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Otter mystery plays on in Morro Bay

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Just a brief decade ago, the California sea otter population appeared to be on the road to recovery. Since 1985, the species had managed to climb from just more than 1,400 animals to slightly less than 2,400 a trend that encouraged coastal environmentalists. Then, without warning or reason, the progress halted.

The situation confounded conservationists in Morro Bay where otter death rates proved particularly high and prompted microbiologists to hunt for a cause.

A procession of theoretical suspects ranging from algae blooms to rodent parasites landed under investigation with inconclusive results. The latest in a series of potential culprits a protozoan known as Toxoplasma gondii, which emerged in 2002 offered enough evidence to survive the season. However, the debate continues regarding where exactly the parasite comes from and how to keep it out of the otters' habitat.

This topic co-headlined the Talk About the Bay forum on the afternoon of Sept. 2 in Morro Bay, along with Assemblyman Pedro Nava's (D-Santa Barbara) appeal to kill once-through cooling methods at coastal power plants. That issue will likely receive more local attention when LS Power finally begins modernization plans of the antiquated Morro Bay conventional steam facility.

Speaking on the toxoplasmosis outbreak among the otters, UC Davis researcher Haydee Dabritz offered a detailed explanation of how cats serve as a conduit between infected rodents and vulnerable sea life.

According to Dabritz, rodents infected with Toxoplasma gondii lose motor skills and become more susceptible to predators. When cats trap and consume infected animals, parasitic eggs shed in feline feces flush into the watershed during seasonal rains.

Surveying 294 Morro Bay, Cayucos, and Los Osos residents, researchers queried how many subjects either owned cats or fed strays. The results published July 1 in a leading veterinary journal numbered 7,284 domestic cats and as many as 2,000 more feral felines. That number of cats could generate roughly 107 tons of cat poop per year, nearly one percent of which is infected with a particularly resilient stage of the offending protozoan.

Abnormally high seroprevalence and mortality rates among the local sea otter population combined with the ease of tracking drainage sources in the relatively small watershed make Morro Bay a hotspot for toxoplasmosis research. Still, researchers hope to further analyze the effect of wild cats and opossums on the spread of the protozoan.

Some scientists, however, suspect a certain coastal relic's role in the eco-dilemma and, this time, it's not the power plant. The outmoded Morro Bay Wastewater Treatment Facility constructed in 1954 continues to raise eyebrows as, at least, a contributor to high levels of toxoplasmosis in Morro Bay. Cal Poly biologist Michael Black suggested that the city's wastewater treatment plant might emerge as a contributor in further studies.

"If that's the case, then, from the wastewater side of things, they don't want to know," Black said. "That means that something must be done. It involves money."

The plant is one of only a handful left in California still lagging behind Clean Water Act standards. According to plant administration, planners continue to labor over a modernization plan that should bring the facility up to code by March of 2014. However, public services division manager Bruce Keogh argued against the need for additional studies on a potential wastewater source of Toxoplasma gondii.

"There's no credible evidence that the plant is a source," Keogh said.

Morro Bay public services participated in a study with UC Davis researchers, in which mussels known to bioaccumulate the parasite were suspended in cages near the outfall and came out clean.

Still, local scientists claimed that the study erred by placing the baskets too high above the distributors, closer to the surface than the mussels' natural habitat.

"I'm not saying the plant is a definite source of toxoplasmosis, but we need to find out," Black said.

Additionally, the recent discovery of toxoplasmosis in sea lions, harbor seals, and even dolphins calls into question the notion that only mussels can bioaccumulate Toxoplasma gondii, since none of the above mammals actually feeds on the mollusk. Black and his researchers want to conduct tests using filter fish, like anchovies, to track the path of the pathogen through the marine food chain.

During the weekend conference where the otter topic reemerged several other issues also landed on the roundtable.

Assemblyman Nava identified offshore drilling, the danger of a terrorist strike on liquid natural gas storage facilities, and the eco-effects of once-through cooling as the three most troubling coastal dilemmas today.

Los Osos CSD president Lisa Schicker and Assemblyman Sam Blakeslee (R-SLO) addressed the role of collaboration in achieving wastewater solutions for everyone's favorite bedroom community. Regarding the same issue, engineering consultant Dana Ripley presented another rendition of his Ripley-Pacific's proposed effluent collection and treatment system.

Estuary program director Dan Berman offered an overview of the challenges facing the Morro Bay ecosystem Coastal Commission executive director Peter Douglas articulated on the need to locally buttress progressive policy and SLO mayoral candidate Christine Mulholland served as master of ceremonies.

 

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