Effects of an introduced primary producer on trophic interactions in estuaries of the southeastern USA

Invasive species are one of the leading drivers of global ecological change. In particular, the introduction of primary producers can have profound effects on recipient communities, as these species, once established, can spread quickly, can affect multiple energy and nutrient pathways, and can acts as ecosystem engineers that modify or generate habitats. The recent invasion of the red macroalga, Gracilaria vermiculophylla, provides an opportunity to investigate the effects of a prominent non-native primary producer on the estuaries of the southeastern U.S.A. In this region, mudflat habitats were previously devoid of macroalgal primary production. However, since its introduction, G. vermiculophylla has transformed the estuarine ecosystems into a patchwork of macroalgal beds. G. vermiculophylla presents a novel basal resource as well as habitat type, and its effects on the local trophic structure and native species behaviors are unknown. Thus, this dissertation investigates the direct and indirect impacts of the non-native G. vermiculophylla on the trophic interactions of native consumers in estuaries of South Carolina and Georgia. This research aims to: 1) Determine how Gracilaria vermiculophylla directly alters trophic interactions of the southeastern mudflats; 2) Determine the indirect effects of G. vermiculophyllas novel structure on the foraging behaviors of native species. As ecosystems continue to change in response to anthropogenic activities, insights into how introduced species alter community dynamics and native species behavioral responses are essential to predict the outcomes of future species introductions.