SS1.01 Assessing Potential Environmental Impacts of Aquaculture
Date: Thursday, June 13, 2002
Time: 3:15:00 PM
Location: Lecture Theatre
 
BrooksKM, Aquatic Environmental Sciences, Port Townsend, USA, brooks@olympus.net
 
RELATIONSHIP BETWEEN SEDIMENT CONCENTRATIONS OF FREE SULFIDES AND MACROBENTHIC COMMUNITY RESPONSE
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Studies were undertaken at seven salmon farms in British Columbia during 2000 to determine the usefulness of sediment concentrations of free sulfides, redox potential and loss on ignition as indicators of biological response to organic enrichment. Chemical and biological effects in sediments were highly correlated with free sulfides and redox potential and extended to distances of 205 meters from the cages. Loss on ignition was shown to be an inappropriate endpoint for evaluating biological response. Concentrations of free sediment sulfides were most predictive. Species diversity declined with increasing sulfides without a lower no-effects concentration. The abundance of macrofauna was enhanced by at least eight opportunistic species of arthropods and annelids between 200 and 4,750 micromoles sulfide. Sediments were generally, but not always, depauperate at sulfide concentrations greater than 8,000 micromoles. Ranges of sulfide tolerance were defined for 85 of the more common taxa. The study clearly demonstrated the usefulness of sediment free sulfides for predicting the biological response to benthic enrichment.