LIVING FILTERS 



The initiative to counteract the 

 contamination in the bay began with millions 

 of innovative solutions — oysters. 



Oysters possess amazing filtering capaci- 

 ties, as one adult oyster can filter approximately 



the bay. There also was a high incidence of 

 petroleum byproducts — carcinogens that pose 

 dangers from long-term exposure. 



Thousands of ribbed mussels and clams 

 were placed among the oysters because each of 

 these shellfish targets a different food source. 



10 gallons of water over 24 hours, according to 

 Donovan-Potts. And because the bay contains 

 101 usable acres of water, the amount of oysters 

 needed to filter the entire bay would have to be 

 substantial. 



In this case, three million oysters were 

 placed within the bay over a four-year period. 

 That adds up to at least 30 million gallons of 

 water being filtered each day. 



The main concern was to filter the imme- 

 diate danger of E. coli and other bacteria from 



Oysters feed on heavy organics and con- 

 taminants. Ribbed mussels eat phytoplankton. 

 Clams feed on bacteria. 



Because "oysters have the greater filtering 

 capabilities," they were used the most, accord- 

 ing to Donovan-Potts. 



Valued for research purposes only, the 

 oysters cannot be eaten and may be contami- 

 nated with the same pollutants they filter. 



Juvenile oysters, known as spat, were 

 placed throughout the water column of the bay 



in mesh bags. Spat start at 20 mm and can grow 

 to 120 mm. And, the tiny oysters are cheap 

 — just $18 per thousand. 



Reviving the bay also required boosting 

 oxygen levels. Five aerating devices were 

 placed in the bay to pull oxygenated water from 

 the surface and force it towards the oxygen- 

 depleted bay bottom. The hope is to pull flow 

 in from the New River and restore the natural 

 hydrology of the bay. 



Once the aerators no longer are needed 

 in Wilson Bay, they will be moved to other 

 restoration projects. 



Meanwhile, five hydrolabs in Wilson Bay 

 monitor water quality every 15 minutes. 



The oysters are monitored from 15 study 

 areas where samples are collected, analyzed 

 and replaced by Jacksonville staff, students and 

 volunteers. 



The project was well documented and 

 can be duplicated in any municipality, says 

 Donovan-Potts. 



The New River, which feeds Wilson Bay, 

 was deemed one of the worst rivers in the 

 state by the N. C. Division of Water Quality 

 in 1991. The bay alone was described as 

 "ecologically dead" and "nutrient sensitive. " 



LIFE RETURNS 



Expectations at the beginning were 

 modest. 'The elected officials thought this 

 was a wonderful way to clean up the bay. The 

 scientists told us that this would jump-start the 

 process," says Hargett. "Both scientists and 

 elected officials were pleasantly surprised that 

 there were some successes as soon as there 

 were." 



Successes included return of migrating 

 birds, marsh crabs, blue crabs and various spe- 

 cies of fish. 



"The flounder have come back. We've 

 been catching croaker, spot, mullet, menhaden," 

 says Tami Dubois, water quality technician for 

 the City of Jacksonville. 



Since the closing of the wastewater 

 treatment plant, implementation of the bivalve 

 planting, and initiation of stormwater manage- 

 ment measures, the bay's water quality has 



Continued 



COASTWATCH 9 



