Date of Award

7-2003

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Ocean Engineering and Marine Sciences

First Advisor

Elizabeth A. Irlandi

Second Advisor

Lee E. Harris

Third Advisor

Junda Lin

Fourth Advisor

George Maul

Abstract

It is important to study the epibiota present on artificial reefs because the establishment of an epibenthic community on artificial reefs that is similar in diversity to the community living on nearby natural rock reefs provides a measure of the suitability of the reefs as an artificial habitat. The goals of this research were to determine the abundance and species composition of the benthic organisms on artificial and natural reefs, assess any difference in organism coverage between reef types, and through this information evaluate whether these artificial reefs are a suitable and successful reef habitat. In the summer of 1999, the Indian River County Commission and the Sebastian Inlet Sportfishing Association deposited three artificial reefs between 11 and 15 nautical miles offshore of Sebastian Inlet, Florida at depths ranging from 21 to 23 m. The epibenthic communities of two nearby natural rock reefs, at depths of 17 and 24 m and distances offshore of 9.5 and 15.5 nautical miles, were compared with those on the artificial reefs. Photo quadrats of the epibenthic community on all the reefs were obtained in the summer of 2002 by SCUBA. Epibiota were identified to genera when possible, organism diversity was calculated using the Shannon Weaver Diversity Index and Evenness was evaluated using Pielou’s formula. Differences in percent coverage of epibiota were analyzed through a non-parametric ANOVA technique using ranked data. In addition, relationships between environmental variables, e.g. - depth, distance from shore, height, length and width of the reefs - and community composition among the reefs were analyzed through Canonical Correspondence Analysis, a direct gradient multivariate analysis technique. A total of 41 taxa in eight different phyla were identified, with algae of the genera Gracilaria and two Ascidians being the most numerous organisms present on the natural reefs, and Balanus (barnacle), two Ascidians and the alga Gelidiopsis spp. being most numerous on the artificial reefs. On the natural reefs, Gracilaria spp. covered the greatest area and on the artificial reefs Ascidians covered the greatest area. Shannon Weaver Diversity Indices showed nearly equal diversity among all five reefs, but statistical analysis showed significant differences in percent coverage between reef types. Multivariate analysis results determined the environmental factors which had the greatest impact on species occurrence were reef height, width, and length. The artificial reefs have developed a near equally diverse epibenthic community as the natural reefs suggesting the concrete railroad ties provide a successful substrate for artificial reefs.

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