Another submerged habitat found in Mobile Bay are Oyster Reefs. Oyster reefs are composed of animals that don't depend directly on sunlight. Oysters depend on food-carrying currents but, not water depth. The reefs tend to form wherever a hard bottom and sufficient current exist. Oyster reefs are most successful where the bottom currents carry sediments away from the reef.
Oysters are bio-indicators of an estuary.
In other words, they can tell us about the water quality in Mobile Bay. Oysters eat by filtering, or straining, organisms out of the water. They are known as filter-feeders. Heavy rains cause stormwater runoff into the Bay. The stormwater usually carries pollutants which end up, directly or indirectly, in the bay.