Aquatic ecology and Biodiversity

Unit 11- Intertidal zone

11.4. Intertidal Muddyshore

Muddy shore habitats are areas of mud and sandy mud exposed between the extreme-high-tide and extreme low-tide marks.
Formation
Mud flats form from the deposition of mud in sheltered tidal water, particularly in estuaries where there is a large sediment supply.
Physical characteristics
•Substrate: particles range from fine sand to silt, and are often compacted into clay. drainage is poor, and anaerobic conditions exist just below the sediment surface.
•Wave action: the surface sediment is mobile in moderate waves due to exposure to wave action related to wind and to a tidal and longshore currents.
•Tidal regime: tidal range determines the area of shore that is exposed to the air.
•Water–land interaction: water conditions include summer and winter temperature extremes, formation and movement of ice, turbidity and salinity.
• Climatic conditions: air conditions include summer and winter temperature extremes, humidity, precipitation and wind.
Special features
Vast numbers of a few species of infauna depend on a diet of organic detritus. Examples Corophium sp with a population density of 15 000/m² and Macoma balthica 3500/m². These animal populations support large groups of migrating shore birds during the late summer. Migratory fish also visit to feed on the benthic (e.g., Corophium) and epibenthic species (e.g., Neomysis, Mysis etc.).
Ecosystem properties
Primary production is limited to diatoms and other microscopic and filamentous algae and grass. Most energy enters the system from the plankton, or as organic detritus derived from the land or adjacent tidal marshes. The detritus and associated bacteria are consumed by large populations of bivalve molluscs, amphipods and polychaetes. These in turn eaten by carnivores, and particularly by migratory shore birds. The crustacean, Corophium volutator occurs in the Bay of Fundy intertidal mud flats and is an important food source for the migratory Semipalmated Sandpiper.