Laboratory testing protocol for the impact of dispersed petrochemicals on seagrass

► Seagrass were exposed to dispersed and non-dispersed crude and fuel oil. ► Dispersed oil led to significant reductions in photosynthetic health of seagrass. ► Non-dispersed oil resulted in only minor reductions in seagrass health. ► Testing protocol developed enables rapid comparisons of oil spill mitigation options.