Do Boat Docks (with holes in them) Harm Marsh Grasses?

In kindergarten I learned that light cannot pass through solid objects. Wooden blocks left shadows so, I figure, would a wooden dock prevent sunlight from reaching marsh grasses when built over the marsh, seems like a pretty simple concept. Does this hold true for docks with holes? After three years of study (most people in kindergarten only get one year to study) a researcher for the Skidaway Institute of Oceanography concluded that it does. During most of the year docks with open grating still block almost as much sunlight as those built of solid wood, hence impacting marsh grasses growing beneath the dock. What took them three years to figure out seems like a no brainer to me but here is the catch. Even though docks with open grating block out almost as much sunlight as wooden docks without the holes some folks in Georgia, living near the state’s 590 square miles of tidal salt marsh are using this study to push for larger docks. Georgia’s salt water marsh makes up a third of the total marsh on the entire east coast and is a habitat and critical part of the food chain for fish, shrimp, and crabs. Along with a system of barrier islands the marsh also provides an important buffer for weather related storm surge. Georgia private waterfront homeowners have built 2,300 single-family docks from 1996 to 2011 and the answer to the question is yes, docks with or without holes negatively impact marsh grass growth in Georgia’s coastal saltwater marshes.