PhD Dissertation Defense: Danielle Keller

The PhD Dissertation Defense of Danielle Keller will be presented by UNC-CH’s Curriculum in Environment and Ecology and UNC’s Institute of Marine Sciences. The main location of this event will be in room 222 at IMS in Morehead City, NC. The defense will be streamed live to conference room 3204 on the 3rd floor of Murray Hall on UNC-CH campus in Chapel Hill, NC. This event will be held on Friday, February 23rd at 9:00 AM.

Title:  How the structure and spatial components of habitat affect estuarine communities

Abstract: Habitat describes the place where food is found, refuge is sought, or reproduction occurs, and is therefore a fundamental resource for organisms. To help reverse the consequences of global loss of biogenic habitats, ecologists and managers are assessing how the structure and spatial components of habitat within the landscape can restore lost ecosystem functions and services. Building on these concepts, I attempt to identify how the amount, context (inter-habitat connectivity), orientation (amount of edge habitat), and species composition of biogenic habitat(s) influences faunal habitat-use. By manipulating habitat amount (Ch. 1), I determined the strength of habitat limitation for estuarine fauna depends on the species-identity and life-stage and that overall declines in structured habitats in estuaries may reduce secondary production. In Ch. 2, I restored oyster reefs along different salt marsh geomorphologies to test if this lanscape context affects restoration trajectories as well as fauna habitat-use. I found that oyster reef restoration in salt marsh creeks, compared to other salt marsh shorelines, could increase oyster production. Regardless of landscape context, restoring reefs near salt marsh had little impact on local densities of mobile fauna. To determine the response of flora and fauna to habitat edges (Ch. 3), I conducted a meta-analysis of 211 studies and found marine and terrestrial edges increased fauna foraging and mortality, but had no effect on fauna recruitment. However, fauna density increased in marine edges and decreased in terrestrial edges. In Ch. 4, I assessed how species composition of biogenic habitat affects estuarine communities and found no difference in fauna density, fauna community composition, or the movement of fishes between seagrass sites dominated by eelgrass and shoalgrass. Since we did not find increases in fauna density or movement of fishes to shoalgrass after the seasonal loss of eelgrass, we predict shoalgrass may not serve as a spatial-temporal habitat refuge for fauna, but that it still provides better habitat than mudflats. Overall, these results suggest that habitat amount/availability, as well as the relative amount of edge habitat, have large effects on fauna habitat-use and distributions, where as the impact of landscape context and the species composition of biogenic habitat(s) were less clear.