Date of Award

5-2024

Document Type

Thesis

Degree Name

Master of Science (MS)

College/School

College of Science and Mathematics

Department/Program

Biology

Thesis Sponsor/Dissertation Chair/Project Chair

Colette Feehan

Committee Member

Lisa Hazard

Committee Member

Matthew Schuler

Committee Member

William C. Sharp

Abstract

The long-spined sea urchin (Diadema antillarum) is a keystone herbivore in the Caribbean and western Atlantic Ocean. It is found in various marine habitats including coral reefs and seagrass beds. On coral reefs, D. antillarum is part of a grazer assemblage that consumes fast-growing macroalgae and reduces competition with reef-building corals. In 1983–84 and again in 2022, D. antillarum experienced mass mortality, and presently populations have not recovered to their pre-1983 levels. Slow population growth is likely due to limited recruitment success under high post-settlement morality caused by a lack of suitable habitat. Here, patterns in larval settlement were examined in the Florida Keys, USA to identify locations with the highest settlement rates, where habitat restoration could be most effective in facilitating population recovery. Replicate settlement plates (4–8 per site) were deployed monthly at two depths (0 and 2 m above bottom) across nine reef sites in a stratified random sampling design as part of two field campaigns (FC1 and FC2) designed to: FC1) test for a difference in settlement rates between inshore patch reefs and offshore bank-barrier reefs (June 2017 to September 2021) and FC2) test for a difference in settlement rates between reefs in the lower Keys and middle/upper Keys (October 2022 to July 2023). Zero-inflated Poisson regressions indicated significantly higher settlement offshore versus inshore and in the middle/upper versus lower Keys but detected no seasonal patterns in settlement. This spatiotemporal study provides guidance to managers in selecting suitable sites for D. antillarum-targeted habitat restoration.

File Format

PDF

Available for download on Saturday, November 08, 2025

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