Tidal salt marshes are found along the low-energy coastlines of mid- to high-latitude regions of the major continents (except Antarctica), and lie at the ecotone between terrestrial, freshwater, and marine systems (Greenberg et al. (2006) BioSci. 56, 8). As the marsh develops, halophytes (such as marsh samphire and sea aster in Britain) pave the way for less hardy species, and the marsh becomes part of the coastland; see van Wijnen et al. (1997) J. Coastal Cons. 3, 1. See Santos et al. (2013) PLoS ONE 8, 11 e78989. DOI:10.1371/journal.pone.0078989 on salt marsh vegetation stress and recovery after the oil spill in Barataria Bay, Gulf of Mexico.