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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Invasive Species and Pollinator Health » Research » Publications at this Location » Publication #358560

Research Project: Enhancing Water Resources Stewardship through Aquatic and Riparian Weed Management

Location: Invasive Species and Pollinator Health

Title: Aquatic plant community restoration following long-term management of invasive Egeria densa with fluridone treatments

item CAUDILL, JEFFREY - California Department Of Parks And Recreation
item JONES, AJAY - Sepro Corporation
item ANDERSON, LARS - Retired ARS Employee
item Madsen, John
item GILBERT, PATRICIA - California Department Of Parks And Recreation
item SHULER, SCOTT - Sepro Corporation
item HEILMAN, MARK - Sepro Corporation

Submitted to: Management of Biological Invasions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/3/2019
Publication Date: 8/12/2019
Citation: Caudill, J., Jones, A., Anderson, L., Madsen, J.D., Gilbert, P., Shuler, S., Heilman, M. 2019. Aquatic plant community restoration following long-term management of invasive Egeria densa with fluridone treatments. Management of Biological Invasions. 10(3):473-485.

Interpretive Summary: This study using plant community monitoring data over an 11 year period demonstrates that the judicious use of the submersed aquatic herbicide fluridone not only reduces the distribution and frequency of the target aquatic plant Egeria densa, but also allowed the distribution of native plant species to increase, the diversity of native plants to increase, and change the dominant species from Egeria densa to the native Potamogeton richardsonii.

Technical Abstract: The Sacramento-San Joaquin Delta is one of the largest estuaries in North America, providing water for more than 700,000 acres of agriculture, recreation and fisheries habitat. The Delta is home to hundreds of native plants and animals, including the endangered delta smelt (Hypeomesus transpacificus). For decades, the exotic invasive plant, Egeria densa has negatively impacted native habitat and navigation of vessels. Native to South America, Egeria densa is a warm-water submerged plant that exhibits invasive traits, such as quick growth, canopy formation and the ability to establish a monoculture. Covering 3,500 acres, Franks Tract is one of the largest body of water within the San Joaquin Delta and has been infested with Egeria densa since the mid 1990’s. Originally used for agriculture, Franks Tract was flooded in 1936 and is a popular spot for fishing and waterfowl hunting. In 2006 Franks Tract began to be managed at operational scale utilizing fluridone. Egeria densa frequency of occurrence was variable throughout the decade but was reduced in the last 5 years of treatment, while species richness doubled during the same time period. In addition to the increases in species richness, Potamogeton richardsonii, a native, has become the most widespread species. The shift of a monoculture of a non-native species to a more diverse native assemblage, following management with fluridone, is likely to improve fisheries, native species habitat, and waterway traffic.