Resistance and Resilience of Marine Microalgae in Poly-Versus Monocultures in Response to Salinity Stress

In the global search for renewable resources and clean fuel, algae-based biodiesel has growing interest due to a high yield of oil production by mass. Biodiesel can be synthesized from the lipids produced by the fast growing microalgae.  Recent studies have found a higher biomass and productivity in algae polycultures compared to monocultures due to a disturbance by a rotifer (biological disturbance).  Here, we investigate whether an environmental disturbance (increase in salinity) will also allow polycultures to be more resistant to the disturbance and recover faster after this disturbance.  We grew monocultures and polycultures (2- and 3-species treatments) of three different algae species (Nannochloropsis salina, Dunaliella tertiolecta and Tetraselmis suecica) in 200 mL algae media.  After growing for two days, we exposed all treatments to over 100 ppt salinity for two days and then reduced salinity levels to pre-stress salinity conditions of 34 ppt.  We found that resistance to salinity shock treatment is dependent on algae species and that polycultures in general had an increased capability to recover after increased salinity.