New "eco-friendly" docks aren't much better than traditional docks at protecting salt marshes.

A study casts light on an issue linked with coastal growth. More people mean more docks.

And docks harm marshes by casting shadows on marsh grass -- a bit like moving your plants away from the window.

Clark Alexander of the Skidaway Institute of Oceanography studied three new types of new docks designed to let more light shine through.

He says, they weren't much different than ordinary docks.

"I think, for our part of the country, it doesn't make sense to spend a lot more money to build an 'eco-friendly' dock if your goal is to protect the salt marsh by allowing additional light to come through your dock," Alexander says.

Alexander says, the new docks might provide more benefit closer to the equator because they use slatted planks to let the light shine through.

He says, the most marsh-sensitive docks are just higher and narrower.

Marshes are incubators for the coastal ecosystem and are protected by state law.

A committee has to approve any new docks.

Federal regulators already are using the study in their permitting process.

Tags: Skidaway Institute of Oceanography, Coastal, coastal Georgia, marshes, GPB News, Clark Alexander, Skidaway Institute, marsh, docks