By Erik Vance
Anyone who lives near the Bay or walks along the shoreline knows the land and water share a constant connection of give and take. Sediment flows from the mountains, through the marsh, into the Bay. Meanwhile, salmon go exactly the opposite direction, bringing a little of the open ocean into Sierra foothills.
It turns out that this link is even tighter than anyone had ever guessed. Scientists at the University of California Davis recently did a series of tests to see how easily diseases can transfer from land to water. They were looking at a particularly nasty bug, called Toxoplasma gondii, which for decades has decimated populations of sea otters up and down the West Coast by burrowing into their brains and causing what amounts to a lethal flu.
The disease is often carried by housecats and is spread through microscopic eggs in their droppings. But it’s not just sea otters that worry about the tiny critters. T. gondii is a microscopic protozoan (like the creatures that cause a red tide) that can strike any warm blooded animal. Pregnant women must be especially careful, as it can be lethal for a developing fetus.
While currently no vaccine exists, the Davis scientists seem to have discovered the next best thing: wetlands outside your back door. The team dropped some closely-related (though harmless) protozoa into the water along the shoreline, both in places with lush wetlands and in places with none. Then they waited to see what came out the other side into the water.
The results were shocking. It turns out wetlands literally eradicate T. gondii. In fact, every 30 feet of wetland between the shore and water provided 100 times more protection. A thick, healthy wetland was a whopping one million times better at blocking the pathogen from getting into the water than areas with no marsh at all.
Scientists have known for some time that wetlands can absorb heavy metals, poisons, and even sewage–releasing healthy, clean water (and on the Gulf Coast they even absorb the odd hurricane). However, this study shows that wetlands have been doing the same thing for dangerous diseases and we never knew it. Think of them as nature’s soap and water.
This would be good news, except for the fact that 95% of the Bay’s wetlands have been diked or drained since Europeans arrived on the scene. The few remaining wetlands are constantly fighting off attempts to turn them into parking lots or bayside condos.
That’s why now, more than ever, we must work together to protect and restore our wild shorelines. Not only to preserve the precious connection between land and water, but also to promote a healthy and disease-free environment for Bay Area communities and wildlife.