An evaluation of artificial substrates for monitoring the quagga mussel (Dreissena bugensis) in Lake Mead, Nevada–Arizona

Abstract

This experiment was conducted to determine if quagga mussels (Dreissena bugensis) settle and grow on different types of artificial substrates preferentially in Lake Mead, Nevada–Arizona, one of the first known populations of the mussel in the western United States. Six substrates, acrylonitrile butadiene styrene (ABS) plastic, high density polyethylene (HDPE) plastic, concrete underlayment board (CUB), aluminum, stainless steel and fiberglass were cut into 10 cm squares and placed at different depths in the Boulder Basin of Lake Mead for approximately 1 yr in a modified randomized block design. Half the substrates were removed and replaced every 2 mo, and the other half remained in the water for the duration of the study. No preference for substrate type could be determined, but settlement was limited by depth. Mussel settlement on substrates at depths from 6–28 m was significantly greater than on substrates from 32–54 m (F = 5.54; p < 0.001). This divergence in settlement at different depths is likely due to the water quality characteristics at these depths. No relationship was found between mussel settlement on substrates and veliger concentrations in the water column. Mussel settlement was limited when the lake was destratified between January and March 2009. Based on this experiment, materials placed in Lake Mead below 32 m will have greatly reduced mussel settlement, especially if deployed when the lake is destratified.