Organisms Associated with Oyster Habitats

You will also find several kinds of fishes and crabs that concentrate around oysters. Some are simply feeding on associated organisms, some are there for protection themselves, while some are there to lay their eggs and use the oyster shells as a nursery for producing their own young. The diversity of plants and animals found on oyster bars illustrates the important habitat role that oysters play in the Bay system. (for further details, read "Organisms Associated with Oyster Bars" and "Predators of Oyster Spat and Adults").

Oyster Disease and Its Impact on Your Oyster

Oysters infected with the parasite that causes Dermo eventually become weakened and die -- this may not occur until the second or third year of growth. When the oyster dies, its tissue rots and the infective stages of the parasite are released into the water. Nearby oysters can ingest these spores through their filtering activity and become infected; this usually happens during late summer or early fall in our region. The mode of transmission for MSX is still not fully understood, though its virulence is controlled to some extent by lower salinities (usually below 15 parts per thousand).

While spat produced in hatcheries for the Oyster Gardening Program will be initially free of disease. These oysters can eventually contract Dermo or, in high salinity regions, MSX as well. However, even if there are large losses in the floats, the survivors may be valuable for planting as future brood stock; that is because these survivors potentially have a natural tolerance for disease, which could then be passed onto some of their progeny.

Ongoing research efforts are attempting to breed oysters that are resistant to disease; once these are available, the Oyster Gardening Program will make every effort to distribute seed from these oysters. To learn more about oyster diseases, visit these sites:

• Oyster Diseases & Parasites
• More about Dermo
• More about MSX