HCNSO Student 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


Document Type

Thesis - NSU Access Only

Degree Name

M.S. Marine Biology


Oceanographic Center

First Advisor

Bernhard Riegl

Second Advisor

Bernardo Vargas-Angel

Third Advisor

Curtis Burney

Fourth Advisor

Patricia Blackwelder


Trends of increasing coastal eutrophication and atmospheric pCO2 require investigation to predict the combined effects on coral and reef condition and growth. Increases in nutrient concentrations have been observed over the past several decades in a number of reef systems, and it has been predicted that this will adversely affect coral growth rates. The species targeted by this research, Acropora cervicornis, is among the most important reef-builders in the Caribbean and has suffered widespread mortality in southern Florida. Approximately 192 branch tips were harvested from two local populations of A. cervicornis and maintained in the laboratory, where the growth rate was measured before, during, and after exposure to elevated levels of nitrate (N) (5 µM and 10 µM), phosphate (P) (2 µM and 4 µM), and/or pCO2 (CO2) (~700-800 µatm). During the control period, there was no significant difference in growth rate between the treatments, with a mean growth rate of 4.84 mg d-1. During Period 2, the first enrichment period, the largest decrease in growth rate was caused by the combined NPCO2 treatment (mean growth rate of 0.51 mg d-1). The least effect on growth rate was caused by the N treatment (mean growth rate of 4.39 mg d-1). During Period 3, the second enrichment period, the lowest growth rate was again found in the NPCO2 treatment tanks (mean growth rate of 0.03 mg d-1). The highest growth rate among the treatments was in the N treatment tanks (mean growth rate of 1.90 mg d-1), however there was no significant difference between the growth rates of the N, P, NP, CO2, NCO2, and PCO2 treated corals during this period. The mean growth rates in the Control tanks were 7.59 and 7.32 mg d-1 during Periods 2 and 3, respectively. During Period 4, the recovery period, the lowest growth rates were found in the combined NCO2 and PCO2 treatment tanks (mean growth rates of 1.00 and 1.02 mg d-1, respectively). The highest growth rate among the treatments was again observed in the N treatment tanks (mean growth rate of 2.75 mg d-1). The mean growth rate in the Control tanks was 7.40 mg d-1 during this period. The results of this study demonstrate that increased levels of nitrate, phosphate, and pCO2 cause statistically significant decreases in the growth rate of A. cervicornis. The effects of nitrate and phosphate appear to be concentration dependent, and the effect of pCO2 is greater than that of nutrification. Therefore, continued eutrophication and projected pCO2 increases can be expected to have negative impacts on the survival and reef building potential of this species.

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.

  Link to NovaCat