SALT TOXICOSIS IN RUDDY DUCKS THAT WINTER ON AN AGRICULTURAL EVAPORATION BASIN IN CALIFORNIA

Agricultural evaporation basins are used as a means to dispose of highly saline underground-tile-drainage water in the San Joaquin Valley (California, USA). The hypersaline water conditions encourage high aquatic invertebrate production, primarily brine shrimp (Artemia franciscana), which attract birds to these sites. Cool winter temperatures ( 70,000 μmhos/cm) resulted in feather salt encrustation and salt toxicosis in ruddy ducks (Oxyura jamaicensis). During December 1998 and January 1999, approximately 200 dead and sick ruddy ducks were collected from an evaporation basin and five healthy control ruddy ducks were collected from a freshwater wetland. Brains contained ≥1,890 ppm sodium (wet tissue mass) in seven dead birds and contained ≤1,150 ppm sodium in the control birds. Liver arsenic, lead, and mercury concentrations were 0.05) between the tw...