Dauphin Island, Alabama...storms, plants and animals shaping the coast

A good example of climatic and ecological influences on geomorphic processes comes from the coastal barrier islands of the Gulf Coast of USA, where I recently attended a conference.  Dauphin Island, Alabama, for example, was badly affected by Hurricane Katrina, which cut off the west side of the island completely. The image from Google Earth below shows what the island looks like today. If you scroll to the west you will, eventually, find the western tip of the island which is now separated from the rest by some distance.


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The USGS have carried out extensive surveys of Dauphin Island before and after Hurricane events - check out this website for some really good images and explanations of the impact of Hurricane Katrina:
http://coastal.er.usgs.gov/hurricanes/katrina/lidar/dauphin-island.html

As a result of day to day coastal processes the island is constantly changing, and hurricanes regularly 'reset' the sediment stores.  However, organisms also play a big role here - both erosive and protective. The local authorities are currently using plants to aid sedimentation on the backshore dunes - as shown in the image below. They discourage walking over the dunes, as this damages the vegetation and releases sand.

'These dunes aren't made for walking' 

Further down the beach, there is widespread evidence of organisms (probably crabs) causing widespread mobilisation of sediment through extensive burrowing activity.

The results of an energetic burrowing crab

The question for geomorphologists is how to quantify in a meaningful way the different contributions of plants and animals to moving and storing sediment here, and to compare them waves and winds (all low magnitude and high frequency processes) and also with the high magnitude-low frequency impacts of storms and hurricanes. How would you do that?

Thanks to Dr Carole Sawyer, University of South Alabama for introducing me to Dauphin Island.