Document: LEN-3-74-11

Community resistance to an invasion attempt by Daphnia lumholtzi.

LENNON, J.T.* ^1,2, V.H.SMITH ² and A.DZIALOWSKI ²

Dartmouth College, Hanover, NH 03755, USA ¹
University of Kansas, Lawrence, KS, USA ²

Abstract:
Although biological invasions are becoming increasingly more common, a majority of introduced exotic species fail to establish viable populations in new environments. Current ecological research suggests that invasion success can be influenced by "biological resistance", which is determined by the native community structure. We examined the effects of biological resistance on the recent invasion of Daphnia lumholtzi, by introducing this exotic species into native zooplankton communities in a series of experimental mesocosms exposed to a strong nutrient gradient. We hypothesized that nutrient enrichment, zooplankton production, and zooplankton species diversity would influence the success of a one-time invasion attempt by D. lumholtzi. Nutrient enrichment lead to significant increases in zooplankton biomass and also resulted in a significant decline in zooplankton species diversity. However, the invasion success of D. lumholtzi was not directly influenced by nutrient enrichment. Instead, the invasion success of D. lumholtzi appeared to be most strongly influenced by the presence and abundance of the littoral zooplankton species, Chydorus sphaericus in the water column. These results suggest that species- or functional-identity may be an aspect of community structure that influences the invasion success of introduced D. lumholtzi.

Keywords: biological invasions, nutrient enrichment, diversity, biotic resistance, zooplankton, _Daphnia lumholtzi_

This abstract is being presented at: 1:15 PM in session:
Oral Session #47: Zooplankton Ecology.