Theses and Dissertations

Copyright Statement

All rights reserved. This publication is intended for use solely by faculty, students, and staff of Nova Southeastern University. No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, now known or later developed, including but not limited to photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the author or the publisher.

Defense Date

4-9-2003

Document Type

Thesis - NSU Access Only

Degree Name

M.S. Marine Biology

Department

Oceanographic Center

First Advisor

Bernhard Riegl

Second Advisor

Richard E. Dodge

Third Advisor

Pamela Reid

Abstract

High latitude reef communities consisting of typical Caribbean fauna of variable composition and density exist on four parallel ridges at varying depths along the Broward County (FL, USA) coast. At least two of these ridges, at 7-13m and 15-30m depth, are drowned early Holocene coral reefs of 5 ky and 7 ky uncorrected radiocarbon age, respectively. Previous work has shown that the present reef communities growing on these ridges can be detected and mapped using acoustic remote sensing and has suggested that different benthic assemblages may exist between each of these reefs. In this study, in situ community data was taken in four corridors on each reef using fifty-meter line-intercept transects. Multidimensional scaling analyses of the in situ community data show distinct differences in benthic community structure across several spatial gradients within the county. This clustering agrees well with an acoustic data set, taken in the same four corridors along the Broward County coast. Analysis of diversity statistics revealed that whereas species diversity (H’) was consistent throughout the county, species richness (d) and eveness (J’) increased along a north-south gradient. Total scleractinian cover was generally low in all areas (<6% mean cover), and also increased along a north-south gradient in the reef communities closest to shore (ridge complex communities). Percent scleractinian coral cover on all other reef communities (inner, middle, and outer reefs) was consistent throughout the county with Montastrea cavernosa being dominant over the M. annularis complex, which is the more typically dominant reef builder in Caribbean systems. Notably absent from the scleractinian fauna of this area was the major Caribbean reef-builder Acropora palmata. A rich alcyonacean fauna (12 genera) was present on all reefs in the county, and typically was the faunal group with highest cover (~20% mean cover countywide) and most important in terms of determining community structure. Although 2-year average water temperature never fell below 21 degrees C, which is within generally accepted limits for reef building, scleractinia were small in size and though not directly investigated, no observable evidence for late Holocene reef building exists. Habitat maps produced from this study show evidence for the unevenly distributed existence of at least six different community types within Broward County: Type 1: shallow, sponge-dominated community; Type 2: shallow, stony- and soft coral-dominated community; Type 3: shallow, zoanthid and soft coral-dominated community; Type 4: soft coral-dominated community; Type 5: zoanthid and macroalgae-dominated community; Type 6: Macroalgae, massive sponge, and soft coral-dominated community.

Comments

This work was made possible by partial funding from the Broward County Dept. of Planning and Enviornmental Protection (DPEP), Coastal Planning & Engineering Inc., and the National Coral Reef Institute (NCRI) through the NOAA Coastal Ocean Program under award number NA16OA1443.

To access this thesis/dissertation you must have a valid nova.edu OR mynsu.nova.edu email address and create an account for NSUWorks.

Free My Thesis

If you are the author of this work and would like to grant permission to make it openly accessible to all, please click the Free My Thesis button.

Share

COinS