Environmental Engineering Reference
In-Depth Information
CHAPTER 6
The Ecology of Coastal
Wetlands
Paula Daniela Pratolongo
Introduction
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.
Sea level controlled wetlands comprise a wide variety of environments
from tidal flats to freshwater swamps, fens or barren salt flats, in a
continuum of increasing elevation from a shoreline to the upland. In the case
of the intertidal zone, the primary abiotic control on wetland structure and
IADO-CONICET-UNS, Cno. La Carrindanga km 7,5 (8000) BahÃa Blanca-Argentina.
Email: paulapra@criba.edu.ar
