Mesocosm (Marsh Organ) experiment at Blackwater National Wildlife Refuge, MD, 2012

This experiment examines the effects of tidal inundation on the growth of salt marsh vegetation. We measured the response of plants to disturbance across a gradient in inundation times by transplanting tussocks of Schoenoplectus americanus into mesocosms of different elevation. The mesocosms were arranged into structures commonly described as �marsh organs�. Here we utilize two marsh organs each containing 54 mesocosms constructed of 6-inch diameter (0.0182, m2) polyvinyl chloride pipe, arranged into nine rows containing six pipes of identical elevation. We conducted the experiment in a large brackish marsh on the Atlantic Coast of North America. The study site is adjacent to the Blackwater River, a tributary of the Chesapeake Bay (Maryland, USA) (Blackwater, 38.40�N, 76.07�W). Changes in water level are primarily driven by meteorological events, with mean astronomical tides of <0.25 m. Long-term porewater salinities average 10 p.p.t. within the marsh soil, and intertidal vegetation is dominated by Schoenoplectus americanus and Spartina patens.