Date of Award

2013

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

Abstract

Invasive species can be detrimental to freshwater ecosystems. By completing laboratory and field studies to observe processes and behaviors of the invasive Asian Clam (Corbicula fluminea), I documented pathways whereby this invasive species impacts aquatic ecosystems under conditions typical of urbanized streams I found. The predominant pathways by which clams impacted nitrogen (N) cycling was through excretion thus increasing ammonium (NH4+) flux out of sediment and through bioturbation, which increased nitrate (NO3-) diffusion to the sediment and dinitrogen gas (N2) production (i.e., denitrification). The effect was greater under urban conditions, where C. fluminea population density and water column NO3- were higher than in the rural stream. Environmental conditions also negatively impacted the clams' physiology and mortality. The decline in clam condition and high mortality rates, particularly under high nutrient conditions, suggest that it may not be the tolerance of the individuals that allows for the persistence of successful populations, but the life history strategies of the species. Conducting laboratory and field studies on clams' ecosystem effects inspired questions about what factors control clams burial behavior. In laboratory experiments on clam behavior, I found that larger substrates impeded burrowing ability, but that despite ease of movement, clams did not preferentially choose one substrate over another or more laterally once buried. I also found that presence of predators did not affect burial speed or number of clams that buried unless the predator was frequently manipulating the clams. Learning how invasive species behave and how they affect the ecosystem is crucial to management and prevention, and I hope that my research will be of help in those efforts.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

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