• Estuaries are some of the most productive ecosystems in the world.
• Estuaries can have many different types of habitat. Some common estuarine habitats are: the water column, oyster reefs, coral reefs, kelp and other macroalgae, rocky shores and bottoms, soft shores and bottom, submerged aquatic vegetation, coastal marshes, mangroves, deepwater swamps and riverine forests. 
• Estuaries can also be divided into tidal zones (supratidal, intertidal and subtidal zone) subject to changing water levels, temperature, oxygen content and levels of light.
• Energy is cycled through the estuarine food web from producers and autotrophs to consumers and decomposers.
• Invasive species are those that do not naturally live in an estuary, but were introduced, often accidentally, by humans. Invasive species compete with native plants and animals for shelter and food and weaken the ecosystem.

What to Learn More?

1. Productive Ecosystems
2. Estuarine Habitats
   • Coastal Marshes In Depth
   • Mangroves In Depth
3. Tidal Zones
4. Cycle of Life
5. Unwanted Visitors 
6. Fish fact sheets on a select group of Endangered Species and Species of Concern who make their home in an estuary