St. Johns River Water Management District St. Johns River Water Management District St. Johns River Water Management District St. Johns River Water Management District St. Johns River Water Management District St. Johns River Water Management District
St. Johns River Water Management District -

STEM and education

Oyster mats — Homes for my friends

Do you like seafood? If so, try to imagine that the Indian River Lagoon is a huge seafood market, offering all kinds of delicious fish, crabs, shrimps, clams and oysters.

Humans have always depended on the lagoon for food, but humans can impact the lagoon in ways that can harm the food sources they prize. Consider the humble oyster, a tasty shellfish that lives on the bottom of the lagoon. Oysters can be cooked several different ways and can even be eaten raw. We snook don’t like them, but I hear that people find them tasty.

Beside making a good meal, oysters play an important role in keeping the lagoon clean and healthy. Oysters are filter-feeders: they draw water in over their gills through the beating of tiny, hair-like cilia (pronounced silly-ah). One adult oyster can filter about three gallons of water every hour, screening out tiny plankton and suspended particles that provide the oyster with food. Food gets trapped in the mucus on the gills, and is transported to the mouth, where it is eaten and digested. Think about how much water all the oysters in the lagoon can filter every hour. That’s a lot of cleaning up!

The oyster’s greatest predators include crabs, sea birds, some types of snails and humans. At one time, oysters were plentiful in the lagoon. There were so many that Native Americans who lived near the lagoon would eat them by the thousands and pile the empty shells so high that they looked like hills. These garbage mounds are called shell middens and several of them can still be visited today.

Times have changed. Pollution, overharvesting and the damaging waves caused by boat traffic have reduced the number of oysters in the lagoon significantly.

But there is good news. Many volunteer groups, agencies, universities and others are leading projects to help save the oysters and rebuild oyster reefs throughout the Indian River Lagoon.

Children and adults are helping to make special mats that serve as the building blocks for new oyster reefs. Oyster shells are drilled and then attached to each mat. As the mats are finished, they are joined together and weighted down to help hold them in place. They are then placed over dead areas in oyster reefs to encourage new oysters to move in and settle down.

Scientists have learned that oyster shells release a chemical signal that tells floating oyster larvae where it’s safe to land and grow. The mats help to increase oyster growth and, over time, will help to rebuild many of the oyster reefs that have been lost. As new oyster reefs become established, other wildlife that depend on the reefs to survive will also return to repopulate damaged areas.


In this section
More about


Governing Board meetings
Please see agendas for specific meeting times, which may differ monthly.

Lobbyist registration requirements

Other district meetings and notices

Central Florida Water Initiative

Tell us how
we are doing.

Take our survey on
customer service.

By accessing this site, you agree to accept terms and conditions of the district’s liability disclaimer.

Employee Portal

St. Johns River Water Management District
4049 Reid Street, Palatka, FL 32177
(800) 725-5922