A case study for the Whitsundays Plan of Management assessed cumulative impacts for coral reef ecosystems in the GBR, and included reefs surrounding Hayman, Arkhurst, Langford, Black, Bird and Hook Isles. Assessed pressures included coral bleaching, cyclonic storms and COTS outbreaks; and impacts from boat anchor damage, recreational fishing, and fin damage from snorkelling and scuba diving. An ecosystem model represented the direct effects of pressures, with the model validated against observed responses of reef biota in the assessment area following Severe Tropical Cyclone Debbie in 2017. Model predictions found impacts from recreational use alone ranged from relatively low levels of likelihood where use and activity levels are most restricted, to relatively high where use and activities levels were greatest. The inclusion of climate change and COTS outbreaks dramatically increased the likelihood that reef values could be diminished throughout a majority of the area of assessment.