Geology topics

Glen Fox

Publications and source records attributed to Glen Fox.

3 recordsLinked to original sources

USGS1991

Reproductive outcomes in colonial fish-eating birds: A biomarker for developmental toxicants in Great Lakes food chains: I. Historical and ecotoxicological perspectives

Colonial fish-eating birds have been used as convenient model populations in which to study the impact of chronic exposure to complex mixtures of persistent lipophilic environmental contaminants within the Great Lakes ecosystem. To date, published reports of contaminant-induced adverse reproductive outcomes exist for six species. We briefly review the studies of the herring gull ( Larus argentatu s), Forster's tern ( Sterna forsteri ), and the double-crested cormorant ( Phalacrocorax auritus ) to illustrate the use of reproductive outcomes in fish-eating birds as a biomarkerfor developmental toxicants in Great Lakes food chains. We discuss the management implications of using various species for such purposes. We recommend that cormorants be used more extensively in biomonitoring programs to measure exposure and effects of polyhalogenated aromatic hydrocarbons and other contaminants in aquatic food chains in the Great Lakes.

Great Lakes↗

USGS1991

Reproductive outcomes in colonial fish-eating birds: A biomarker for developmental toxicants in Great Lakes food chains: II. Spatial variation in the occurrence and prevalence of bill defects in young double-crested cormorants in the Great Lakes, 1979–1987

Congenital malformations are relatively uncommon in most wild bird populations. Here we document the occurrence of bill malformations in double-crested cormorant ( Phalacrocorax auritus ) chicks from colonies in Green Bay and elsewhere in the Great Lakes and in reference areas off the Great Lakes, in the years 1979 through 1987. In the Great Lakes, 31,168 cormorant chicks were examined during 147 visits to 42 colonies. Seventy of these chicks had crossed or deflected bills or bills in which the mandibles differed in length. Only two of the 20,962 chicks examined during 82 visits to 35 colonies in reference areas located in the prairies and northwestern Ontario had bill defects. The probability of observing a malformed chick on a visit to a colony in Green Bay was 10 to 32 times greater than on a visit to a colony in the reference areas. Bill defects were observed at only two (6%) of the colonies in the reference areas. This proportion was exceeded in six of eight geographic regions within the Great Lakes and was highest (73%) in Green Bay colonies. The prevalence of malformed chicks in Green Bay (52.1 per 10,000)was markedly greater than in all other regions during this period. These bill defects are an example of developmental asymmetry and are an indicator of developmental stability within local populations. Other investigations in Lake Michigan suggest that chemicals such as polyhalogenated aromatic hydrocarbons (e.g., PCBs) that induce aryl hydrocarbon hydroxylase are responsible for the defects observed defects.

Great Lakes↗

USGS1991

Great lakes embryo mortality, edema, and deformities syndrome (glemeds) in colonial fish-eating birds: Similarity to chick-edema disease

Several species of colonial fish-eating birds nesting in the Great Lakes basin Includ-ing herring gulls, common terns and double-crested cormorants, have exhibited chronic impairment of reproduction. In addition to eggshell thinning caused by high levels of DDT and metabolites, the reproductive impairment is characterized by high embryonic and chick mortality , edema, growth retardation, and deformities, hence the name Great Lakes embryo mortality , edema, and deformities syndrome (GLEMEDS). The hypothesis has been advanced that GLEMEDS in colonial fish-eating birds resembles chick-edema disease of poultry and has been caused by exposure to chick- edema active compounds that have a common mode of action through the cytochrome P-448 system. Detailed evidence has been collected from the following three groups of studies on herring gulls in the lower Great Lakes during the early 1970s; Forster’s terns in Green Bay, Wisconsin in 1983; and double-crested cormorants and Caspian terns in various locations in the upper Great Lakes from 1986 onwards. It has proved difficult to establish not only the onset of the disease in the various species at various locations but also the period in which chick-edema active compounds were released. Anecdotal evidence suggested that serious egg mortality . © 1988 by Hemisphere Publishing Corporation.

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