Our love hate relationship with algae

We often get mixed messages in the media about algae. I was thinking about this yesterday, while introducing my students to the role algae play in global biogeochemical cycles. Algae are the heroes of the planet I told them. This wisdom could be considered a euphemism for those that want to see the world from a plant centric view and are used to thinking about algae as stinky pond scum. I think the statement is quite accurate and was passed down from my graduate school adviser, who was sure it was one of the first things he told his students. So I told my students how things considered algae (see http://algaeenergy.blogspot.com/2010/03/what-are-algae.html ) are responsible for the oxygen in the atmosphere because oxygen is a biproduct photosynthesis. I also told them how micrscopic algae were mostly responsible for controlling the carbon cycle on the planet through a process called the biological pump.

This is a intricate cycle occurring in the oceans, where there is a balance between photosynthetic organisms (algae) producing biomass and oxygen from carbon dioxide and water, and heterotrophic organisms who eat the algae and breath off carbon dioxide. If this cycle was perfect, then carbon dioxide and oxygen would stay in steady state in the atmosphere through time, and the atmosphere would have never oxygenated, because each time oxygen was produced, it would have been consumed. Luckily, the biological pump is leaky pump, and some of the algae biomass that derived from carbon dioxide in the environment is "fixed" it into organic molecules that can sink out of the system and gets buried on the ocean floor. This buried organic carbon - when buried in high quantities - eventually becomes oil and natural gas over millions of years.

So this is a simplified description of a complicated process but it demonstrates that yes, algae are our heros! Thanks algae for the oxygen, and for sequestering carbon at a continual rate, and for sourcing the petroleum that makes our world run.

But then I talked to my students about dead zones. We learned how nutrient run off from rivers causes algal blooms. Nitrogen and phosphorous work to fertilize the plant on land - specifically the crop that produce affordable food - and they also work to fertilize algae once the excess reaches lakes and oceans. When the algae bloom as a result of the nutrient addition, they are quickly eaten by other things like protist, zooplankton and bacteria, that turn all that carbon that is now in the form on algae biomass back to carbon dioxide. In the process, the heterotrophs use up all the oxygen produced by the photosynthesis in the bloom and then some. Because the fresh water from the rivers floats on top of the sea water - called a lens - its hard for the oxygen in the atmosphere to penetrate the lens and the bottom waters remain oxygen poor. Thus a dead zone forms and animals that move leave, and animals that can't die. In this case algae get a bad rap. Algae also are put in the villain role when the group that blooms is a toxin producing bloom which seems to becoming more frequent.

So there you go, in one case algae are the heroes, on the other they are the villains. As I have watched the development of the algae biofuels industry in the past few years, it appears that this little critters play both parts in this sector. On one hand, people sing the praises of algae, preach about their potential as high lipid producers, remind us that they can grow on waste water and won't compete with food for arable land. This is all true. But then we hear frustration that none of the companies can produce high quantities of biomass and the cheep way to produce algae biomass in bulk doesn't work well(ponds) and the more expensive way (photobioreactors) is too expensive, and in general it is taking a long time to figure it out. This is true too, and thus algae have gotten a bad rap again. As I mentioned in a previous post, I think overcoming the challenges to using algae as a feedstock for energy production will just take a bit more time and patience than using something like corn or soybeans where we know just about what ever gene in their genome does under various physiological conditions or we will know soon (see a post about updates on genomics of energy grops from the JGI meeting (http://redgreenandblue.org/2010/03/30/the-genetics-of-fighting-climate-change-part-1/#more-3777). The state of algae genomics is just not in that place, but the academic community and industry are moving forward at a rapid pace. Just because they are small, doesn't mean that they are simple. Its rare to find a jack of all trades and a master of all too. Algae, are a sort of organismal jack of all trades, and they are already the master of a number of global processes.