Salt pans at Aberlady
The transition from tidal flat to low and high salt marsh, transition zone and land. These shore-parallel zones of halophyte vegetation are typical of temperate tidal shorelines. Salt marshes show a range of subtle landforms that reflect the accumulation and recycling of mud and sand.
Google Earth image of the salt marsh west of the car park at Aberlady with its creeks and salt pans
Salt marsh
Definition: a flat, muddy coastal wetland found on low-energy coasts, with a cover of salt-tolerant grasses that is inundated periodically by the tide
Salt marshes form when mudflats are raised to the level of the average high
tide. The accumulation of mud is most common in estuaries where the river brings
fine-grained sediment to slack water but where wave action cannot rework the
settled mud. Grasses tolerant of salt water then slowly take hold and spread,
stabilizing the land through the growth of root systems and trapping more
sediment.
The ebb and flood of daily tides creates process and vegetation zones:
- the tidal flat remains under water for long periods and so terrestrial vegetation cannot establish itself
- the low marsh is often submerged under salt water but emerges at low to mid tide. At Aberlady, these mudflats are colonised by glasswort or samphire, a pioneer plant tolerant of high salinity and waterlogged mud and sand
- the high marsh is inundated less regularly and for short periods. Here the salt marsh grasses need to tolerate even higher salt concentrations as sea water evaporates.
- the transition zones at the landward edge of the salt marsh is only reached by extremely high springs tides or during storm surges.
Salt marshes form a buffer zone between mudflats and terrestrial habitats. These soft shores provide some of the richest habitats for shallow marine organisms and attract large numbers of wading birds. The marshes dampen wave activity and so protect the shore from erosion.
