ABSTRACT
Coastal wetlands have always changed in time and space, with climate and sea level driving their long term evolution. The last ice age, which occurred from approximately 110,000 to 10,000 years before present, buried much of the current temperate coasts and continental shelves under thick layers of ice. During the maximum extent of glaciations, about 20,000 years ago, the mean sea level decreased to about 120 m below the present as a consequence of the massive storage of water on the continents. At that time, coastal wetlands would only have existed along those coasts that were free of permanent ice. Even at warmer latitudes, wetlands would not have occupied the present shorelines, but a fringe on the upper continental slope (Wolanski et al. 2009). After the last glacial maximum, the mean sea level rose rapidly, reaching its present world averaged (eustatic) level about 6,000 years ago. Coastal environments responded to these changing conditions and the land elevation related to sea level determined, at any time, the presence and location of wetlands.
