"Clear Lake", CA

We thought we’d step out of the car for a breath of fresh air and a nice view as we passed by Clear Lake on Highway 20 on our way up to the Mendocino National Forest in Northern California.  Little did we know the air was not so fresh!  A putrid mass of dead rotting algae clogged the entire shoreline.  I unfortunately made the assumption that this must be an invasive species of algae out of control in the lake, but a little research proved otherwise. 

Over one hundred years ago Clear Lake was described “…covered with a deep, dense moss, which sometimes rises to the surface, and often to such an extent in summer as to seriously obstruct the passage of boats through the water” and “the plants and moss from the bottom float in great quantities in the water, and it becomes unfit to drink” (Stone 1873).  It has been presumed that the “dense moss… that rises to the surface” is in fact noxious scum forming blue-green algae, also referred to as cyanobacteria.  While present in the lake for thousands of years, these species of noxious algae have increased sense the late 1920’s and especially sense the 1940’s, primarily due to increased erosion and nutrient loading from mining and land-use change around the lake (Richerson et al. 1994). 

These species of algae form “scums” because they form colonies of individual algae cells and some cells fill with gas and become buoyant to fix nitrogen from the atmosphere (Mioni et al. 2012).  (This is a really cool ecological trick utilizing bacteria, do web search on “nitrogen fixing bacteria” for more info).  Anyway, because these algal scums are gross they bother the residence of the lake and reduce tourism at a cost of millions of dollars a year (Richerson et al. 1994).   For more information a report was released earlier this year investigating cyanobacteria blooms in Clear Lake and the Sacramento-San Joaquin River (Mioni et al. 2012).  This whole exercise has really highlighted for me the danger in making assumptions with little data and how “naturally occurring” components of an ecosystem can become disruptive through the unconscious consequences of modern development. 

References

Mioni, Cecile, Raphail Kudela, Dolores Baxa, and Meghan Sullivan. 2012. Harmful Cyanobacteria Blooms and Their Toxins in Clear Lake and the Sacramento-San Joaquin Delta ( California ).

Richerson, Peter J, Thomas H Suchanek, Stephen J. Why, and Thomas Smythe. 1994. THE CAUSES AND CONTROL OF. http://www.des.ucdavis.edu/faculty/Richerson/CleanLakesReport1994.pdf.

Stone, Livingston. 1873. XX. -Report of Operations in California in 1873. http://www.co.lake.ca.us/Assets/WaterResources/Algae/Livingston+Stone.pdf.