Abstract of the manuscript to which this dataset belongs to: "1. Our knowledge of the functional role of large herbivores is rapidly expanding, and the impact of grazing on species co-existence and non-native species expansion has been studied across ecosystems. However, experimental data on large grazer impacts on plant invasion in aquatic ecosystems are lacking. 2. Since its introduction in 2002, the seagrass species Halophila stipulacea has rapidly expanded across the Eastern Caribbean, forming dense meadows in green turtle (Chelonia mydas) foraging areas. We investigate the changes in seagrass species co-existence and the impacts of leaf grazing by green turtles on non-native seagrass expansion in Lac Bay (Bonaire, Caribbean Netherlands). 3. Green turtle grazing behavior changed after the introduction of non-native seagrass to Lac Bay in 2010. Field observations, together with time-lapse satellite images over the last four decades, showed initiation of new grazing patches (65 ha, an increase of …