"Marine mammals are providing early clues of our unseen impact on the sea," says Paul Sandifer, Chief Scientist for the new Oceans and Human Health Initiative in the US National Oceanic and Atmospheric Administration (NOAA). "There is mounting evidence that our activities on land are taking a toll on the health of the oceans, and in turn our own well-being."
"Wildlife can serve as a source of infection, as we have seen with the avian bird flu, but they can also be sentinels of pathogen pollution. They are often the first victims of these diseases," says Pat Conrad from the University of California at Davis. "By paying attention to them, it will tell us about our own health and the links between our health and that of the environment."
Cats and Otters: A Deadly Link to Land? When Pat Conrad first started studying the death of otters on the California coast, she had no idea that her investigation would lead her upstream. Her team traced the cause of death to the brain parasite, Toxoplasma, and ultimately to cats.
"Before I started this project I didn't think about things like how much cat feces gets in to the environment - how what we dump on our lawns and sidewalks flows into streams to rivers and into the ocean," says Conrad.
But with the discovery that otters in areas with heavy freshwater outflow are nearly three times as likely to be infected with Toxoplasma, and the fact that sea otters spend their entire lives grooming, sleeping, eating, and playing in the same nearshore waters where humans swim and surf, this land-sea connection is front and center.
Toxoplasma can also infect humans. It is the third most common cause of death due to food borne disease in the US: estimates indicate that up to 25% of the population may be infected with