Tinker & Estes Lab and Santa Cruz Field Station

Dynamics of infectious disease in near-shore marine environment

How do pathogen pollution and disease dynamics affect marine mammals in coastal California ecosystems?
What are the possible ramifications of sea lions serving as a new definitive host of T. gondii,
and how could this affect human health?

 

 

The southern sea otter is a keystone species in kelp forest communities, acting to increase the species diversity and providing ecosystem services. Despite federal protection since 1977, the southern sea otter population has struggled to recover and there are only an estimated 2,800 sea otters in California. A major factor contributing to the stagnant population growth rate is disease-related mortality in prime-aged adult sea otters. Infection with T. gondii has played a huge role in this mortality. Sea otters serve as the perfect sentinel for detection of coastal pathogen pollution because adult females are site-specific and otters consume some of the same food (e.g. abalone, mussels, clams) as humans.

To understand how pathogens that are deposited on land are transported to coastal waters, the UC Davis team is investigating the factors that govern the waterborne transmission of T. gondii oocysts(eggs, essentially). Based on previous research, it seems that domestic cats were a likely source of T. gondii in estuaries. Otters sampled in Estero Bay and near areas of highest freshwater runoff were found to be more likely to be exposed to T. gondii than otters sampled in other areas. In fact, detailed spatial tracking of individual sea otters led to the discovery that sea otters may be at highest risk near sea lion haul-out sites in sections of Estero Bay which has few freshwater inputs, thus bringing into question whether sea lions are serving as a new host for T. gondii.

Find Out What's Killing Sea Otters