Xiao Li Ma


Two intertidal invertebrate species, M galloprovincialis and Balanus glandula, were collected from seven different bay sites along the Southern California coast to test if environmental contamination is associated with the decrease of genetic diversity at the population level. Collections were made at three relatively pristine "clean" sites and four "impacted" sites which were exposed to heavy industrial or boating activity and which had previously, been identified as having measurable levels of pollution. The "Comet" assay (Single Cell Gel electrophoresis) was performed to measure single-strand DNA breaks in mussels at several of the sites in order to confirm differing impacts of pollution on the animals at the different sites. In this assay, cells in impacted populations with increased DNA damage displayed increased migration from the nuclear region towards the anode during electrophoresis. Genetic diversity at the different sites was assessed by comparing fragment polymorphisms generated from genomic DNA by RAPD-PCR (Randomly Amplified Polymorphic DNA - Polymerase Chain Reaction). All populations exhibited a large amount of genetic diversity and were genetically similar to each other. However, several different measures of diversity indicated that for most primers, the populations of both species from impacted sites had lower genetic diversity compared to populations from clean sites. Individuals at impacted sites were more likely to share the same haplotypes than were those from clean sites. Few bands seen in the clean populations were absent from the impacted populations or vice versa, but a number of bands which were common in the clean site populations were significantly less common in the impacted populations. Together, these results suggest that pollution at the impacted sites may act as a selection force decreasing genetic diversity among the resident invertebrate populations.

LLU Discipline





Graduate School

First Advisor

David L. Cowles

Second Advisor

Leonard Brand

Third Advisor

Ronald L. Carter

Fourth Advisor

E. Clifford Herrmann

Fifth Advisor

George T. Javor

Degree Name

Doctor of Philosophy (PhD)

Degree Level


Year Degree Awarded


Date (Title Page)




Library of Congress/MESH Subject Headings

Variation (Biology) -- Effect of pollution on -- Southern California Bight (Calif. and Mexico); Mytilus galloprovincialis -- Effect of pollution on; Balanidae -- Effect of pollution on; ntertidal ecology -- Southern California Bight (Calif. and Mexico).



Page Count

ix; 141

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