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Invasive Mussel Species Impacts the Food Web in Lake Mead

October 1, 2020

In an article for the journal Science of the Total Environment, USGS scientists and others discuss the impact of invasive quagga mussels on the ecosystem of Lake Mead located on the border of Arizona and Nevada. 

Quagga mussels attached to branch retrieved from Lake Mead.
Quagga mussels attached to branch retrieved from Lake Mead.

Invasive dreissenid mussels are causing significant ecological and economic impacts across North America. These mussels were first identified in the Great Lakes during the 1980s where accidental introduction occurred by the release of larvae contained in ship ballast water. Since then, the spread of these muscles has increased, affecting infrastructure, recreational water use, and severely altering aquatic ecosystems.

The USGS has been conducting dreissenid mussel research and control efforts for years. One negative impact of dreissenid mussels is the redistribution of synthetic organic compounds (SOCs) in the ecosystem. SOCs are a class of man-made contaminants which the mussels readily absorb.

USGS researcher holds bucket of quagga mussels taken from Lake Mead
USGS researcher holds a bucket with quagga mussels taken from Lake Mead.

In the reasearch for this article, USGS scientists assessed the distribution of SOCs in the food web of Lake Mead as a result of the introduction of invasive quagga mussels (a variety of dreissenid mussels). Results from this study strongly suggest that the presence of quagga mussels has greatly altered the dynamics of SOCs and other processes in the food web of Lake Mead.  

Specifically, the assessment indicates that a considerable portion of the SOC mass in the lake has shifted from the pelagic (open water) to the benthic (lake bottom) environments due to quagga mussel growth. Other observations are that benthic (bottom-dwelling) species, such as the endangered Razorback Sucker, may be experiencing increased risk of SOC exposure. In addition, stable isotope analysis (carbon and nitrogen) indicated a decrease in the nutritional value of zooplankton to consumers (e.g., Razorback Sucker larvae) since quagga mussels became established, impacting Razorback health and survival.

For more information about this research or to request a copy of the article, please contact Dr. Michael Rosen at the California Water Science Center.

To learn more about USGS food web research on Lake Mead, see: How are Endocrine-Disrupting Compounds Moving Through the Food Web in Lake Mead National Recreation Area?