Effects of organohalogen contaminants on the metabolic systems and thyroid functions of glaucous gulls (Larus hyperboreus) from Bjørnøya
The main objectives of the current proposal are to investigate the effects of a suite of organohalogen contaminants on the metabolic systems of glaucous gulls, and to examine the implication of circulating thyroid hormone levels in the model. For this purpose, a total of 20 adult glaucous gulls will be captured on their nests during the incubation period at Bjørnøya. Various metabolic system measurements will be carried out, i.e. basal metabolic rate (BMR) and field metabolic rate (FMR), and each bird will be sampled for blood, and finally released in the colony. The present project is part of a three-year (2004-2006) doctoral fellowship (NFR; project no. 160919/V10-Jonathan Verreault) assessing the effects of organohalogen contaminants and metabolites of organohalogens on the endocrine, enzymatic, and metabolic systems of glaucous gulls from Bjørnøya.
Briefly, the adult glaucous gulls will be captured during the incubation period, i.e. from May 20th to June 20th 2004. The trap consists of a snare placed on the edge of the nest bowl and attached to a mechanism triggered by a radio transmitter. Measurements of FMR will be performed by the use of doubly labelled water (DLW), according to published methods by Nagy (1980). Immediately following capture, the birds will be injected 3 mL of DLW (H218O) into the pectoral muscle. A blood sample (1 mL) will be taken from each individual 1 hour after injection of DLW, and released in the colony. The birds will be re-captured within 2 days of DLW injection and a second blood sample will be taken. This second blood sample (12 mL for 1500g of body weight), collected from the brachial vein of the wing, will also be used for measurements of organohalogen contaminant and thyroid hormone levels. The field procedures for measurement of FMR are described by Gabrielsen et al. (1991) and Ellis and Gabrielsen (2001). Measurements of BMR will be performed by the use of indirect calorimetry on the same glaucous gulls captured for FMR measur