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Title:Nutritional condition and stress response of fishes along a gradient of habitat quality in the St. Lawrence River: physiological consequences of anthropogenic habitat degradation
Author(s):King, Gregory
Advisor(s):Suski, Cory D.
Department / Program:Natural Res & Env Sci
Discipline:Natural Res & Env Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):conservation physiology
Abstract:Anthropogenic alterations to terrestrial habitat (e.g., urbanization, deforestation, agriculture) can have a variety of negative effects on riverine systems that flow through disturbed landscapes. These in-stream changes can alter aquatic population size and community structure; however, the underlying causal mechanisms remain poorly understood. Although patterns in population size presumably reflect underlying variation in organismal health and condition, such individual-level metrics are rarely evaluated in the context of ecosystem disturbance. Using physiological sampling, we can examine the effects of land use on the health of resident fishes, and improve our understanding of the mechanisms causing population declines. Therefore, the goal of my thesis is to define the relationship between human land use, habitat quality, and the physiological condition of stream fish. To accomplish this goal, I performed two distinct studies that examine these relationships in different ways. Chapter 1 quantified blood parameters relating to nutrition, oxidative stress, and the glucocorticoid (GC) stress response across streams differing in land-use practices at the watershed scale. Results from this study demonstrate natural lands (i.e., forests and wetlands) have stronger influences physiological condition than human land uses (e.g., agricultural and urban areas). Streams with the highest proportions of natural lands resulted in greater free energy, resistance to oxidative stress, and glucocorticoid function. In my second chapter, I used tissue cortisol extraction to examine the relationship between stream quality and the glucocorticoid function of a stream fish community. Results revealed that largemouth bass Micropterus salmoides, brown bullhead Ameiurus nebulosus, and logperch Percina caprodes had altered GC function as a result of anthropogenic stream degradation, whereas white sucker Catostomus commersonii and pumpkinseed Lepomis gibbosus did not. Together, my results show that different species residing in identical habitats can demonstrate a variety of responses to environmental stress, highlighting the variation in physiological ability to cope under poor environmental conditions, as well as the difficulty of predicting the GC dynamics in wild animals. These studies have the potential to provide managers, conservationists, and restoration practitioners with mechanistic information on the effects of land use practices on stream fishes, improving our ability to predict and mitigate the consequences of anthropogenic habitat degradation.
Issue Date:2014-09-16
Rights Information:Copyright 2014 Gregory King
Date Available in IDEALS:2014-09-16
Date Deposited:2014-08

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