Term of Award

Spring 2014

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (open access)

Department

Department of Biology

Committee Chair

Daniel Gleason

Committee Member 1

Risa Cohen

Committee Member 2

Checo Colon-Gaud

Abstract

Documenting patterns of sessile invertebrate community development is important for predicting recovery patterns after disturbance and designing effective marine reserves. In the South Atlantic Bight, invertebrate assemblages can differ significantly from one rocky outcrop to another, but the factors driving these differences are not well understood. I tracked community development for fourteen months at four rocky outcrops at Gray’s Reef National Marine Sanctuary (GRNMS) to address the predictions that (i) developing sessile invertebrate communities in this system do not exhibit a predictable pattern of succession and (ii) recolonization patterns for small patches of open space that become available are influenced by the composition of the invertebrate community in the immediate vicinity. Community development was followed for 14 months on paving tiles (30 x 30 cm) deployed in July 2012 by photographing these tiles, along with the adjacent natural community, each month through September 2013. Species composition, percent cover, and diversity were determined each month.

Sessile invertebrate taxa colonizing tiles were similar across all four sites in the first three months after deployment, but diverged over time. At all sites, developing communities exhibited lower percent cover and diversity than their adjacent existing communities over the fourteen months of the study, but analyses of similarities (ANOSIM) did provide evidence of convergence over the long term. These results indicate that succession of sessile invertebrates is not a predictable process in this system and that the extant community plays a role in deciding the final outcome of species re-establishment. Thus, differences in invertebrate community structure among rocky outcrops likely persist in this system because the extant community influences recruitment.

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