6 Avian use and egg selenium at constructed wetland habitat, Salton Sea, California

Wednesday, August 5, 2009: 9:50 AM
Grand Pavillion IV, Hyatt
Thomas W. Anderson , U.S. Geological Survey, Salton Sea Science Office, La Quinta, CA
A. Keith Miles , U.S. Geological Survey, Western Ecological Research Center, Davis, CA
Mark A. Ricca , U.S. Geological Survey, Western Ecological Research Center, Davis, CA
Douglas A. Barnum , U.S. Geological Survey, Salton Sea Science Office, La Quinta, CA
Douglas H. Deutschman , Biology, San Diego State University, San Diego, CA
Rebecca Lewison , Biology Department, San Diego State University, San Diego, CA
Background/Question/Methods

Inflows to the Salton Sea are expected to decrease by at least 30% beginning in 2018 which will affect the availability and quality of critical waterbird habitat along the Pacific Flyway.  The State of California’s Salton Sea Ecosystem Restoration Program has developed a preferred alternative plan intended to mitigate expected impacts by replacing wildlife habitat, controlling fugitive dust problems, and improving water quality.  A major component of this plan is the Saline Habitat Complex proposed as a series of wetland impoundments maintained with a blend of saline Salton Sea water and agricultural drainwater.  The use of drainwater presents the potential for excessive selenium exposure, and the efficacy of creating such habitat needs to be assessed.  A Saline Habitat Project (SHP) pilot study near the southeast corner of the Salton Sea was initiated by the U.S. Geological Survey and the U.S. Bureau of Reclamation.  Bird use and selenium risks associated with this habitat were evaluated across four 10 hectare ponds connected in series by gravity flow. 

Results/Conclusions

Densities of eight waterbird guilds measured Oct 2006 – Sept 2007 indicated use of the SHP was comparable to reference sites at both the Salton Sea and salt ponds in San Diego Bay.  Use by marshbird and pelican/cormorant guilds was limited.  Bird densities and diversity decreased in higher salinity ponds that at times exceeded 300 mgL-1. Predation and flooding were the main causes of nest failure of Black-necked Stilts (Himantopus mexicanus) and American Avocets (Recurvirostra americana) during the 2006 and 2007 breeding seasons.  However, these fates were uncommon for nests located on island habitat within the SHP.  Selenium concentrations in stilt eggs collected from the SHP site and three nearby reference sites likely reflected the use, or lack of use, of agricultural drainwater at each site.  Egg selenium concentrations from the SHP were similar to those in stilt eggs from pooled reference sites. Across SHP ponds, egg selenium concentrations were greatest in the first pond of the series.  Continued monitoring is necessary to develop an accurate ecological assessment of selenium risks at proposed impounded wetlands at Salton Sea and to help guide the Salton Sea Ecosystem Restoration Program.