Are Artificial Barriers Aiding Proliferation Of Invasive Aquatic Vegetation?

When salinity is low, milfoil fragments from these freshwater refuges end up in nearby estuarine grassbeds, where they subsequently outgrow and competitively displace native submerged grasses.

To test these hypotheses, Dr. John Valentine and Marine Technician Susan Sklenar, both of the Dauphin Island Sea Lab (DISL) in Alabama, are currently comparing the results of salinity tolerance experiments they have conducted using milfoil at the DISL with two years of field data which document salinity patterns within the upper reaches of Mobile Bay.

The preliminary results of these experiments suggest that only the most extreme salinities, those observed during hurricane landfalls in the northern Gulf of Mexico, are lethal to milfoil.

"Right after Hurricane Katrina, we noticed that milfoil was not as abundant in those places where it used to be plentiful," recounts Dr. Valentine. "Whether it was the turbidity from the storm or the salinity from waters crashing over the MBC, we're hoping these experiments will be able to help determine the cause."

In the coming year, Dr. Valentine and his colleagues will be conducting additional field experiments to determine if in fact milfoil will outcompete native grasses for habitat within this estuary. It is hoped that these experiments, when completed, will allow DISL to make data-based recommendations for habitat restoration later next year.