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

Andrew Rogerson

Second Advisor

Charles G. Messing

Third Advisor

Patricia Blackwelder


The current study examines salinity tolerance in naked amoebae. A biodiversity study was conducted in the Salton Sea, an inland lake in southern California, with an average salinity of 44 ‰. Amoebae were also collected from hypersaline ponds around the perimeter of the Sea where salinities averaged 160 ‰. A total of 45 species of amoebae were isolated, about one third of which were new to science. One Salton Sea species, Platyamoeba pseudovannellida n.sp. was found to survived over the range 0 - 150 ‰. A first estimate of abundances of amoebae in the Sea showed that densities could reach 237,120 cells L-1. Many of the isolates were observed to consume cyanobacteria and algae suggesting that amoebae are important regulators of blooms in the Sea, although this was not tested experimentally. Samples from the intertidal zone of a beach, a habitat also subject to salinity fluctuations, provided the first abundances of naked amoebae in sand. Densities ranged between 181 and 8473 amoebae cm-3, again suggesting that amoebae are important micrograzers in this challenging environment. From the aforementioned studies, 6 clones of amoebae were isolated for salinity tolerance experiments (2 marine beach isolates, 2 Salton Sea isolates, and 2 hypersaline pond isolates). A seventh clone, Acanthamoeba polyphaga, a common freshwater/soil amoeba was obtained from the Culture Collection of Algae and Protozoa (CCAP). The experiments compared the effects of gradual versus no acclimatization and used growth rate and culture yield as indices of effect. Generally, amoebae were tolerant over a wide range of salinity conditions and were not markedly influenced by pre-conditioning to salinity regimes. Acanthamoeba grew in 0 -12 ‰, marine clones 2 and 3 in 0 - 110 ‰, Salton Sea clones 4 and 5 in 0 - 150 ‰, and the hypersaline clones 6 and 7 in 0 - 270 ‰ salt. The results suggest that most amoebae are essentially unaffected in terms of growth and yield by moderate and severe salinity changes. The survival and activity of large populations of amoebae in sites subject to salinity challenges suggest that they should be considered in future studies designed to understand their as yet undefined ecological role.

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