Healthy Salt Marsh, Plum Island Estuary, Massachusetts (image) Marine Biological Laboratory Share Print E-Mail Caption Healthy salt marsh creeks at Plum Island Estuary, Massachusetts, are lined with lush, smooth cordgrass. The plant's below-ground roots and above-ground leaves build and maintain salt marshes. Credit David S. Johnson/MBL Usage Restrictions Please use with proper credit. Share Print E-Mail 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.