SS1.01 Assessing Potential Environmental Impacts of Aquaculture
Date: Thursday, June 13, 2002
Time: 11:00:00 AM
Location: Lecture Theatre
 
ReidGK, University of Guelph, Aquaculture Centre, Department of Animal & Poultry Science, Guelph, ON, Canada, gregor@uoguelph.ca
Moccia, R, D, University of Gulph, Aquaculture Centre, Department of Animal & Poultry Science, Guelph, ON, Canada, rmoccia@uoguelph.ca
 
Variation in Total Phosphorus Concentrations at a Freshwater Cage-Aquaculture Site and Insights into Improving Water Quality Monitoring Protocols
image
Effective sampling methods to assess water quality impacts from net pen aquaculture must account for both the temporal and spatial variations of water quality parameters, and these can be either natural or related to nutrient outputs from the farm itself. To develop such methods, the variations of total phosphorus in the effluent of cultured rainbow trout in a laboratory and the near-field water (<30m distant) of a commercial freshwater cage-site in Lake Huron were compared. Under typical stocking densities and feeding regimens, the total phosphorus (TP) concentration varied diurnally more than three fold in both the tank effluent samples (10-31 ppb) and at the commercial lake Huron site (6 -24 ppb). While there was some predictability of daily TP fluctuations in the lab, forecasting of these diurnal fluctuations at the commercial site was not possible. The seasonal trends in near-field TP concentrations were reflective of changes in nutrient loading as estimated by a bioenergetic growth model. Suggestions for improving the effectiveness of water quality monitoring protocols at cage-aquaculture sites are discussed.