Seagrasses, as plants, need light for photosynthesis and production. This study measured the changes in productivity and light in a back-barrier estuary and connected those changes with the type of seabed within the estuary. We found that the locations with seagrass on the seabed had more light getting through the water and higher productivity because of the way seagrass keeps sediment on the seabed during wave events. When sediment stays on the bed, it cannot reduce the light in the water.