THE DEVELOPMENT OF TIDAL CREEK SURFACE FILM IN TWO MARSHES AT DIFFERENT STAGES OF RESTORATION AND IN A NATURAL MARSH


urface films on marsh creeks form water/air interfaces of high biological activity. In order to assess the impact of marsh restoration practices on the surface film component of the marsh ecosystem, we are studying the surface film and underlying water in creeks of three marsh types in Delaware: a natural Spartina alterniflora marsh, a Phragmites australis marsh restored to S. alterniflora, and a Phragmites marsh in the process of restoration (sprayed with a glyphosate herbicide and burned to remove the dead canes just prior to the initiation of our study). We have found that particulate matter at high tide, measured as dry weight and ash-free dry weight, is often orders of magnitude greater in the surface film than in the underlying water. The metabolic activity of the films and underlying water, determined by measuring photosynthesis and respiration in the field., is significantly higher in the surface film than in equivalent quantities of underlying water, indicating the biological richness of the film. There is less biological activity in the film of the burned Phragmites marsh than in that of the restored or natural marshes. In July, thousands of algal cells per microliter were observed in the surface film while few to none were counted in the water column.

Funding Source: Academy of Natural Sciences of Philadelphia, Marsh Ecology Research Program

Phragmites marsh killed using herbicide and burning

Phragmites
marshes are killed with herbicide and burned in an effort to return these areas to the natural Spartina marshes they once were.

Surface film

Surface film on a marsh creek.


Collecting film throughout a tidal cycle
The film is collected throughout a tidal cycle and then analyzed. Comparisons are made with the underlying water column water.

Fiddler crab burrows
The number of fiddler crab burrows in the bare areas of the burned marsh is more than ten times that in the vegetated areas of the burned site or in the vegetated recovered site.






Dr. Denise Seliskar


Halophyte Biotechnology Center


Dr. John Gallagher

Revised: May 17, 2010