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(502) Peak metabolic rate: A performance-based indicator of pesticide exposure in birds .
Buttemer, William1, Fildes, Karen1, Astheimer, Lee*,1, 1 Institute for Conservation Biology, University of Wollongong, Wollongong, NSW, AUSTRALIA, Australia
ABSTRACT- One of the difficulties in assessing the extent and duration of physiological compromise following pesticide exposure is identifying appropriate variables to measure. We believe that peak metabolic rate (PMR) is an ideal performance indicator for this purpose as it requires the integrated function of a suite of enzymes, organelles, cells, tissues, organs, and organ systems and thus provides a meaningful measure of an animal's overall physiological performance. We measured peak oxygen consumption in House Sparrows while they were flying in a revolving, flow-through chamber. The PMR measurements of aviary-housed birds are highly repeatable over many weeks of captivity. Before exposure to organophosphates, the mean PMR of these birds was over 12-times greater than their basal metabolic rate. The mean PMR values of birds given high doses (100 mg/kg) of fenitrothion, an organophosphate, were 35, 65, 85%, and 100% of pre-exposure levels at 2, 6,14, and 21 days after ingestion. By contrast, the plasma cholinesterase levels of these birds had returned to normal by 2 days after pesticide ingestion and their plasma hemoglobin content was unchanged throughout this period. Birds given lower doses of fenitrothion (60 mg/kg) also showed significant decreases in PMR 2 days after pesticide intake (70% of pre-pesticide values) and had fully recovered by 14 days after exposure. These results show PMR to be an effective indicator for assessing both the extent and duration of pesticide-induced physiological compromise in birds.
Key words: metabolism, sub-lethal, organophosphate, avian
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