Award Date

12-1-2012

Degree Type

Thesis

Degree Name

Master of Public Health (MPH)

Department

Environmental Science

First Committee Member

David Wong

Second Committee Member

Shawn Gerstenberger

Third Committee Member

Mark Buttner

Fourth Committee Member

Jacimaria Batista

Number of Pages

127

Abstract

The non-native quagga mussel [Dreissena bugensis (Andrusov, 1897)] was initially discovered in Boulder Basin of Lake Mead, Nevada-Arizona on January 6, 2007. This occurrence marked the first biological invasion of dreissenid mussels in the Western U.S., following a significant North American range expansion of invasive quagga mussels from populations that invaded and colonized the Great Lakes Region in the Northeastern U.S. during 1991. This nonindigenous mollusk species quickly spread from Boulder Basin and became established throughout the entire reservoir by the end of 2007, with the exception of the inner Las Vegas Bay. There was an apparent absence of settled juvenile and adult life forms, in spite of the fact that embryonic veligers were abundant in Las Vegas Bay in early 2009. It is theorized that this phenomenon may be attributable to the elevated inorganic nutrient loading to Las Vegas Bay from treated wastewater effluent released to Las Vegas Wash by the municipal wastewater treatment plants, and the pollutants that are carried in stormwater runoff from the Las Vegas Valley to the inner bay. The Southern Nevada Water Authority routinely collects and analyzes samples from Lake Mead in order to make biological and chemical assessments of water quality. However, this is the first limnological study since the survey conducted by Prentki, Paulson & Baker (1981) to analyze the chemical, biological, and physical parameters of benthic sediment samples collected from Las Vegas Bay. The goal of this limnological study was to determine the environmental factors that may be related to the density of settled quagga mussels inhabiting Las Vegas Bay of Lake Mead. This study reports that adult and juvenile quagga mussels have inhabited LVB since the third quarter of 2009. No significant differences in pH or electrical conductivity in the benthic sediments were found in Las Vegas Bay; therefore, these parameters could not be statistically compared to the density of settled quagga mussels. Similarly, the composition of benthic sediment (i.e., % clay, % sand, and % silt) was found to be statistically similar, so a comparison to quagga mussel density could not be made. This study found a positive correlation between water depth and the distance of the station from Las Vegas Wash, and quagga mussel density.

Keywords

Animal population density; Benthic sediment; Environmental parameters; Introduced aquatic organisms; Lake sediments; Nevada – Las Vegas Bay; Quagga mussel; United States – Lake Mead; Water quality

Disciplines

Aquaculture and Fisheries | Desert Ecology | Environmental Monitoring

Language

English


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