Environmental Monitoring and Assessment

, Volume 16, Issue 2, pp 189–200

Contaminant exposure of willets feeding in agricultural drainages of the Lower Rio Grande Valley of South Texas

  • Thomas W. Custer
  • Christine A. Mitchell

DOI: 10.1007/BF00418104

Cite this article as:
Custer, T.W. & Mitchell, C.A. Environ Monit Assess (1991) 16: 189. doi:10.1007/BF00418104


Willets (Catoptrophorus semipalmatus) were collected in June and August 1986 at the outlets of two agricultural drainages into the Lower Laguna Madre of South Texas and at two other Texas coastal sites. Mean liver concentration of arsenic was higher in August than June. Over 20% of the livers had arsenic concentrations elevated above a suggested background level of 5.0 ppm dry weight (DW), but concentrations (maximum 15 ppm) were below those associated with acute toxicity. Selenium concentration in livers varied from 2.3 to 8.3 ppm DW for all locations and represented background levels. Mercury concentrations in livers for all locations (means = 2.0 to 3.4, maximum 17 ppm DW) were below those associated with avian mortality and similar to levels found in other estuarine/marine birds. DDE in carcasses was higher in adults (mean = 1.0 ppm wet weight) than juveniles (0.2 ppm), and higher in August (1.0 ppm) than June (0.5 ppm); however, DDE concentrations were generally at background levels. Based on brain cholinesterase activity, willets were not recently exposed to organophosphate pesticides.

Copyright information

© Kluwer Academic Publishers 1991

Authors and Affiliations

  • Thomas W. Custer
    • 1
  • Christine A. Mitchell
    • 1
  1. 1.Patuxent Wildlife Research CenterU.S. Fish and Wildlife ServiceLaurelUSA
  2. 2.Gulf Coast Research StationVictoriaUSA
  3. 3.Louisiana Cooperative Fish and Wildlife Research Unit, c/o School of Forestry, Wildlife and FisheriesLouisiana State UniversityBaton RougeUSA

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