Seagrass meadows are highly productive ecosystems that sequester large organic carbon stocks and play an important role in nutrient cycling in oligotrophic habitats. Shark Bay/Gathaagudu represents one of the world’s largest seagrass ecosystems and contains 1.3 % of the total C sequestered within the top metre of seagrass sediments worldwide. However, rising marine temperatures and the increasing frequency of marine heatwaves poses a significant threat to the resilience of temperate seagrasses Amphibolis antarctica and Posidonia australis in this ecosystem. I will investigate the contribution of seagrass to historical carbon and nutrient budgets in Shark Bay/Gathaagudu using stable isotope techniques. This data will help to predict how future climate change will affect ecosystem functions and services and will identify areas of conservation importance.