Theses and Dissertations

Defense Date

12-10-2015

Document Type

Thesis

Degree Name

M.S. Marine Biology

First Advisor

Charles G. Messing

Second Advisor

Amy C. Hirons

Third Advisor

Christopher Blanar

Abstract

Artificial reefs (ARs) are generally created with the intention of increasing local fish populations, biodiversity and corresponding habitat productivity, most often in support of commercial and recreational uses (e.g., diving and fishing). Numerous studies have investigated the communities that develop on artificial reefs. By contrast, far less research has focused on the surrounding infaunal communities, which represent critical trophic resources for many species that populate both natural and artificial reefs, and which may be affected both by AR deployment and the organisms that subsequently recruit to them. This study compared infaunal organism abundances at four sites between the inner and middle reefs off Broward County, Florida, before deployment of a series of Florida Department of Transportation (FDOT) AR boulders in 2009 (pre-construction) and four years later in 2013 (post-construction). Samples consisted of sediment collected in hand-held core tubes taken on open sediment adjacent to the proposed ARs and along transects at distances 3 m and 7 m from the ARs post-construction. Sample depths ranged from 12.1 to 14.6 m. Analyses were carried out on organisms retained on a >0.5 mm sieve and identified to the lowest practical taxonomic level. Data consisted of abundances rather than densities, because pre-construction samples did not record sediment volume per core. A total of 163 taxa were identified, of which only 50 were identified to genus and 64 to species. Polychaete families Spionidae, Sabellidae, Syllidae, and Hesionidae, and sipunculan superfamily Phascolosomatidea dominated pre-construction samples. Polychaetes also dominated post-construction samples, with high relative abundances of Sabellidae and Hesionidae, but with increased proportions of bivalves and amphipods. Statistical analyses (PRIMER, PERMANOVA, and SIMPER) determined whether infaunal composition, richness and, diversity differed among samples by year, site and distance from AR boulders. A slight but statistically insignificant difference in species diversity appeared between 3- and 7-m distances between years. However, composition, richness, and diversity of infauna did not differ either between pre-and post-construction samples or by sample distance from the adjacent AR boulders. The increase in homogeneity among samples post-construction may reflect recovery following the disturbance created by AR deployment, or a response to different benthic conditions generated by AR deployment. As other studies have suggested that AR fauna may influence surrounding infaunal communities to distances greater than 7 m, and that conditions may not stabilize around ARs for up to ten years following deployment, additional sampling is recommended to determine the longer-term effects of the FDOT ARs on infauna and benthic habitat (e.g., sediment composition, water movement) and assist in determining best practices for future AR deployments (e.g., composition, structure, location).

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