8280

• UCREFRP Catalog Number: 8280
• Author: Beyers, D. W. and C. Sodergren.
• Title: Assessment of Exposure of Larval Razorback Sucker to Selenium in Natural Waters and Evalutaion of Laboratory-Based Predictions.
• USFW Year: 2001.
• USFW - Doc Type: Fort Collins, CO.
• Copyright Material: NO

Fathead minnow
Larval fathead minnow were purchased from Aquatic BioSystems Inc. (Fort Collins,
Colorado). Experimental animals were acclimated to test temperature and water quality for
48 hours before toxicity tests were initiated. Larvae were approximately 3-days old at the start of
' acute tests.
Experimental design and exposure system for ELS tests
Experimental treatments were assigned to replicate exposure beakers (n=4) using a
randomized, balanced 5X2 factorial design. The first factor, selenium exposure, had five levels
of dissolved and corresponding dietary concentrations (control, 25, 50, 100, and 200 µg/L). The
second factor, species, had two levels (razorback sucker and flannelmouth sucker).
Exposure procedures were based on prescribed methods for conducting ELS toxicity tests
with fishes (ASTM 1990a). Ten larvae were assigned to each exposure beaker (experimental
unit). Beakers were polyethylene vessels having a diameter of 12 cm and height of 15 cm.
Depth of test solutions was 9.5 cm. A continuous-flow diluter was used to generate exposure
concentrations. The diluter maintained a 0.5 dilution factor and supplied a volume of 34 ml/min
to exposure beakers. Larvae were transferred from mass cultures to flow-through beakers about
24 h before the toxicant metering system was activated. Cool-white fluorescent lamps were the
only source of illumination (5301x), and a 12:12-h light:dark photoperiod was maintained.
Larvae in each beaker of each experimental treatment were offered the same daily ration
of living rotifers. The average daily ration was equivalent to 914 rotifers per fish. Survival of
fish in each treatment was monitored daily. Growth was quantified at the end of the 28-d
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