Interagency Management Action Plan (I-MAP) for Quagga Mussels

Following the discovery of quagga mussels in Lake Mead, a variety of agencies, including National Park Service (NPS) Lake Mead National Recreational Area (LMNRA), Bureau of Reclamation (USBR), Southern Nevada Water Authority (SNWA), Nevada Department of Wildlife (NDOW), U.S. Fish and Wildlife (USFWS), Clean Water Coalition (CWC), and U.S. Geological Survey (USGS) have set up monitoring programs to evaluate and gain information to help minimize the impacts or potential impacts of quagga mussels to their facilities and lake ecology. Current monitoring activities and anticipated environmental impacts are depicted in Figures 1 and 2. While the agencies have worked closely and shared monitoring data and findings from the beginning of the infestation, there has been no documented comprehensive monitoring program to describe and record the various quagga mussel-related monitoring needs relative to interagency objectives for Lakes Mead and Mohave. Ad hoc interagency quagga mussel meetings attended by representatives of the above-listed agencies and others served as a springboard for gathering the information with which to establish this Interagency Monitoring Action Plan (I-MAP), which outlines agency objectives related to quagga mussel monitoring and provides approaches to realize these objectives. At the time of this document’s publication, the “I-MAP quagga mussel coordination team” included representatives from the following agencies: LMNRA, USBR, SNWA, NDOW, CWC, AZGFD, USFWS, MWD, UNLV, DRI, and UNR (Figure 3). I-MAP team members and their respective agencies provide technical, logistical, and financial support in monitoring quagga mussels and their environmental impacts to Lake Mead. The purpose of the I-MAP team is to coordinate monitoring relevant to the I-MAP

Quagga mussels in the western United States: Monitoring and Management

Dreissenid mussels including zebra mussel (Dreissena polymorpha Pallas, 1771), originating from the Ponto-Caspian area, and quagga mussel (Dreissena rostriformis bugensis Andrusov, 1897), originating from the mouths of the Rivers Southern Bug and Dnieper are both species native to Eastern Europe, which were accidently introduced into the Laurentian Great Lakes in North America in the 1980s in ballast water (Carlton 2008; Van der Velde et al 2010). Dreissenid mussels have created severe ecological, recreational and economic impacts on many systems because they are biofoulers and efficient ecological engineers that filter large quantities of water. Examples of these wide-ranging impacts are discussed by Turner et al. (2011) in this issue. Ecologically, invasive dreissenid species have been shown to affect a variety of changes, such as altering phytoplankton species composition and nutrient dynamics in the Great Lakes (Lavrentyev et al. 1995; Vanderploeg et al. 2001; Conroy et al. 2005; Zhang et al. 2011), impacting other organisms by direct colonization or indirect competition for food and/or space, and increasing water clarity by removing suspended particles (e.g., phytoplankton, debris, silt and microzooplankton) in the water column. The increased water clarity can then affect other ecosystem components, such as species abundance and community composition of microalgae and aquatic plant communities. The zebra/quagga mussel has become arguably the most serious nonindigenous biofouling pest introduced into North American freshwater systems (LaBounty and Roefer 2007) and one of the world\u27s most economically and ecologically important pests (Aldridge et al. 2006). The spread of dreissenid mussels in recent years has slowed in recent years in many systems as the most vulnerable bodies of water have been colonized (Johnson et al. 2006), but will presumably continue for many years, until the entire range is filled (Strayer 2009)

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Abundance and size of quagga mussels (Dreissena bugensis) veligers in Lake Mead, Nevada-Arizona

The planktonic veligers of the invasive quagga mussel were present year-round from April 2008 to March 2009 in Lake Mead, with high abundance from September to October (\u3e20 veligers/L), whereas the percentage of competent veligers, in terms of the ability to settle, peaked from November 2008 to January 2009 (\u3e60%). The results from this experiment are useful in understanding the life history and population dynamics of quagga mussels in the lower Colorado River Basin

Settlement and Growth of quagga mussels (Dreissenia rostriformis bugensis Andrusov, 1897) in Lake Mead, Nevada-Arizona, USA

