The eastern oyster, <i>Crassostrea virginica<i>, is a gregarious, reef-forming organism. Oyster populations that once dominated the Chesapeake estuary have declined significantly and interest has recently arisen to restore the economic and ecological benefits of native oyster populations. Understanding the ecological importance of oysters and oyster reefs is critical to the restoration of the estuary's ecosystem as a whole. Oyster densities on most Maryland reefs are very low, however, natural reefs formed in other areas are comprised of high densities of oysters. In order to maximize the effectiveness of oyster restoration, it is important to determine how oyster density may affect oyster growth, parasite prevalence and the formation of reef habitat utilized by the benthic community.

In the fall of 1999, twelve 0.2-acre experimental plots were constructed in the Patuxent River, a tributary of the Chesapeake Bay, by placing fossil oyster shell on a barren natural oyster bar. The plots were assigned one of four treatments, zero, 124, 247, 494 oysters/m^2, in a completely randomized design. Oyster growth was 0.117 (± 0.0037 SEM) mm/day for the 2000 season and slowed to 0.067 (± 0.0061) mm/day in 2001. Throughout the study, oyster growth was independent of the density of oysters observed. Colonization of the oyster reefs with fouling organisms was correlated to the density of oysters.