booklet 9 - estuarine environments

• What is a climatic climax?

  The dominant plant species at the end of a phase of plant succession that reaches a state of ecological equilibrium appropriate to the climate experienced there.
• What are pioneer species

  The first species to populate an area
• What is meant by halophytic

  salt tolerant
• Conditions for a salt marsh to form

  - tidal regime

  - gentle currents

  - water and wave type

  - climate

  - sediment rich water

  - human action
• What type of material accumulates to form a saltmarsh

  Fine grained sediment
• Flocculation


  fine sediment carried by slow moving river meets the sea water flowing into the river mouth. As the two flows meet fine particles clump together to form larger heavier particles that sink to the bed
• Formation of a salt marsh

  Develops in areas sheltered from wave attack - fine particles or mud can settle from transported material (from estuaries), forming a mudflat. Salt loving plants trap seaweed. Currents are further reduced, causing further deposition. More plants of differing species begin to colonise the area (this succession is called halosere). The marsh builds up until it is only flooded during spring tides. They must be protected from wave attack in order to survive.
• steps to a saltmarsh

  1 - submerged estuary shore

  2 - mudflat

  3 - low salt marsh

  4 - high saltmarsh

  5 - climax vegetation
• Limiting factors for plant development in low saltmarsh

  Some of the plants may not be able to tolerate the high saline and PH conditions so not much grows and colonises in this stage
• Pioneer species


  - sea lettuce

  - marine algae

  - grasswort

  - spartina
• Species diversity change in a salt marsh

  Saltmarshes are very diverse. As the marsh starts to develop the conditions are very harsh and saline so not a lot of species can grow only plants like sea lettuce. As the marsh further develops, more species are able to colonise such as sea aster and spartina and grasswort. When the salt marsh is in the high salt marsh stage scurvy grass and sea lavender grow, finally in the climax vegetation plants are non salt tolerant and include ash and birch
• Changes in acidity


  As you go further inland, the stages of the saltmarsh get more acidic and more, non salt tolerant plants develop. The marsh goes from very saline to acidic as it progresses.
• Changes in marsh height

  As the marsh progresses it gets taller and taller, it starts off being very close to the shoreline around 0- 0,5 meters and eventually works its way up to around 2.5 metres tall where the climax vegetation is
• Changes in organic matter

  Organic matter gets greater as the marsh develops and conditions become less and less saline. Organic matter grows the further way it is from the estuary shore.
• How can humans influence development of a saltmarsh

  Both dredging and navigation as well as boating, leisure fishing power boating and jet skiing sailing and wind surfing have been suggested as factors contributing to saltmarsh erosion in the UK and this can slow down or stop the development of these ecosystems
• Severn Estuary formation


  Mudflats are formed by deposition of fine silt and sediment, deposition arises due to where the salt water meets the fresh water and loses energy, next a saltmarsh forms - due to vegetation colonising the mudflats and is a high saline environment - this whole process takes many years
• Severn Estuary - ecosystem importance

  Lots of different types of ecosystems with in the severn. Mudflats provide shelter for ecosystems and nourishment for nesting birds

  invertebrate population provide food for birds and fish communities

  Many fresh water streams intersect the marsh areas and intertidal inhabitants are found there
• Severn Estuary - threats

  sea level rise and any changes related to salinity of estuarine environment would effect the biodiversity

  climate change is a huge issue and would cause extreme sea level rise which would submerge the plants and they'd die. There would be increased storm activity due to climate change which could wipe out the marsh causing in to collapse