Oyster Reefs: Hard Workers Under the Water

Oyster Reefs: Hard Workers Under the Water

1Oysters do not look very busy. They have no legs or fins, and once a young oyster settles down, it stays in the same spot for the rest of its life. Yet many scientists say that oyster reefs are some of the hardest-working places along the coast. A reef forms when oysters grow on top of one another, year after year, in bays and other shallow, salty water. Here is a closer look at what these rough piles of shells do.

2First, oysters help keep the water clean. An oyster eats by pulling water into its shell. Inside, it traps tiny bits of food, along with some of the dirt floating in the water. Then it pushes the water back out, cleaner than before. One oyster can filter a large amount of water in a single day, and a reef can hold thousands of oysters working at the same time. In bays with healthy reefs, the water is often clearer, so sunlight can reach the plants growing on the bottom.

3Second, oyster reefs are homes for many other animals. The shells pile up into a hard, bumpy structure full of cracks and gaps. Small crabs, shrimp and young fish hide in these spaces, where bigger animals cannot easily reach them. Some small fish even lay their eggs inside empty oyster shells. Larger fish visit the reef to hunt, so one reef can feed and shelter many kinds of sea life.

4Third, reefs help protect the land. When waves roll toward the shore, they hit the reef first. The hard shells break up the waves and slow them down. As a result, the waves that reach land are smaller, and they wash away less sand and mud. Some coastal towns have built new reefs near their shores for this very reason.

5Sadly, many oyster reefs have disappeared. Over the years, people took too many oysters from the water, and pollution harmed others. Baby oysters need a hard place to settle, and old oyster shells are one of their favorite spots. So in some cities, restaurants now save the shells left over from meals. Volunteers clean the shells and let them dry in the sun. Then the shells go back into the water, where baby oysters can attach and grow.

6Cleaner water, safe homes and a protected shore are three strong reasons to care about oyster reefs. The next time you see an oyster shell, remember that it may once have been part of a busy underwater neighborhood.