Physical Parameters

Saltmarsh habitats are influenced by a number of physical parameters including:

  • Frequency and extent of tidal inundation and evaporation
  • Hydrology (ground water)
  • Geomorphology (land form)
  • Climate (temperature and rainfall)
  • Vegetation structure and processes

Some key measures used to investigate some of these parameters include salinity, soil compaction, water temperature, turbidity, rainfall and tidal flows. The presence of vegetation structure also has an important impact on the ecological processes of saltmarsh habitats. For more information please refer to our sections on vegetation monitoring and water quality. 

 

 

 

Sedimentation and Compaction

Sediment compaction can have a significant impact on the health of a saltmarsh habitat. It can have an effect on the saltmarsh vegetation and its associated epifauna as well as impact on the ecological function of the habitat.

Increased compaction can inhibit root penetration, make if difficult for saltmarsh fauna to burrow (e.g. crabs and gastropods) and reduce the amount of oxygen in the sediment.

Sediment hardness can be increased by vehicle use and trampling. Vehicle tracks also have the potential to change the topography of the saltmarsh which will impact on the hydrology of the area. Vehicle damage can also cause pooling which provides habitat for mosquito larvae.

Salinity

The level and frequency of tidal inundation is a driver of saltmarsh habitat structure. Tidal inundation is linked to salinity levels and salinity is impacted by rainfall, temperature (evaporation) and drainage (the longer tidal water remains in an area the greater potential for water evaporation and hence increased salinity levels).

Salinity influences the distribution and abundance of plant species, vegetation cover and productivity as well as the abundance of epifauna including crabs and gastropods. Most saltmarsh species can tolerate a range of salinities but there are limits or extreme levels which can prevent many species being present.

Turbidity

Turbidity is the measure of the amount of suspended sediment present in the water column.

One of the key ecosystem services provided by saltmarsh is the retention of nutrients and sediments. This trapping of sediment and nutrients can have a positive impact on the quality of water entering the adjacent estuarine system. This sediment is often high in Carbon, hence saltmarsh has the potential to be a significant carbon sink.

Vegetation structure can have an impact on sediment retention as it slows receding water which causes sediment to drop out of suspension. The presence of vegetation, its structure, height and density can influence the amount of sediment trapped.