The Salton Sea is a saline lake located centrally in the Colorado Desert, California. Salinity as well as nutrients of the Sea have been increasing since 1907, thus it is currently facing ecological collapse. The barnacle, Balanus amphitrite saltonensis at the Salton Sea was once thought to be a subspecies of B. amphitrite due to distinctive morphological differences between populations at the Sea and San Diego Bay. However, only one subspecies, Balanus amphitrite amphitrite, currently exists based on genetic studies. My study investigates physiological, survival, and morphological differences of B. amphitrite populations from the Salton Sea and San Diego Bay.

Weight-specific oxygen consumption rate was measured for 3 hours to compare respiratory responses of both populations at 18 experimental combinations of salinity (0, 15, 30, 36, 45, and 60 %o) and temperature (15, 25, and 35 °C). Although no overall significant difference in respiration occurred, significant differences between populations were found in 45 %o at 15 °C and in 0 %o at 35 °C. Salton Sea barnacles consumed more oxygen in higher salinities and at higher temperatures than San Diego Bay barnacles.

Results of survival experiments (T50) in the same 18 conditions for 48 hours • indicated that no animals died at 15 ° and 25 °C while animals tested in low salinities (0 and 15 %o) at 35 °C for both populations resulted in mortality of greater than 50 % of the treatment populations within 48 hours. Mortality rate showed that Salton Sea barnacles survived longer than San Diego Bay barnacles in low salinities at high temperature and that temperature had a greater influence on survival than salinity.

Morphological differences were examined by measuring animal diameter, height, and test thickness for both populations. Statistical analyses indicated that there were significant differences in those measurements between populations. Possibly as a result of phenotypic plasticity induced by different environmental conditions, external morphology is distinct between the populations.

Although B. amphitrite at the Salton Sea and San Diego Bay are the same species, Salton Sea barnacles may be adapted to tolerate the elevated conditions of salinity and temperature that occur in that environment.

LLU Discipline





School of Science and Technology

First Advisor

Stephen G. Dunbar

Second Advisor

Paul H. Buchheim

Third Advisor

David A. Hessinger

Degree Name

Master of Science (MS)

Degree Level


Year Degree Awarded


Date (Title Page)




Library of Congress/MESH Subject Headings

Barnacle -- Physiology; Barnacle -- Morphology; Marine ecology; Barnacles -- California -- Salton Sea; Barnacles -- California -- San Diego Bay; Salinity -- California -- Salton Sea.



Page Count

x; 109

Digital Format


Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.


Loma Linda University Electronic Theses and Dissertations

Collection Website



Loma Linda University. Del E. Webb Memorial Library. University Archives