1. Experimental risk assessment for dispersal, invasion, and impact on wild algae of genetically-modified Scenedesmus dimorphus UCSD Shovon Mandal Nathan Schoepp Jonathan Shurin Steven Mayfield Michael Burkart Ryan Stewart Steven Villareal Sapphire Energy Shawn Szyjka Yan Poon Briana Niessen

2. Synthetic biology to improve algae biofuel feedstocks: What are the risks to native ecosystems?

3. Three stages of invasion: dispersal, establishment, impact

6. Measuring dispersal

7. > > Distance: P=0.0003 Distance*direction: P=0.004

8. Measuring dispersal > >

9. Measuring colonization in native plankton

10. Population grows in all lakes regardless of starting density r (day -1 ) GM WT Initial density (cells/ml) Lake: P<0.001 Density: P<0.001 Lake*density: P=0.01

11. Measuring impact Does invasion affect diversity, composition or biomass of native algal species?

12. No effect of GMO on algal biomass Lake: P<0.0001 Treatment: P<0.0001 Date: P=0.0003 Lake*treatment: P=0.02

13. No effects on native diversity Lake: P<0.0001 Lake*treatment: P=0.06

14. No effects on native species composition Productive lakes Unproductive lakes Scenedesmus addition

15. Conditions for spread of GMO algae Dispersal GM Scenedesmus colonize tanks up to 50m from raceway Dispersal rate declines with distance from source

16. Conditions for spread of GMO algae Dispersal Invasion GM and Wild-type Scenedesmus populations grow in lake water with native plankton communities at any starting density

17. Conditions for spread of GMO algae Dispersal Invasion xImpact No apparent effects on biomass, diversity or composition of native algae

18. What risks do GMO algae pose to native ecosystems? Modified or unmodified algae are likely to disperse from cultivation and colonize natural water bodies GM Scenedesmus is ecologically indistinguishable from WT in its impact on native ecosystems