Salt marshes

Salt marshes (also spelled saltmarshes) occur where fine sediments accumulate along sheltered shorelines of marine bays, saline lakes, and alkali sinks. Those in intertidal settings are well studied for two reasons (1) salinity reduces plant diversity and inundation/exposure regimes structure composition, facilitating manipulative studies of vegetation-elevation patterns and (2) large expanses of monotypic vegetation are amenable to analysis of ecosystem functions (productivity, nutrient dynamics, food web support, and landscape connectivity). Salt marshes continue to advance science in these areas. Several functions of salt marsh ecosystems are considered services of high value to society, for example, primary productivity, denitrification, and biodiversity support. In urban and agricultural areas, especially bays with major ports, up to 100% of salt marsh area has been destroyed or converted to human uses (e.g., salt ponds, fish ponds, diked and desalted lands for agriculture). Pollution, canals, subsidence, and increasing rates of sea-level rise (with global warming) continue to threaten salt marsh quantity and quality. Restoration efforts are underway in part to manage the retreat anticipated with rising sea level and to replace lost wetlands. Several innovative experiments in salt marshes are advancing both restoration practice and science.