Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: THURSDAY, August 24, 1995 TAG: 9508240009
SECTION: CURRENT PAGE: NRV-1 EDITION: NEW RIVER VALLEY
SOURCE: MARY F. LAURENT SPECIAL TO THE ROANOKE TIMES
DATELINE: LENGTH: Long
There's a place in Blacksburg you can go to smell the ocean, listen to the rhythm of the tides and watch oysters nestle on sandy marshland while shrimp and other sea creatures scamper. But don't run for your swimsuit just yet. This beach is in a greenhouse behind the Virginia Tech horticulture gardens.
John R. Lauth, a research scientist with Virginia Tech's Department of Biology, has created a real-world estuary on a 4-by-2-foot workbench. Estuaries - formed at the mouth of a river where fresh and sea water meet - are essential for shellfish production.
Lauth's objective is to test the effect of various pesticides on the aquatic creatures that inhabit an unpolluted salt marsh on Wadmalaw Island, near Charleston, S.C. His work is funded by $30,000 in grants from the National Marine Fisheries Service.
The system is a mesocosm, Latin for "middle world." It is not as big as real life, not as small as a test tube or microscopic environment.
"I was reading aquarium magazines and realized that us scientists could be building aquarium systems that were just as good as the real world," said the 40-year-old mechanical engineer turned marine biologist. Lauth believed he could improve on the two chief methods of testing pesticides: in man-made ponds, which are expensive and can be contaminated by particles blown in by the wind and on the feathers of birds; and in laboratories where only one species is tested at a time.
Lauth's mesocosm consists of a series of interconnected aquariums. Fresh water is pumped in at one end of the system, salt water at the other. High tide is set by filling the tanks to a level that covers all marsh sediment with water. Ebb tide is simulated by drawing water from the salt-water end, the place where the ocean would be in reality.
To populate the aquarium, Lauth traveled to South Carolina, located a nonpolluted marsh on Wadmalaw and dug up plants, animals and sediment, which he transported to Blacksburg in large trash cans.
Next he introduced his captives to the simulated environment. Each aquarium was outfitted with mesh screens and trays elevated to the proper height for high, mid and low tidal zones. Mud snails, grass shrimp, oysters, mussels and fiddler crabs were placed where they would have been in a real estuary.
The only other natural phenomenon left to replicate was what environmental scientists call a "rainfall event." Rain washes pesticides from land into rivers and streams and finally into estuaries and the ocean. Without rain, many pesticides would break down in the soil and never become pollutants. Lauth mimicked the heavy rain by pumping fresh water into the mesocosm until salt concentrations matched those of the real site after a heavy rain.
Carrying out the next phase of his study - pesticide testing - means he will probably kill the very sea creatures that he is trying to save.
In the Wadmalaw study, the murder weapon is AZM, or azinphosmethyl, an insecticide used in agricultural production.
Lauth introduced AZM into the first aquarium tank after a re-created rainfall event and watched what happened.
"What we saw wouldn't have been predicted in single species testing," he said. "At first, there was an incredible depression at the microbial level - everything died. But after 24 hours, there was recovery." The system began to return to normal.
Now that Lauth has proven his simulation system works, other uses for it are coming to light.
He has received a grant from the Army Corps of Engineers to reconstruct a contaminated site in the north end of San Francisco Bay. "This part of the bay was a holding for the U.S. fleet during World War II; and at that time, the Navy wasn't too concerned about what they threw over the side in the form of spent gunpowder, chemicals, and other by-products of its naval operation," Lauth said.
Now the base is closing down and the corps needs data to make environmental cleanup plans. Officials are shipping Lauth dredged material from the bay to see if he can build a salt marsh that sustains aquatic life.
Lauth wants to re-create the Florida Bay, south of the Everglades, to study decontamination in a tropical environment. This will involve constructing a barrier reef and a coral reef.
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