The Chesapeake Bay (VA) National Estuarine Research Reserve features four components that are all within the York River basin--Goodwin Islands, Catlett Islands, Taskinas Creek and Sweet Hall Marsh. Like most of the reserves in the national system, Chesapeake Bay-VA is diverse. The source of its diversity is its range of salinity gradient. Salinity is an important determinate of what species can live in an area. Located on the freshwater Pamunkey River, northern wild rice grows easily in the Sweet Hall Marsh component of the reserve. However, salinity is too high for it to grow at the Catlett Island component. Conversely, plants like saltwort thrive at the salty Goodwin Island component that would die if transplanted to Sweet Hall Marsh.