Date of Graduation

Spring 2015


Master of Science in Biology



Committee Chair

John Havel


Nonindigenous invasive species (NIS) have become increasingly common worldwide and are one of the leading causes of biodiversity loss in freshwater. Three widespread NIS in Wisconsin lakes are rusty crayfish (Orconectes rusticus, RC), banded mystery snails (Viviparus georgianus, BMS), and Eurasian water-milfoil (Myriophyllum spicatum, EWM), species that commonly co-occur. All three of these species can be very abundant and two (EWM and RC) are known to be individually damaging. The current study evaluated the impacts and interactions between these three invaders on seven common plant species and three common snails in a three-factor split-plot experiment conducted in 12 outdoor tanks (2.1 m3). Results indicate that RC had significant negative effects on final biomass of all but one plant species, with the greatest total effects on single-stemmed and branched species. Rusty crayfish significantly reduced biomass of native snails, but not the invasive BMS. Overall, main effects of RC on native plants and snails were much greater than effects of either EWM or BMS, or the combined effects of these invaders. These impacts, together with the rapid production and growth of EWM fragments, suggest that RC may facilitate the spread of EWM in lakes by removing competition from native plants.


banded mystery snail, Eurasian water-milfoil, rusty crayfish, invasive species, invasional meltdown, mesocosm

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© Adrienne Rose Gemberling

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