Lauren Ali

Date of Award

2013

Document Type

Thesis

Degree Name

Bachelors

Department

Natural Sciences

First Advisor

Gilchrist, Sandra

Keywords

Seagrass, Thalassia Testudinum, Halodule Wrightii, Prop Scar, Syringodium Filiforme, Sarasota Bay

Area of Concentration

Environmental Science

Abstract

Propeller (Prop) scarring is a widely recognized source of damage to seagrass beds. This study used aerial photographs taken over a three year period from 2010-2012 and field work done in January of 2012 to determine the number and dimensions of scars in Sarasota Bay, where scarring is occurring and whether it is healing at a significant rate. An average width and depth for scars in Sarasota Bay was calculated based on measurements taken in field. This was combined with the length of prop scars as observed in the aerial photographs to calculate the average apparent area and volume of prop scars in the Bay in general, in different segments of the Bay, and in seagrass beds of different species composition. Of the three species of seagrass examined (Halodule wrightii, Thalassia testudinum and Syringodium filiforme), the most scarring occurred in T. testudinum. Of the five bay segments examined, Upper Sarasota Bay, Sarasota County contained the most scars. A Wilcoxon Rank Sum test showed a significant difference in the length of prop scars between years. A paired t test showed a significant difference between data gathered from aerial photos and from ground truthing. Measurements like depth and width were captured more accurately from ground trothing while the photographs produced a better estimation of scar length. Scarring hotspots were identified in each segment of the Bay where further work is recommended.

Rights

This bibliographic record is available under the Creative Commons CC0 public domain dedication. The New College of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.

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