Thesis (M.S.)--Colorado State University, 1981. / Includes bibliographical references (leaves 41-43). Also available in print.

Thesis (M.S.)--Colorado State University, 1981. / Includes bibliographical references (leaves 41-43). Also available electronically on the Internet.

Thesis (M.S.)--Northern Michigan University, 2006. / Bibliography: leaves 61-67.

This research relates Hg levels in the Common Loon (Gavia immer) to a variety of physical factors. Constructed within the framework of a GIS system, this model analyzes the spatial relationships and the influence of physical land cover factors as a function of distance from the individual loon territories. Thiessan polygons were used to generate the territory for each loon. Buffering of the thiessan polygons was done to establish the boundaries of the individual distance classes and to gather information on the percentage of individual land cover classes within each distance class. Information on precipitation was also gathered. Results from the regression analysis (R2 = 57.3% at the 150m distance class) performed on the variables suggest that the proximity of certain land use types such as cropland, shrub land, and wetlands influence the rates at which Hg is available within an individual territory. Within the 150m and 300m buffers, crop land, shrub land, and wetland exhibited the strongest relationship with the Hg levels in the common loon, with cropland exhibiting a negative relationship suggesting that the proximity of cultivated lands plays a role in decreasing the amount of available Hg in a territory. / Master of Science

Approximately 10,000 tones of Hg are deposited annually as a result of anthropogenic activities. This increased Hg burden is known to have adverse neurological and reproductive effects on Common loons. A positive correlation between mercury (Hg) and selenium (Se) has been reported to exist in marine mammals and various species of marine and aquatic piscivorous birds. It has been hypothesized that the Hg/Se interactions may involve in the multiple mechanisms of Hg detoxification. This study focused on the suggested Hg/Se complex that forms in association with specific proteins. Specifically, this project focuses on the nature of these interactions in different tissues from wild Common loons (Gavia immer) that have been collected by the Canadian Wildlife Service. The Hg and Se concentrations in the various tissues were quantified using AAS. MALDI-TOF-MS and protein sequencing characterized the nature of the Hg/Se complex binding protein. Among the tissues, the liver had the highest concentrations of Hg and Se followed by kidney; muscle and brain. A strong association between Hg and Se was found in liver, kidney and eggs whereas there was no association in muscle and brain. In contrast brain and muscle had highest percentage of organic Hg suggesting that only inorganic Hg is associated with Se. Two Hg-Se binding protein complexes were found in liver both in the 15,200-15,300 Da range while one such complex in the same weight range was found in kidneys, when sequenced it was found that these proteins were the alpha A chain of Hemoglobin. The protein complex found in eggs was unique and although it was impossible to fully sequence it, it represents an unknown protein. The role of Se in Hg toxicity in eggs warrants further study.

White blood cell phagocytosis was investigated and used with avian blood, and assessed as a potential biomarker for mercury immunotoxicity in free ranging birds (common loons). Phagocytosis is an essential immunological function and can be measured using flow cytometry. The assay was assessed with in vitro exposure using whole blood and isolated white blood cells (WBC) from domestic chickens, and with in vivo exposure using whole blood from captive doves and wild loons. McHg at 0.1ppm significantly depressed phagocytic capacity of isolated WBCs without affecting their viability, but did not affect phagocytic activity when added to whole blood up to 50ppm. Also, no significant relationship between blood-Hg level and phagocytic capacity of WBCs was observed in ringed turtle doves fed McHg in their diets, nor in wild common loons having a range of blood-Hg concentrations. The phagocytosis assay is a convenient assay for use in field studies of free-living birds, but is not responsive to McHg exposure in birds, and so is not recommended as a biomarker of immunotoxicity in Hg-exposed loons.

No description available.

No description available.