Resistance of DISCOVR algae strains to deleterious species

The goal of the DISCOVR consortium is to improve the annualized areal production of open algal production systems through a process of algal strain evaluation and selection combined with testing in outdoor pilot scale production systems. The role of Sandia National Laboratories, in this evaluation process, has been to screen the selected subset of algal strains for resistance to grazing. Sandia tested 9 marine and 8 freshwater strains of algae against a panel of 14 grazer species, (5 marine, 5 freshwater and 4 euryhaline). A total of 153 algal/grazer pairs at two grazer concentrations for a total of 306 assays in triplicate. The relative resistance of each algal strain to each grazer strain was expressed as the decimal fraction of its specific growth rate 29in the presence of the grazer divided by the growth rate of the algae alone. Of the strains tested, those with the greatest resistance to the grazer panel were the freshwater strains Acutodesmus obliquus UTEX 393 and Scenedesmus obliquus. DOE 152z, and the marine strains Micractinium sp 14-F2 and Scenedesmus sp. 46B-D3. Additionally, these assays revealed the unexpected levels of variation in grazer resistance between taxonomically related organisms.