Restoration of Propeller Scars in Seagrass Meadows Using Sediment Tubes and Design of a Working Prototype Unmanned Surface Vehicle for Seagrass Studies

Karen Leigh Dreger

A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science Department of Environmental Science, Policy and Geography College of Arts and Sciences University of South Florida St. Petersburg

Abstract

Sediment tubes were placed in the unvegetated trenches created in seagrass meadows by boat propellers. The sediment tubes facilitated the natural recovery by stabilizing the sediments and by allowing recruitment of healthy seagrass from the surrounding, undisturbed area. Still images taken of the study sites before and after restoration were assigned a Braun-Blanquet ranking based on the percentage coverage of seagrass. Statistical analysis, using the Mann-Whitney U Test, supported the visual observation that the sediment tubes successfully facilitated natural restoration of the propeller scars. After two years there was an increase in the percent coverage of seagrass at each of the restored study sites as compared to the sites that were studied but not restored. As part of this project, an Unmanned Surface Vehicle (USV) was modified for studying seagrass. Specifications for a working design are given in the paper.