Green sea turtles and dugongs are migratory marine mega-herbivores with a strong potential to aid in the dispersal and connectivity of their habitat, seagrass. Our research looked in to the role these marine mega-herbivores played in the dispersal of seagrass seeds to determine their importance in seagrass habitat connectivity. We found that these mega-herbivores are dispersing a large number of viable seagrass seeds for three different seagrass species, and that they are greatly enhancing the germination of seagrass seeds. However, our research also led to new questions about the dispersal and connectivity role these mega-herbivores are providing and their role in seagrass seed disease sterilisation. With green sea turtles listed as endangered, and dugong as vulnerable to extinction, a greater understanding on how they interact and impact their habitat is vital to ensure effective management and conservation, especially in a fast changing environment.