Water physically interacts with plants in the coastal zone, often in the form of erosion.  Recent results from work on a NOAA-funded grant challenges the traditional paradigm that plant roots directly prevent erosion in salt marshes.  Using side-by-side experimental units in a wave tank, we have shown that the presence of plants or live plant roots makes no significant difference upon the amount of erosion.  Differences in plant species morphology do not alter the erosion rates either.  Rather, the soil type is the master variable that determines the erosion rate.  Interestingly, the input of plant detritus in the form of finely-grained organic particles lends cohesiveness to the soil matrix, and so plants indirectly reduce erosion. 

I have been conducting similar work on the effect of Sargassum algal wrack upon beach erosion.  In this NOAA-funded grant, results show that Sargassum enhances dune plant growth, reduces wave erosion, and builds beach elevation.  We have also been working at a site where too much sediment has entered into a small bayou, radically altering elevations and changing the ecology of the system.