A BIOASSESSMENT STUDY OF LITTLE HUNTING CREEK TO DETERMINE POSSIBLE IMPACT OF FISH FARM DISCHARGES ON THE STREAM ENVIRONMENT

Abstract

A bioassessment was performed on a first order Maryland trout stream to determine the impact of effluent discharges from a pond based aquaculture production facility on the receiving water environment. Sample stations were established to bracket and isolate the discharge points of the pond discharges into the stream environment. Stream temperatures were recorded for eight months to examine the possibility of thermal warming caused by pond discharges into the stream. Published rapid bioassessment protocols were modified and used to evaluate stream habitat quality, benthic macroinvertebrate populations and fish populations. Air temperatures and riparian shade cover were found to strongly correlate with stream temperatures. No effect of pond discharges on stream temperature was demonstrated. Movement downstream produced a general reduction in habitat quality and was associated with declines in macroinvertebrate and fish population biological integrity rankings and metric scores when compared with reference environment conditions upstream. Declines occurred within station intervals irrespective of the presence or location of fish farm discharge points.