Life in an estuary

What are estuaries?

Many different types of plant and animal communities call estuaries home because their waters are typically brackish — a mixture of fresh water draining from the land and salty seawater. This unique combination of salty and fresh water creates a variety of habitats. Some common estuarine habitats are oyster reefs, kelp forests, rocky and soft shorelines, submerged aquatic vegetation, coastal marshes, mangroves, deepwater swamps, and riparian forests. With so many places to live and so many niches to fill it is no wonder why estuaries are some of the most productive ecosystems in the world.

A great egret feeding in a marsh located along the Chesapeake Bay in Virginia. The Chesapeake Bay is the largest estuary in the U.S. and is one of the most productive bodies of water in the world.
Do your part: Help protect our estuaries
Think before you pour something down the drain. Many hazardous products flow from household drains through sewage treatment plants and into coastal bodies of water...

Importance of estuaries

Estuaries are very important to the lives of many animal species. They are often called the “nurseries of the sea” because numerous animal species rely on estuaries for nesting and breeding. Most of the fish and shellfish eaten in the United States, including salmon, herring, and oysters, complete at least part of their life cycles in estuaries. Besides being a source for food, humans also rely on estuaries for recreation, jobs, and even our homes. A majority of the world’s largest cities are located on estuaries. This can be both a good and a bad thing. Estuaries filter out sediments and pollutants from rivers and streams before they flow into the ocean, providing cleaner waters for humans and marine life. However, coastal development, introduction of invasive species, overfishing, dams, and global climate change have led to a decline in the health of estuaries.

Andrew Tokuda, Global environmental science major at University of Hawaiʻi at Mānoa and 2018 NOAA Hollings scholar, holds a chum salmon while kneeling beside the Tutka Bay estuary. Tokuda interned at the Kachemak Bay National Estuarine Research Reserve in Homer, Alaska, in summer 2019.
NOAA scholars share stories of working in an estuary
From the inspiring to the unexpected, 12 undergraduate scholars share what surprised them most about spending a summer in an estuary.

Estuary stewardship

Ensuring the health of our estuaries is vital to the survival of the plant and animal communities that call them home and the humans that depend on them for their way of life. To preserve our estuaries, the National Estuarine Research Reserve System was established to protect more than 1.3 million acres of estuarine habitat for long-term research, monitoring, education, and stewardship throughout the coastal United States. However, you can also help protect estuaries at your home by planting native plants, using fertilizers sparingly, and cleaning up after your pets.

During the 2018 Rivers2Lake Summer Institute, Superior Middle School life science teacher Valerie Poynter (left) and Carlton High School biology teacher Katherine Nistler (right), accompanied by University of Minnesota, Duluth, Ph.D. student Kait Reinl (center), perform a plankton tow in the Bibon Slough in Port Wing, Wisconsin.
Teachers engage year-round with Lake Superior
From tracking lake sturgeon and sampling cyanobacteria to monitoring water quality, they were immersed in the science and conservation of Lake Superior, the town’s namesake and the largest surface of freshwater in the world.


Education also plays an important role in protecting our estuaries. An estuarine literate person understands the interconnectedness and interdependency of estuarine systems with other earth system in both time and space, can communicate about estuaries in a meaningful way, and is able to make scientifically informed and responsible decisions regarding estuaries and coastal areas. To create an estuarine literate society, the National Estuarine Research Reserve System has developed six estuarine principles and concepts. Educators can use this framework to build lessons and curricula that will teach their students the importance of estuaries and what they can do to help protect them.

Updated February 2019