Effects of Watershed Land Use on The Seasonal Energy Dynamics, Condition, and Parasite Communities of Stream Fish

Abstract

ii DedicationTo my parents for their patience and understanding while raising a child obsessed with the natural world. You never knew what creature you would find hidden somewhere in your house next, yet you never discouraged my curiosity. For that I am forever grateful. To the Wards and their ongoing support and encouragement. I am so fortunate to have joined such an amazing family. And finally, to my partner Taylor, to whom I simply say, thank you, thank you, thank you.iii Abstract While it is generally considered that habitat degradation negatively impacts resident fish, the physiological mechanisms behind this trend are not well understood.Applying scientific techniques to increase our understanding of how habitat influences individual physiology and how that, in turn, influences fish population dynamics is becoming an important approach to environmental monitoring. In Chapter 2, I quantify how watershed land use influences the over winter energy reserves and health of a small stream fish and demonstrate that land use influences these metrics differently for females and males of the model species. In Chapter 3, I investigate the parasite communities of juvenile fish residing in a range of impacted streams to identify potential bioindicators of habitatand consequently fishhealth. These data are the first of their kind for both species examined, and are also the first time these techniques have been used to address these unique research questions.iv

Ecological correlates of baseline and maximum glucocorticoid concentrations in wild freshwater fish

“…Comparable results were found in other studies using generalist species (e.g. creek chub [Blevins et al 2013]; central mudminnow [Chapman 2014]). It has been hypothesized that more robust species, typically the species in greater abundance in a degraded system, may be inadequate bioindicators as they are less affected by the degraded habitat (Chapman 2014).…”

“…If more sensitive species do show a difference in stress response between the two streams it is possible that the more susceptible species are being negatively impacted by the degradation while other, more hardy species are not. This will assist in future management practices as some species may be inappropriate to use as bioindicators of degraded habitats (Chapman 2014). The difference in GC concentrations demonstrated that both baseline and maximum cortisol levels were the highest in the spring.…”

“…creek chub [Blevins et al 2013]; central mudminnow [Chapman 2014]). It has been hypothesized that more robust species, typically the species in greater abundance in a degraded system, may be inadequate bioindicators as they are less affected by the degraded habitat (Chapman 2014). Though little statistical significance was observed, Chapter 2 of this thesis does show trends indicating that polymorphic species may differ in their response to an environmental challenge.…”

“…To do this, studies would need to be done in the area prior to any planned human activity (which is rarely done [Wikelski and Cooke 2006]) to determine what time of year the community as a whole is more sensitive to environmental challenges. Ideally, a variety of species, including those more sensitive as well as more robust species, should be used to determine these baseline measurements (Chapman 2014). In addition to this, follow up studies in the area should be conducted to determine any changes in community structure or species' physiological responses that may have occurred as a result.…”