Why our estuaries are important

Mangrove island in the Indian River Lagoon. PHOTO CREDIT: Florida Oceanographic Society.

By Ted Lukacs

It is relatively easy to address the issues concerning popular game fish species experiencing problems from overfishing. Fisherman readily support catch limits and practice proper catch and release techniques. But it’s hard to get enthused about estuaries, maybe because the issues are less clear and the answers more complicated. In fact, what exactly is an estuary? Officially, it is a partially enclosed body of water along the coast where fresh water from rivers and streams mixes with salt water from the ocean. Notable estuaries include Mobile Bay, Chesapeake Bay, San Francisco Bay, Tampa Bay, New York Harbor, Long Island Sound, Puget Sound, and our own Indian River Lagoon. The reality is that more than 20% of the world’s largest cities are located on estuaries.

It is impossible to overstate the importance of estuaries. They are home to enormous numbers of animals and plants— the Indian River Lagoon, for example, is the most bio diverse estuary in North America, home to greater than 3,000 different species of animals, plants and planktonic species. Estuaries are nurseries for young fish that hide in the sea grass beds and feed on invertebrates and smaller fish. Some 75% of all fish caught commercially spend at least part of their lives in an estuary; 80-85% of all recreationally-caught fish spend all or part of their lives in an estuary. The fishing industry is a 111 billion dollar per year business making the importance of estuaries to sport and commercial fishing critical.

Estuaries filter out sediments and pollutants carried from upland waterways, helping to provide cleaner water for people and marine life. Plants in estuaries retard erosion. Estuaries protect inland areas from flooding by absorbing storm water before it can reach upland areas. And estuaries are often places of great natural beauty. You can stand on a dock in the Indian River Lagoon on a quiet summer morning, and see wood storks roosting in a nearby mangrove tree; the odd pelican looking for breakfast; sea grass beds waving in the slight current; watch a school of bay anchovies darting; and, see mullet break the surface. It is hard not to feel connected and at peace.

Unfortunately, estuaries are under siege from a variety of threats. Many have been filled in and developed. Dams block the natural routes of rivers and cut freshwater off from estuaries. Diversion of water for food control into estuaries can have different but similar ill effects. Sediment from soil erosion caused by deforestation and poor farming practices can choke waterways. Contamination from fertilizer runoff, industrial runoff, sewage, and farm animal waste is a major problem. Some of these pollutants linger permanently, and accumulate. Some find their way into the fish that inhabit estuaries, in some cases rendering them unfit to eat. Worldwide the effects of pollution are being felt – it was the industrial pollution in China and Russia that ruined fish stocks in the Amur River.

There are no easy answers to these problems. We can fight further attempts to fill in estuarine areas, but projects like dams and ood control serve human needs. Deforestation clears land for housing and development and with the human population now at more than 7 billion, pressures will continue to increase. Modern seed stocks are engineered for greater yield to feed populations, but require application of chemical fertilizers. Industrial activity cannot be completely pollutionfree, so industrial pollutants will continue to accumulate in estuary waters. The issues that affect estuaries, like most in modern society, are complex and not easily addressed. Unless we find solutions, our estuaries and the fish that live in them will be at risk.

Ted Lukacs is a volunteer writer for the Florida Oceanographic Society

Florida Oceanographic Society
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Florida Oceanographic Society’s mission is to inspire environmental stewardship of Florida’s coastal ecosystems through education and research.