SS1.01 Assessing Potential Environmental Impacts of Aquaculture
Date: Thursday, June 13, 2002
Time: 10:15:00 AM
Location: Lecture Theatre
 
SotoD, Instituto de Acuicultura, Universidad Austral de Chile, Puerto Montt, Chile, dsoto@uach.cl
Norambuena, F, , Instituto de Acuicultura, Universidad Austral de Chile, Puerto Montt, Chile, fnorambuena@uach.cl
 
SALMON FARMING IMPACTS IN THE INNER SEAS OF SOUTHERN CHILE: IDENTIFYING ECOSYSTEM KEY- RESPONSE VARIABLES TO IMPLEMENT BETTER MANAGEMENT
image
Chile produced 300.000 tons of aquaculture salmon in 2001. Most salmon growth takes place in fjords and channels in floating pens. Such aquaculture activity supplies important amounts of C, N and P to the ecosystem with potential eutrophication consequences. We have been monitoring the water column and sediments of 43 farms, covering a wide scope of accumulated production. On each farm we also sampled a control site outside of the farm influence. We found little evidence of environmental impacts on water column nutrients, chlorophyll and phytoplankton but we found clear effects on the sediments, particularly on total N, P and the N/P ratio. From all these variables total phosphorus (P) showed the least variability among control sites within a wide array of environments and it was selected as the best indicator of salmon impact showing as well a good correlation with redox potential. We ranked the farms according to an index of P accumulation and use a multivariate approach to define the best predictors of P from the perspective of site conditions, farm management and ecosystemic processes.