An Annular Chamber for Aquatic Animal Preference Studies

Preference chambers are widely used to measure the responses of aquatic organisms to different environmental gradients, such as temperature, salinity, and pollutants. Most of the preference chambers used to date have been handicapped by the presence of one or more confounding variables, including differential light intensities and water depths and the presence of cover. We present a design and test results for an annular preference chamber with uniform environment water depth, light intensity, and cover. Preliminary testing with juvenile anadromous rainbow trout Oncorhynchus mykissshowed that they selected temperatures (±SE) of 18.1 ± 0.3°C, a result that compares favorably with values reported in the literature. We demonstrate that the annular chamber is a viable alternative to the more traditional horizontal, vertical, or shuttlebox-type designs for preference studies of aquatic organisms.