Estuaries Change Several Times a Day, and That Is What Keeps Them Healthy

An estuary is never the same from one hour to the next, and that is how it should be. Constant change is a necessary part of a healthy, working estuary.

The Rookery Bay National Estuarine Research Reserve, at the northern end of the Ten Thousand Islands on the gulf coast of Florida — one of the few remaining undisturbed mangrove estuaries in North America. Credit: NOAA.

What an estuary is

Estuaries and the wetlands around them are bodies of water usually found where rivers meet the sea. They are home to unique communities of plants and animals adapted to brackish water.

Driven by the tides

Estuaries run on the tides. Tides flush the system and deliver the nutrients that keep its food webs working. In doing so, they keep conditions changing all the time: the water level rises and falls several times a day, alternately exposing the estuary to the air and covering it with more water.

Built for change

The animals of an estuary cope well. Fish and crabs, for example, are mobile, and move around through the day as conditions shift.

Tides are not the only source of change. Weather patterns, the cycle of the seasons and climate change also affect conditions in estuaries.

Sources

Based on "Is change important to estuaries?" from NOAA's National Ocean Service, a work of the United States government in the public domain.