Integrated grazer management mediated by chemicals for sustainable cultivation of algae in open ponds

Several challenges need to be overcome for algal biofuels to become economically viable alternative to fossil fuels. The major bottleneck is that it requires continuous production of large quantities of algal biomass at a very low cost. To achieve this algal crops have to be stably cultivated round the year in open ponds at a sufficiently high density. Currently, it is highly difficult as algae crops cultivated in the open ponds are prone to numerous abiotic & biotic stresses, which lead to frequent culture crashes and productivity losses. Abiotic stress can be managed largely through bio prospecting, screening and selection of right kind of algal strains for that geographic location & season. Managing contaminants in open ponds along with maintaining productivity of algal crop to match the economics of biofuel production has so far proved to be an insurmountable barrier worldwide. The technologies successfully used till date to manage competition or grazing in open ponds have proved unsuccessful as these methods either limit desired productivity or are incompatible for prospective candidate algal strains ideal for fuel production. In the present study, we have taken a holistic approach starting from isolation, identification and characterization of major grazers associated with our algal crop and in parallel screening of several chemicals those could limit grazers in ponds. This was followed by testing the identified chemicals on the grazers, determining the sensitivity of our production strain to the chemicals found effective against grazers and finally providing chemistries that are able to eradicate the pests in open ponds with no adverse effects on our crop. Importantly this study reports 40 chemical candidates that are effective against grazers and can be utilized to prevent grazing during algae cultivation depending upon their compatibility with the algae strain grown.