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Why Estuaries Are Important

Updated: May 9, 2023

By Jessica Brogna

When we think of effective ways to capture carbon, we often think of planting more trees. However, estuaries (also known as wetlands, marshes, and mangroves, just to name a few) are more effective than trees in capturing carbon dioxide. That is great but what is an estuary? According to the National Ocean and Atmospheric Administration (NOAA), “estuaries and their surrounding wetlands are bodies of water usually found where rivers meet the ocean.” Estuaries are unique and important ecosystems. The water in estuaries is called brackish, meaning that it has a mix of salt and freshwater from the combining of ocean water and water from rivers and streams. These habitats act as a home for many species, a breeding and nesting ground for many animals, and a stopover point for migrating birds. Some of the estuaries we have here in Orange County are Bolsa Chica, Upper Newport Bay, and San Joaquin.

Photo Courtesy by Jim Culp | Creative Commons

When it comes to carbon sequestration, estuaries are superstars! Each acre can store the carbon equivalent of the emissions from driving 7,000 miles according to to Restore America’s Estuaries! In fact, estuaries are more effective than trees at removing carbon from the atmosphere and storing it as something called blue carbon. NOAA defines blue carbon as, “carbon captured by the world's ocean and coastal ecosystems.” However, when these ecosystems are degraded, that carbon is released back into the atmosphere, thus making climate change even worse because when they hold a lot, they can release a lot. Carbon dioxide is known as a greenhouse gas and, although these gases are very important in our atmosphere because they absorb heat, in excess, they cause overheating.

Unfortunately, estuaries are threatened by human impact. One major impact affecting the health of estuaries is development and encroachment. In fact, here in Southern California, we have seen a significant decrease in the number of coastal habitats over the last couple of centuries. Since 1850, we have lost 48% of overall estuarine types, but some specific types of estuaries have seen more loss. According to the San Francisco Estuary Institute, vegetated wetlands have experienced the greatest loss in terms of area, whereas unvegetated wetlands have lost the most in proportion to overall wetland loss. As you can see in the picture below, what was the La Cienega wetland complex in the LA area was lost to urbanization, and is only one example of the many more we have lost. In addition, pollution, such as fertilizer runoff from agricultural areas, urban runoff, and waste are also major threats to these habitats.

Photo Courtesy by My Water Quality |

Now, what can we do to help? Environmentalism and advocacy start at home in our everyday maintenance and consumer habits. We can all be better about how we use and dispose of fertilizers, herbicides, and other toxic substances. These substances can seep and run off into our waterways, so make sure to read your products’ labels for disposal instructions. On a larger scale, you can join an environmental group that helps with conservation and habitat protection through restorations. In fact, OC Habitats and other local habitat conservation groups, host restoration events in local estuaries where invasive species and debris are removed to ensure that native plants have a place to thrive and support other species.

Because of how important these ecosystems are, we should devote more of our environmental activism and funds towards estuaries' conservation and restoration. To learn more about estuaries and to help make a difference, join OC Habitats during one of our monthly restoration events!

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