Tumors in Fish from Morro Bay Point to Contaminants
Arrow gobies from Morro Bay with tumors. Credit: Lars Tomanek.
Related Information
Researcher:
Lars Tomanek
Biological Sciences Department
California Polytechnic State University
T: 805-756-2437
E: ltomanek@calpoly.edu
Relevant Links:
Cal Poly Environmental Proteomics Laboratory
Revised:
April 24, 2008
April 25, 2008
Contact: Christina S. Johnson, 858-822-5334, csjohnson@ucsd.edu
California Sea Grant has awarded a one-year, $30,000 grant to a Cal Poly biologist to investigate the cause of cancerous tumors in arrow goby fish from Morro Bay.
The grant’s recipient, biology professor Lars Tomanek, believes the tumors, which can be as large as the fish’s liver, are being caused by endocrine disrupting contaminants in the bay.
In dissections of 150 fish collected from mudflats in the bay, about 8 percent had large gonadal tumors, Tomanek said.
A subsequent histological analysis of 12 fish, led by researcher Swee The in the School of Veterinary Medicine at UC Davis, revealed that even the apparently healthy fish, sent in as control specimens, had abnormal liver cell growth, indicative of early stages of liver cancer.
Another 250 arrow gobies were collected from the bay and tested for 40 common persistent organic pollutants (POPs) — toxins that accumulate in the environment. The livers of these fish were found to contain relatively high levels of nonylphenol, which is the break down product of nonylphenol ethoxylates, compounds added to industrial and household detergents to help break apart oil and grease. Nonylphenol ethoxylates are banned in Europe.
Arrow gobies are small, 2-inch long, bottom dwellers that seek protection from predators by occupying ghost and mud shrimp burrows. The fish are abundant in mudflats in Morro Bay, and they are year-round bay residents. These characteristics make the goby a natural species for studying the bay's ecological health.
The goal of the Sea Grant project will be to use proteomics to investigate whether there is a causal link between nonylphenol and tumor growth. In laboratory experiments, fish will be exposed to varying levels of POP contamination and their subsequent responses, as measured via protein expression, will be studied and compared to that of fish collected in the wild.
Morro Bay is considered a relatively uncontaminated waterway and current environmental testing in the bay has not revealed high levels of POPs in either the water or sediments, Tomanek said. High levels of PCBs, DDTs and PBDEs have, however, been detected in Central Coast sand crabs and adipose (fat) of sea otters.
POPs exist in very low levels in the water. "The goby data suggests that existing water testing is overlooking pollutants that exert detrimental effects on marine organisms in the estuary," Tomanek said. "Proteins are an ideal indicator of the physiological state of an organism to evaluate the biological impact of POPs."
Tomanek is a member of the San Luis Obispo Science and Ecosystem Alliance (SLOSEA), a partnership of scientists, resource managers and stakeholders to improve the health and management of Morro Bay. He presented his preliminary research on arrow goby tumor rates at a February SLOSEA advisory committee meeting. (Cal Poly biology professor Dean Wendt is SLOSEA's Program Director.)
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