Settlement and growth of quagga mussels Dreissena rostriformis bugensis were monitored in Lake Mead, NV, USA, where the first dreissenid occurrence was confirmed in the western United States. To measure the settlement rate of these invasive mussels, seven acrylonitrile butadiene styrene (ABS) pipes were attached to a line in shallow water (7.7 m below the surface) since November 23, 2007; eight ABS pipes were placed on another line in deep water (13.4 m below the surface) since January 3, 2008. Quagga mussels were sampled from these pipes on March 19, May 21, July 9, October 20, and December 19, 2008. Active settlement of veligers was recorded in all sampling events. The settlement rates of quagga mussels did not differ among the two lines and the highest settlement rate was found from October 20 to December 19. Three methods were used to estimate the growth of quagga mussels in Lake Mead: caged mussels, size distribution analyses on both natural populations and mussels attached to ABS pipes. Caged mussels were held in Las Vegas Boat Harbor from July 31, 2007 to March 19, 2008, where smaller mussels grew faster than larger ones. Size distribution data on two natural populations of quagga mussels collected from Sentinel Island and Indian Canyon in 2007 also showed that the growth rates decreased significantly as mussel size increased. Shell length data of cohorts collected from the ABS pipes were also used to estimate the growth of quagga mussels. The growth patterns of quagga mussels from the two lines were quite similar with the lowest growth rates detected from late summer to early autumn. The information on settlement and growth of quagga mussels from this study can help understand their population dynamics in the western United States

Environmental factors affecting settlement of quagga mussel (Dreissena rostriformis bugensis) veligers in Lake Mead, Nevada-Arizona, USA

Environmental factors that can affect the settlement rate of quagga mussel veligers include flow velocity, water temperature, pH, dissolved oxygen (DO), conductivity, total organic carbon (TOC), and the surface roughness of monitoring substrates. In the present study, six artificial substrates, Acrylonitrile Butadiene Styrene (ABS) plastic, High Density Polyethylene (HDPE) plastic, Concrete Underlayment Board (CUB), aluminum, stainless steel and fiberglass, were used to monitor the settlement of quagga mussel veligers at different water depths in Lake Mead, Nevada-Arizona, USA. Considering the hierarchical data structure of observed mussel densities, we investigated the relationship between mussel settlement on monitoring substrates and the surrounding environmental variables by applying the Linear Mixed Effects (LME) model. After normalization, the above six environmental variables were considered as independent factors in fixed-effect calculation, while water depth and substrate roughness acted as the group variable and the random term, respectively. The results indicated that flow velocity, water temperature, and DO were significant factors in determining the mussel settlement on substrates. TOC was barely significant while conductivity and pH had no impact on settlement of quagga mussel veligers. As to the random effect, no preference for substrate type could be found, while water depth caused considerably more variation in modeling since it might correlate with most environmental variables. There is need to emphasize the critical role of flow velocity which is often ignored by biologists - higher flow velocities significantly decreased the settlement of quagga mussel veligers on substrates. Therefore, to more efficiently monitor quagga mussel colonization in water bodies, artificial substrates should be deployed in areas without strong flow

Interagency monitoring action plan (I-MAP) for quagga mussels in Lake Mead, Nevada-Arizona, USA

Following the discovery of quagga mussels in Lake Mead, Nevada-Arizona, USA, a variety of federal, state and regional agencies set up monitoring programs to evaluate and gain information to help minimize the impacts, or potential impacts, of quagga mussels to their facilities and lake ecology. While the agencies have worked closely and shared monitoring data and findings from the beginning of the infestation, there has been no documented comprehensive monitoring program to describe and record the various quagga mussel-related monitoring needs. Ad hoc interagency quagga mussel meeting representatives established an Interagency Monitoring Action Plan (I-MAP), which outlines agency objectives related to quagga mussel monitoring and provides approaches to realize these objectives. I-MAP team members and their respective agencies provide technical, logistical, and financial support in monitoring quagga mussels and their environmental impacts to Lake Mead. The goal of this effort is to develop a long-term, cost-effective, and consistent monitoring plan for quagga mussels in Lake Mead to inform various agencies and to gain efficiencies from shared operations and information. The plan attempts to build upon current monitoring activities and capabilities, identifies the next steps that can occur within existing capabilities and, finally, outlines gaps and areas of future need