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Document Type

Thesis - University Access Only

Award Date

2007

Degree Name

Master of Science (MS)

Department

Wildlife and Fisheries Science

First Advisor

Regg Neiger

Abstract

Population surveys have indicated a decline in the continental scaup population (lesser [Aythya affinis] and greater [A. marila] scaup combined) for the past 20 years, although many other waterfowl species have recovered from similar declines during this same time period. Key areas of concern identified as essential to address this population decline included the affects of contaminants on reproduction, and identification of diseases which may have a negative impact on general health and body condition. The objectives of this study were (1) to measure hepatic concentrations of several important elements in lesser scaup during spring migration, (2) to compare element concentrations by gender and collection location, (3) to compare the data of this study to published data from other studies of lesser scaup, and (4) to perform gross and histological examinations of lesser scaup during spring migration to subjectively assess their general health. Lesser scaup were collected from several sites throughout the upper Midwest during the 2003 and 2004 spring migrations for analysis of hepatic element concentrations. Inductively coupled plasma-atomic emission spectrophotometry (ICP) analysis was used to measure concentrations of 24 elements in the livers of the ducks collected. During spring migration in 2004, gross necropsy examination and histological examination of several tissues were also completed on the lesser scaup collected. In this study, the hepatic concentrations of arsenic, boron, cadmium, calcium, chromium, copper, iron, lead, magnesium, manganese, mercury, molybdenum, nickel, potassium, sodium, thallium, and zinc likely represented normal physiological or background levels. The significance of hepatic concentrations of aluminum, antimony, barium, cobalt, phosphorus, and sulfur remained unclear due to a lack of data concerning concentrations of these elements in waterfowl. Compared to females, liver cadmium was significantly higher in the male lesser scaup collected, and negative impacts of cadmium on male reproduction have been reported. Barium and cobalt were detected in ≥50% of lesser scaup livers in this study, although previous studies have reported a low percentage of ducks with measurable concentrations of these elements. Due to a lack of established data concerning barium and cobalt in ducks, the importance of these findings is undetermined. The geometric mean selenium concentration in the lesser scaup collected (3.33 ppm ww) was above the level considered to adversely affect reproduction in lesser scaup (>3.0 ppm ww), and approximately 49% of the female lesser scaup collected had individual hepatic concentrations >3. 0 ppm ww selenium. The data from this study indicated elevated selenium levels were present in lesser scaup in the upper Midwest, and reproduction may be impaired as a result. Additionally, the lesser scaup collected in this study appeared to have adequate general health, although the recorded body weights of both male and female ducks were consistent with the previously documented trend of declining body masses in lesser scaup. Based on a lack of prominent tissue inflammation and destruction, the acanthocephalan, cestode, nematode and protozoan helminthes observed by histological examination were likely infesting a normal host, the lesser scaup duck; however, trematodes of the family Schistosomatidae incited notable tissue inflammation in some of the scaup examined. This study was the first to document and describe tissue distribution and pathology associated with avian schistosome parasites in lesser scaup ducks collected in the upper Midwest.

Library of Congress Subject Headings

Lesser scaup -- Middle West
Lesser scaup -- Effect of chemicals on -- Middle West
Bird populations -- Middle West

Description

Includes bibliographical references

Format

application/pdf

Number of Pages

128

Publisher

South Dakota State University

Rights

Copyright © 2007 Angela E. Pillatzki. All rights reserved.

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