Dissertation/Thesis Abstract

Invasive and native species interactions: Growth of a native snail is nearly halted by high levels of biomass produced by the invasive New Zealand mudsnail
by Thon, Heather N., M.S., University of Wyoming, 2011, 39; 1501966
Abstract (Summary)

Invasive species can alter the structure and function of ecosystems, reduce biological diversity, and directly change communities through predation, facilitation and competition. The invasive New Zealand mud snail ( Potamopyrgus antipodarum) has varying effects on native species in ecosystems where it has been introduced. We used two different experimental designs to study the interactions between P. antipodarum and the native snail, Fossaria (Bakerilymnaea) bulimoides group in Polecat Creek, Wyoming. We predicted that P. antipodarum would compete with Fossaria because they co-occur and consume similar resources. In the first experiment, we investigated growth at low ambient levels of biomass of each species. We found that growth of Fossaria and P. antipodarum was reduced by the presence of all competitors and that Fossaria grew more in intraspecific than interspecific interactions. This result was probably caused by much higher ambient biomass of the invasive P. antipodarum in the interspecific interaction treatment. Therefore, in our second experiment, we investigated how the snails interacted at an equal, higher biomass. Although growth of Fossaria was nearly halted at this high biomass of competitors, P. antipodarum grew fourteen times faster than the native despite removing less algae. In the high biomass treatment, growth of P. antipodarum was facilitated by the presence of Fossaria. Overall, although growth of both snail species was reduced by the biomass of competitors, for Fossaria, growth was reduced at a rate that was four times higher than P. antipodarum. We concluded that any negative effects on Fossaria do not appear to be caused by traits of P. antipodarum, per se, but rather by a high biomass of snails that occurs when they are highly abundant.

Indexing (document details)
Advisor: Krist, Amy C., Hall, Robert O., Jr.
Commitee: Hall, Robert O., Legg, David
School: University of Wyoming
Department: Zoology & Physiology
School Location: United States -- Wyoming
Source: MAI 50/03M, Masters Abstracts International
Subjects: Ecology, Zoology
Keywords: Competition, Growth, Invasive, Potamopyrgus antipodarum, Wyoming, Yellowstone
Publication Number: 1501966
ISBN: 978-1-267-00120-7
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