Study: Plants vital to coastal health

CAMBRIDGE, Mass., Jan. 30 (UPI) -- U.S. scientists have found aquatic river plants, which have been removed in the past to speed flow, play a major role in the health of ocean coastal waters.

Massachusetts Institute of Technology Professor Heidi Nepf and former MIT graduate student Brian White studied the physics of water flow around aquatic plants and demonstrated the importance of basic research to environmental engineering.

They said their findings can be used to guide restoration work in rivers, wetlands and coastal zones by helping ecologists determine the vegetation patch length and planting density necessary to damp storm surge, lower nutrient levels, or promote sediment accumulation -- and make the new patch stable against erosion.

"We now understand more precisely how water moves through and around aquatic canopies, and know that the vortices control the water renewal and momentum exchange," said Nepf. "Knowing the timescale over which water is renewed in a bed, and knowing the degree to which currents are reduced within the beds, help researchers determine how the size and shape of a canopy will impact stream restoration."

The research appeared in the Dec. 25 issue of the Journal of Fluid Mechanics.