Award Date


Degree Type


Degree Name

Master of Public Health (MPH)


Environmental and Occupational Health

First Committee Member

Shawn Gerstenberger

Second Committee Member

David Wong

Third Committee Member

Timothy Bungum

Fourth Committee Member

Craig Palmer

Fifth Committee Member

Michael Nichol

Number of Pages



In 2007, quagga mussels (Dreissena rostriformis bugensis) were found in Lake Mead and have spread downstream on the Colorado River and to other lakes and reservoirs in the Southwestern United States. The quagga mussel's extremely quick colonization of Lake Mead and annual veliger abundance trends provide evidence that the quagga mussels in the Southwest have different reproductive behavior than in previous habitats. This study is one of the first to specifically examine quagga mussel reproduction in the Southwest and examines how quagga mussel reproduction varies at sites known to have different temperatures and other environmental variables resulting from the input of Las Vegas Wash, and at different depths at each of these sites. Mussels were collected monthly over the course of a year at four different sites from Las Vegas Bay to Boulder Basin at depths of 20ft, 40ft and 70ft. A histological analysis of the gonads of these mussels was conducted to determine the reproductive development status in the form of a maturity index. This maturity index was then compared to environmental variables including water temperature, depth, water salinity, and dissolved oxygen. Out of these factors, temperature was the only environmental variable which showed a significant effect upon quagga mussel reproduction. Also the seasonal pattern of maturity indices was found to differ between the deepest and shallowest depths. This study contributes to the understanding of the reproductive biology of quagga mussels living in the southwestern United States.


Dreissena bugensis; Introduced aquatic organisms; Lake Mead; North America – Colorado River; Quagga mussel; Reproduction; Spawning; United States – Lake Mead


Aquaculture and Fisheries | Biology | Environmental Sciences