Mud flats and salt marshes Flashcards
Mudflats are
low-lying areas of the shore that is submerged at high tide and are composed of silt and clay
Where the mudflats are often located?
in estuaries or on the landward side of a spit
How mudflat is formed?
In estuaries where the flow of fresh water out of the river is slow and the sea water flows into the river mouth with each high tide and out with each low tide, bringing large amounts of fine sediments and meets the river which is also carrying its own load of fine silts and clays.
As they meet the finer particles settle out of suspension by the process of flocculation, where individual clay particles aggregate together to form larger, heavier particles that can sink to the bed.
How is the vegetation succession that develops on mudflats is known?
Holosere
What are holophytes?
plants and animals that can live in a salty environment
How vegetation succession takes place over mudflats?
Low-lying vegetation (algrass) begins to grow on the mudflats
Holophytes (glasswort, sea-blite, and spartina begin to colonize the area
The pioneers gradually develop close vegetation over the mud allowing colonization by other plants such as sea aster, marsh grass, and sea lavender ( up to 15 cm high)
As mud level rise, complex creek systems develop that channel the tides. Rushes and reeds become established, and trees such as alder, ash and then oak can grow to complete succession
By action of which processes mudflats can be impacted?
changes in sea level, wave action, changes to tidal flows, changes in discharge levels in the river
Where do saltmarshes form?
They form in coastal areas that already have mud flats
How much of an area do East Anglian salt marshes cover?
13,000 hectares, 30% of the entire U.K. remaining area
Why salt marshes in East Anglia are important for coastal defence?
Salt marshes act as a dissipator to storm wave action and as a substantial weight to the seaward toe of the wall to give increased stability against water pushing against it.
How much of the sea wall in Essex relies on salting as a ‘first line’ defense against the tide?
300 km out of 440 km of sea walls
How much of remaining salt marshes is eroded each year?
2%
Why are salt marshes are easily polluted?
Because saltings act as a sponge soaking up the pollutants holding them in place and preventing wider potentially more harmful distributions
Why the salting in East Anglia named the most protein-rich and productive land in the UK?
square meter of mud can hold 1200 warms, below the ground and 15000 snails hydrobia graze on its surface, producing clay-like ‘soil’ which has a direct benefit to the toe of sea walls
Which strategies are used to stabilise the saltings?
Foreshore recharge, wave breaks, brushwood polders, and groynes, set back
