By Philip M. Orton, Stevens Institute of Technology, and Stefan Talke, California Polytechnic State University Centuries ago, estuaries around the world were teeming with birds and turbulent with schools of fish, their marshlands and endless tracts of channels melting into the gray-blue horizon. Fast-forward to today, and in estuaries such as New York Harbor, San Francisco Bay and Miami’s Biscayne Bay – areas where rivers meet the sea – 80% to 90% of this habitat has been built over.