Predicting community dynamics in the wake of invasion : a case study of the zebra mussel

Author

Jeffrey Robert Duncan

Date of Award

8-1996

Degree Type

Thesis

Degree Name

Master of Science

Major

Zoology

Major Professor

James A. Drake

Committee Members

Dewey Bunting, Gerald Vaughan

Abstract

The fragile complexity associated with aquatic ecosystems has proven, in past situations, to be vulnerable to effects induced by invaders (e.g., the sea lamprey invasion of the Great Lakes). Unlike many other invasions, the zebra mussel (Dreissena polymorpha) threatens to disrupt the natural food webs of North American waters in unprecedented proportion. The full impact of the zebra mussel invasion of North America is yet to be experienced, though it will likely result in wholesale changes in aquatic biodiversity due to the mussel's ability to exploit open niches and out-compete indigenous species. This study provides a synopsis of the invasion and a review of history characteristics of the zebra mussel that contribute to its success as a colonizing species. Finally, a computer simulation model composed of a set of differential equations is proposed to analyze the direct and indirect ecological effects induced by the zebra mussel invasion. The role Dreissena,/em> plays in altering aquatic primary production, light availability, and nutrient dynamics are considered. Predictions of future ecosystem/community structure are proposed and the plausibility of alternative community states are assessed with consideration given to properties associated with community assembly including interspecific competition and intransitive switching. In addition, the application of non-linear analysis suggests evidence of chaos within ecosystem trajectories, indicating dependence upon initial conditions such that future attempts at inter-ecosystem extrapolation of ecological effects will be challenging.