Summary

Description

In 2005, a twoyear USFWS study 12611N74 was initiated to characterize contaminant exposure by seabirds that nest in colonies at the South Bay Salt Works, within the boundaries of the South San Diego Bay Unit of the San Diego Bay National Wildlife Refuge NWR, CA. This study was conducted in response to observations by seabird colony monitors that black skimmers, in particular have an apparent high incidence of cracked and dented eggs, and posthatch chick mortality. Egg cracking and denting and chick mortality during and after hatching may be contaminantrelated. Concerns were raised, that all of the seabird species nesting at the Salt Works may be experiencing some level of reproductive impairment related to contaminant exposure. This study entailed the collection and analysis of failed eggs of black skimmer, Caspian terns, elegant terns and federally endangered California least terns, and of forage fish that are potentially consumed by seabirds while nesting at the Salt Works. Fifteen skimmer eggs, five Caspian tern eggs, five elegant tern and ten least tern eggs, and 20 composite forage fish samples were collected at the Salt Works during the 2005 nesting season. All of the seabird eggs were evaluated for standard metrics and eggshell thickness. Five composite samples of least tern eggs 2 per sample and individual eggs of black skimmer N15, Caspian tern N5 and elegant tern eggs N5 were submitted to laboratories under contract with the Services Analytical Control Facility catalog 1040073 for chemical analysis. Composite whole body samples of forage fish were submitted for chemical analyses as well. Samples of forage fish included 5 composites of California killifish, 3 composites of topsmelt, and 12 composites of longjaw mudsucker gobiideae. Eggs and fish were analyzed for lipid content, metals, organochlorine pesticides, organotins, polychlorinated biphenyl PCB congeners, and polybrominated diphenyl ethers PBDEs.