Effects of organochlorine residues on eggshell thickness, reproduction, and population status of brown pelicans (Pelecanus occidentalis) in South Carolina and Florida, 1969--76
Blus, L.J.; Lamont, T.G.; Neely, B.S.
Pesticides Monitoring Journal 12(4): 172-184
ISSN/ISBN: 0031-6156 PMID: 461113 Accession: 020939394
Shells of brown pelican (P. occidentalis) eggs collected in South Carolina USA from 1969-1975 and in Florida USA during 1969, 1970 and 1974 were significantly thinner (P > 0.05) than eggshells collected before 1947. Thickness of South Carolina eggshells increased in 1975, and mean thickness of eggshells collected in Florida during 1974 was greater than that of eggshells collected during 1969 and 1970, primarily in Gulf Coast colonies. Residues of 13 organochlorines were found in eggs and tissues of pelicans found dead during 1974 and 1975, although residues in brains of these specimens were not high enough to cause death. Residues of organochlorines, except polychlorinated biphenyl PCB , declined through 1975. PCB increased in eggs from Atlantic Coast colonies. Reproductive success and population status of brown pelicans in South Carolina improved markedly since studies began in 1969. Good reproductive success was reported in 3 of 5 yr from 1973-1977.