The health and integrity of coral reef ecosystems are in decline worldwide due to an increasing suite of human activities, which threaten biodiversity and human wellbeing. One of the major drivers of coral reef ecosystem decline is poor water quality from human activities on land. Land-based pollutants from human activities travel downstream via watersheds - through groundwater flow and land areas drained by streams – and are funnelled into coastal environments. There is now ample evidence of the linkages between human activities in watersheds and elevated levels of pollutants in water discharged to coastal marine ecosystems. There is also a growing understanding of the myriad and often interacting impacts these pollutants have on coral reef ecosystems and the critical services they provide for associated dependent communities. This white paper reviews the linkages between landbased runoff and coral reef ecosystems, with four specific objectives to: (1) review how sediments, nutrients, chemicals, and pathogens affect corals and reef-associated organisms at a variety of life stages; (2) assess how these processes impact associated dependent human populations; (3) identify existing knowledge needs; and (4) provide science-based management options.
