loading objective. The proposed P loading target of 75 metric tons/year is predicted to generate a P concentration of 0.01 mg/L and an end-of-summer hypolimnetic DO of 5 mg/L. The 5mg/L target is considered a significant interim step towards the goal of 7mg/L, a threshold above which cold-water fish recruitment should no longer be impaired. This model is presently being evaluated using data collected from 1980 to 2004 and will be compared to a three-dimensional mechanistic lake model. An adaptive watershed management approach is employed to meet the phosphorus loading target, linking scientific assessments to implementation activities and incorporating community education.
DE: 1845 Limnology
DE: 4239 Limnology
DE: 4842 Modeling
DE: 4845 Nutrients and nutrient cycling
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly