Contaminants in Eggs of Western Snowy Plovers and California Least Terns: Is There a Link to Population Decline?

Seabirds as regional biomonitors of legacy toxicants on an urbanized coastline

“…Identification of a temporal trend is also complicated because of temporal variability among studies, particularly in mercury concentrations. For example, mean mercury concentrations in our study are lower than those reported at the D-Street Fill CLTE colony in the 1980's (Hotham and Zador, 1995) but higher than mean concentration values reported from CLTE nesting at Tijuana River Estuary from 1994 to 1996 by~300 ng/g dw (Hotham and Powell, 2000). The mechanism causing this variation merits further investigation (see Section 4.1, Elliott and Elliott, 2016).…”

“…Our findings confirm that there is a continued decline in many POPs in the SCB (Maruya et al, 2015), yet many legacy toxicants persist in the SCB. On average, POPs were detected in lower concentrations in this study than those found in the recent past in seabird eggs in the SCB, including DDTs in WEGU nesting at NAS North Island (Jimenez-Castro et al, 1995), PCBs, PBDEs, and DDTs in nesting CATE at Salt Works (Zeeman et al, 2008), PBDEs in nesting CLTE at Salt Works (Zeeman et al, 2008), and PCBs and DDTs in nesting CLTE at the Tijuana River Estuary (Hotham and Powell, 2000). However, mean DDT concentrations in CLTE (764 ng/g ww) nesting at Salt Works were higher by about 400 ng/g ww on average, and above the maximum value of DDT concentrations in 2008 (Zeeman et al, 2008).…”

“…As high trophic level consumers, seabirds in the SCB are exposed to high concentrations of toxicants and declines in seabird populations in the SCB have been linked to exposure to several compounds, (Risebrough et al, 1967;Ohlendorf et al, 1985;Fry, 1994). Numerous other toxicants, including mercury (Hotham and Powell, 2000;Komoroske et al, 2012), selenium (Ohlendorf et al, 1985;Hotham and Powell, 2000), arsenic (Komoroske et al, 2011), PCBs (polychlorinated biphenyls, e.g. industrial and electrical byproducts, Fry, 1995, Schiff and Allen, 2000, Brown et al, 2006, Jarvis et al, 2007, PBDEs (polybrominated diphenyl ethers, e.g., flame retardants, Brown et al, 2006) and CHLs (chlordanes, Ohlendorf et al, 1985, Schiff andAllen, 2000), have also been detected in wildlife, sediments, and waters (Zeng et al, 2005;Dodder et al, 2012) in the SCB.…”

DDT, Chlordane, Toxaphene and PCB Residues in Newport Bay and Watershed: Assessment of Hazard to Wildlife and Human Health

“…Geometric mean concentrations of DDE in eggs from the three sites ranged from 0.23 to 0.56 ppm. Hothem and Powell ( 2000 ) concluded as follows: "Similar or higher mean concentrations in least terns (0.19-1.22 μg/g) from South Carolina (Blus and Prouty 1979 ) and in Forster's terns from Texas (1.6 μg/g) (King et al 1991 ) were not thought to pose a threat to reproduction. Likewise, DDE should not pose a threat to either species in our study.…”

“…Factors such as putrefaction and desiccation in nonviable eggs do not cause loss of DDT, but can produce changes in fresh weight, and therefore the concentration of DDT. Hothem and Powell ( 2000 ) sampled 14 least tern eggs from three locations in the San Diego area. The eggs were taken after the breeding season.…”