Between 2006 and 2018 - 80% of the 18.77km2 of seagrass in the Cocos Keeling Islands were lost due to multiple cascading pressures including dredging, unfavorable climate conditions and grazing pressure from green sea turtles. Since then, natural recovery has failed, principally due to sustained grazing pressure on remnant seagrass from the large green turtle population. By 2023, seagrass cover had declined to less than 1%, raising concerns about functional extinction and high levels of turtle mortality without intervention.
In response, a range of restoration approaches for the dominant seagrass Thalassia hemprichii were trialed during a 2 year study, including 3 shoot transplant methods and protection from herbivory pressure. Results found Thalassia could be successfully reestablished and have sustained expansion and growth through a range of shoot transplant approaches. Moreover, simple protection from grazing pressure at remnant seagrass areas could achieve similar results to transplanting. In 2024 this led the establishment the world’s first network of larger scale (20m x 20m) herbivory exclusion refuges. The aim of these exclosures is to deliver sanctuary from grazing pressure, facilitate seagrass recovery and provide seeds and vegetative propagules for future regeneration in the Cocos Island lagoon.