Long-term efforts to restore oyster reefs in the Chesapeake Bay have shown positive ecological effects, according to a study by researchers from the University of Maryland, Baltimore County (UMBC), the Smithsonian Environmental Research Center, and the National Oceanic and Atmospheric Administration (NOAA). The study, published in the journal Ecosphere, focused on Harris Creek, which is one of the largest oyster restoration projects in the world, covering about 1.4 square kilometers. Scientists used underwater video and high-resolution sonar imaging to evaluate the health of the restored reefs and the marine life living there, specifically nekton—free-swimming animals such as fish and turtles—6 to 10 years after the restoration was completed. The results showed that the method used for restoration had a significant impact on the reef's ecological value. Reefs built with a stone base and juvenile oysters attached to adult shells (spat-on-shell) had the best habitat scores. These reefs showed more vertical structure and complexity compared to those restored with spat-on-shell alone or those that had been regularly harvested. While restored reefs had fewer total fish, the fish that were present tended to be larger. The highest number of fish over 30 centimeters (about 12 inches) in length was found on reefs that included stone substrates. The study suggests that the three-dimensional structure of the restored reefs provides shelter and feeding opportunities for larger, more valuable fish species. Sonar data showed that animals in these restored areas are using the habitat differently, with more species living and feeding near the bottom, unlike in harvested or unrestored areas, which were dominated by small, schooling fish. This shift highlights the potential of restored reefs to support a more diverse and ecologically beneficial community of marine life. The timing of the study was important in understanding the long-term success of restoration efforts. By surveying the reefs at least seven years after restoration, scientists could determine whether the benefits were sustainable over time. The study found that the restored reefs maintained high oyster coverage and complex structures for years after construction. This aligns with broader efforts to revive the Chesapeake Bay’s oyster population, which is now only about 3% of what it was historically due to overfishing, disease, and environmental changes. The study's use of underwater video and sonar technology offers a new way to monitor submerged reefs in murky estuaries, where traditional sampling methods can be less effective. This approach could be valuable as oyster restoration projects grow around the world, helping managers assess the quality of habitats and the ecosystem services they provide more efficiently and at a lower cost.