Groundwater floating over seawater (IMAGE) University of Hawaii at Manoa Caption As cool, brackish groundwater discharges into the ocean it floats buoyantly on the surface, providing nutrient rich water that sustains primary productivity in coastal ecosystems. The floating groundwater plume is seen here as the clear layer of about 1 m in thickness underlain by murky ocean water. Credit Joseph Kennedy Usage Restrictions Image may only be used with appropriate caption and credit. License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.