Sediments damaging reef Sediment being washed into the ocean from rivers is continuing to damage the Great Barrier Reef and is having a more widespread impact than scientists first thought. The Australian Institute of Marine Science (AIMS) has led the study of 10 years worth of satellite data. The study focused on run-off from the Burdekin River. The study shows that large river flood events during the wet season are washing sediment into the ocean, which is having a significant impact on water quality around the reef. The sediment reaches far off the coast and lasts several months. Sediment is one of the biggest pressures on the health of inshore reefs. It clouds the water and blocks sunlight from reaching the photosynthetic algae that gives coral its vibrant colours. The algae depends on the sun to survive. It can also kill or damage sea grasses, which are important food for mammals and fish because they also need the sun to survive. The study showed that water clarity was affected not only in the inshore area, but actually at a lower level it was visible quite a way off shore. Modelling studies show the amount of sediment in the water has increased significantly since human settlement and the beginning of agricultural activities. Other factors blamed include wastewater and stormwater run-off and more industry and other coastal development. The new research into the impact of river run-off has led to renewed calls for better land management practices. Work on reducing the amount of sediment entering the ocean has already begun.