Besides being an aphrodisiac? Aside from being a huge part of MD. & VA. history it was also a big $ maker. Sadly like most things man touches we almost killed the entire oyster industry along with the clam, blue claw crab, Rock & even eel via pollution & over fishing. The oysters & clams are are filters, they keep the water clean , provide a food source for the other animals & for man. Fortunately over the last 25 years the DNR & private civic groups have joined together to try to save the oysters. As far as benefiting the ecosystem, they're where they belong, they fit into the ecosystem & keep it running smoothly. Invasive species on the other hand have become a real problem, they don't fit in, they simply don't belong here. Walking catfish, snot rock & snake heads have become a big problem. Snake heads will attack & eat anything, & there's nothing in the bay to stop it, it has no enemies. Aside from being a part of the eco puzzle, a food source, $ maker, water cleaner it is also a tourist spot. By law the oysters can only be dredged by the old way, that means by sail. So tourist pay money to go out & dredge on these big old oyster boats
Oysters benefit the Chesapeake Bay and it's ecosystem as they are filter feeders that consume phytoplankton (free-swimming algae) and improve water quality while they filter their food from the water. They form reefs that provide structured habitat for many fish species and crabs. Go to http://chesapeakebay.noaa.gov/oysters/oyster-reefs for details.