THE VIRGINIAN-PILOT
Copyright (c) 1994, Landmark Communications, Inc.
DATE: WEDNESDAY, June 15, 1994 TAG: 9406150503
SECTION: LOCAL PAGE: B1 EDITION: NORTH CAROLINA
SOURCE: BY LANE DeGREGORY, STAFF WRITER
DATELINE: 940615 LENGTH: PEA ISLAND
But no one really knows what effect the federal beach nourishment project is having on the environment.
{REST} Tourists can see that the beach is wider in some places along the six-mile stretch of sand. Wildlife officials know that sea turtles have changed their nesting habits in that area. But no one has looked at the mole crabs, worms and coquina clams that live along the swash line - and have been buried beneath the more than 2 million cubic yards of sand.
Until now.
This week, six University of Virginia students and two U.S. Fish and Wildlife Service employees began surveying sample sections of the barrier island beach swash line, that strip of sand where waves roll over and back. By analyzing sand grain size, wave velocity and organisms that live along the surf line, they hope to determine how beach nourishment projects can work in harmony with the environment.
``We're not trying to figure out if the Corps is doing something wrong by pumping sand on the beach,'' said Dolan, who added that beach nourishment is the only thing holding Pea Island in place.
``All we're trying to do is provide information about how and where moving sand can be placed in the best possible manner,'' he said. ``Clearly, the characteristics of the beach are changing. Whether that's a long-term, irreversible process is yet to be seen.
``The data we're collecting will help determine the ecological impacts of beach nourishment. It's as important as any data that's been collected out here in 25 years.''
North Carolina's barrier islands have been migrating since their inception. Federal, state and local officials have spent years trying to figure out ways to control erosion and stabilize the sand. In 1989, the Corps of Engineers agreed to place sand dredged from Oregon Inlet and off-shore sandbars directly onto the federally managed Pea Island National Wildlife Refuge.
Once a year for the past five years, dredge boats have pumped billions of grains through long pipes onto the beach. This year alone, 350,000 cubic yards of sand will be sent from the inlet onto the shore. Each time the sand is pumped onto the beach, it ``immediately wipes out the swash organisms for the rest of the season,'' said graduate student Cinde Donoghue, who is coordinating the project for her Ph.D. dissertation.
``Swash organisms - coquina clams, beach worms and mole crabs - indicate the ecological health of the entire beach,'' Donoghue said while sifting sand Tuesday afternoon. ``They are the bottom of the food chain. Shore birds, migrating tropical song birds, fish and other animals rely on them as a primary food source. When those wash organisms are affected by beach nourishment, the whole ecosystem is affected, too.''
Every day for the next five days, Donoghue and the other students will collect sand samples from two separate areas of Pea Island beach at five specified time periods. One area, just south of the old Oregon Inlet Coast Guard Station, has been nourished with dredged sand. The control area, about 4 miles south, has not yet received any off-shore sand.
Using plastic boring tubes and hand-held sifters, the students are recording grain size of the sand and counting critters which come up in their sample. By working continuously throughout the tide cycle - and recording other data such as wave size and velocity - they hope to provide a comprehensive picture of how the swash organisms live and move throughout the tidal cycles. They also will have a better idea of how dredged sand affects the organisms' habitat.
``All of those swash organisms are burrowers. So if you change the grain size of the sand by pumping coarser sand from the channel or finer sand from under the bridge onto the beach, you change the penetrability of the sand,'' Donoghue said. ``The dredged sand is much harder to dig than the natural beach sand.''
Although Dolan and Donoghue said it's too early to tell what impact the nourishment project is having on the beach environment, some preliminary results already are apparent.
Sea turtles, for example, can't climb the steep piles of sand that the Corps dumps along some areas. They have to lumber along the beach to find more gradual slopes on which to build their nests. Even then, if they nest in areas where the off-shore sand has higher mineral contents than the regular beach sand, the eggs often are ``cooked to death in the sun or come up sterile,'' Donoghue said.
The students, who are conducting the research project for free, said they don't intend to undermine beach nourishment. On the contrary, they hope to help federal officials decide which types of sand should be placed where - and how the sand should be sculpted on the beach.
They plan to return to the Outer Banks in August to collect a second set of samples.
``It looks like there's going to be dredging here forever,'' Dolan said. ``We might as well be able to tell managers of the wildlife refuge that sand from under the bridge should be spilled somewhere different from sand on off-shore bars.
``And it would help if we could tell them how to pile the sand at slopes which would be more natural to the beach and its organisms.''
by CNB