UC San Diego

As increasing human demand and decreasing in global reserve, fossil fuel will no longer be able to sustain human energy usage in the near future. Algae based biofuel is an alternative energy source that has the potential to replace the demand of fossil fuel due to the high productivity and minimum land usage. However, considering the high cost, algae biofuel is not ready for practice in large industrial scale. Scientist put a lot of efforts on modifying algae genome to improve their productivity. But the ecological approach on create algae productive communities has been rarely practiced. In this study we tested how algae biomass productivity and resistance by grazers affected by algal species diversity. 11 different species of single celled algae were assigned into different combinations, and the changing in chlorophyll-α concentration and cell number for each treatment group has been recorded as the reference of cell productivity. Daphnia was introduced into the culture to test the ability to resist consumer grazing for each combination. There is no liner relationship among algae diversity, biomass productivity and resistance to Daphnia grazing. The biomass productivity and the ability to resist Daphnia grazing varies widely between combinations. Overyielding only been observed in some specific algae combinations. It is possible to reduce the cost of algae-based biofuel by creating a productive algae community. Extra effort is required to find the desired combination.