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Date of Graduation
Master of Science (MS)
Department of Biology
Christine L. May
Brook trout populations have been extirpated in many Virginia streams due to poor water quality thus establishing populations of brook trout for recreational fishing is an important priority of fisheries management. The ability of a stream to protect developing brook trout (Salvelinus fontinalis) eggs and larval fish from adverse effects from acidification and metal toxicity as well as provide needed minerals such as magnesium (Mg2+) and calcium (Ca2+) for early-stage development is controlled primarily by geology, which influences water hardness and acid-neutralizing capacity (ANC). The focus of this research was on the effects of Ca2+ and Mg2+ water hardness and ANC on the early stages of developing brook trout as well as parameters such as dissolved nitrogen gas (N2), sulfate concentration (SO42-), and ultra-violet light (UV). In order to more effectively accomplish the objectives, the research was performed in a two-phased study; one phase in the lab and the second phase in-situ. A 107-day laboratory experiment was performed where brook trout eggs and larval brook trout were reared in various levels of Ca2+ and Mg2+ water hardness, ANC and SO42- to determine any differences in survival, growth rate, and yolk-sac to whole-body area ratio. A 31-day in-situ study was performed where brook trout eggs were hatched in South River springs, Montebello Fish Culture Station (MFCS) spring and South River main-stem water to determine how survival is impacted by water quality. Results indicated that when water is high in both Ca2+ and ANC, there was a high survival and growth rate. It was also found that brook trout with a ‘home field’ advantage, where brook trout hatched in water where the brood stock were reared and spawned for many generations, had high growth rates and the highest survival. This result implies that genetic adaptation to water quality can facilitate improved early-stage survival and growth. Low levels of Ca2+ correlate with lower yolk-sac to whole-body ratio, which suggests the importance of available Ca2+ during early development. There were conflicting results regarding SO42- as it was detrimental in the 107-day lab study and beneficial in the 31-day in-situ study. There was increased fitness (higher survival and higher individual growth rate) when SO42- was coupled with Mg2+ as opposed to Ca2+ yet the yolk-sac was more depleted when SO42- was coupled with Mg2+ possibly due to the primary uptake method being via diet and not from the environment as it is for Ca2+. For the 31-day in-situ study, a linear regression showed a negative relationship between N2 and percent survival (R2=0.58, p2, UV, ANC, and SO42- (adjusted R2=0.672, p2 but is lacking intermediate values. Due to this gap in data a quadratic regression of only MFCS data was performed which shows that as N2 increases above 100%, survival increases and then begins to decrease rapidly above 103.5% (adjusted R2=0.43, p2 does not have as much of an effect until it reaches higher saturation levels. Springs along the South River have ideal temperature, moderate concentrations of Ca2+ and ANC and do not have excess fine sedimentation however; N2 has a considerable impact on brook trout survival during the early stages of development. This research helps identify some concerns regarding spawning habitat for the establishment of a brook trout population in the South River and it demonstrates the importance of aquaculture in fisheries management as well as furthering the understanding of early-stage development.
Teears, Thomas D., "The effect of water quality on the survival and fitness of brook trout (Salvelinus fontinalis) eggs, alevins and fry in aquaculture and deep springs along the South River in Waynesboro, VA" (2016). Masters Theses. 462.