What do pumpkins and shells have in common? Both of them can be found on the beach! I have marveled at a pumpkin-strewn beach in Pescadero on several late fall visits. When I see orange globes bobbing in the surf I am always impressed and reminded at how connected we truly are to the ocean. Eventually, all of our water makes its way to the ocean. From the top of Sierra Nevada, through rural areas and dense cities, every drop of water has quite a journey; and as with all journeys, along the way they pick up a thing or two.
Point source pollution comes from an identifiable source such as a sewage or industrial plant. These sources of pollution can often be regulated and monitored for their impact. Non-point source pollution is more diffuse and mostly comes from run off of water from cities, suburbs, and farms. This type of pollution can have a huge effect on the ocean.
Runoff can carry all sorts of things into the water. Coastal stewards may be able to pick up the trash, but there is so much more that we cannot even see. In addition to pesticides and other chemicals, nutrients such as nitrates and phosphates wash from farms and factories. They are found in detergents and also in fertilizers.
Just as fertilizers help plants to grow on land, they encourage growth in the water as well. While this might sound good, and unnatural bloom of algae can cause a cascade of effects in an ecosystem. An unusual bloom of harmful algae, often called a red or brown tide, can put toxins in the water. Blooms can also rob the water of oxygen as the algae metabolize and as the bacteria subsequently break down the dying algae, resulting in “dead zones”.
Stewards have yet another opportunity to help the ocean in the grocery store. Many people choose to eat organic foods from farms that do not use chemicals on the plants (that eventually join the watershed). Different styles of farms also contribute different amounts of run off and pollution. With a little bit of research, you can learn about your local farms and what they do to keep the water clean.
“Ocean ecosystems plagued by agricultural runoff” http://news.stanford.edu/news/2005/march16/gulf-030905.html
EPA: Agriculture http://water.epa.gov/polwaste/nps/agriculture.cfm
EPA: Polluted Runoff: Nonpoint Source Pollution (and Things You Can Do) http://water.epa.gov/polwaste/nps/