LEFT: jim Swartzenberg, a shellfish farmer, says his occupation helps the environment: "If we had more oyster farms, we'd have cleaner water. 

 RIGHT: Swartzenberg and his wife, Bonnie, grow and harvest oysters on 100 acres of bottom leases. 



citing data from the N.C. Division of Marine 

 Fisheries (DMF). 



Many of these counties have experienced 

 phenomenal growth. During the past 1 5 years, 

 Brunswick County's population has grown 

 by nearly 60 percent, and New Hanover's has 

 grown more than 40 percent, according to the 

 U.S. Census Bureau. 



"The coastal development pressure is 

 just enormous," says Cahoon, who is also a 

 Wilmington resident. "There is hammering, 

 sawing and bulldozing going on constantly." 



As these areas fill up with transplants 

 and retirees, nearby coastal counties — some 

 with traditionally more rural land — appear 

 to be absorbing the overflow. Since 1990, 

 Pender County's population is up more than 

 50 percent, and Carteret County's is up more 

 than 1 7 percent. 



In Onslow County, population growth 

 didn't even reach a half percent from 1990 

 to 2000. But from 2000 to 2004, the county's 

 population jumped more than 2.5 percent. 



Interested in nonpoint sources of coastal 

 pollution, Mallin looked at population trends 

 and shellfish bed closures in Carteret, Onslow, 

 Pender. New Hanover and Brunswick 

 counties from 1984 to 1997. His analysis 

 demonstrated a strong correlation between 

 increases in human population and increases 

 in shellfish bed closures due to high fecal 

 coliform bacterial counts. 



Animal droppings, livestock manure and 



human sewage are all sources of fecal coliform 

 bacteria that can be picked up by runoff. The 

 amount of fecal coliform bacteria in water is a 

 critical factor in determining whether it is safe 

 to harvest shellfish. 



The study showed that human population 

 increases alone could explain approximately 

 70 percent of the variability in annual shellfish 

 area closures caused by fecal coliform 

 bacteria. Mallin reports. 



Mallin took his results one step further 

 and examined pollution levels in five estuarine 

 watersheds in the Wilmington area. Each 

 had various configurations of population 

 density, type of land use and development, and 

 intensity of development. His analysis showed 

 a strong correlation between the number of 

 people living in a watershed and the fecal 

 coliform bacteria counts in the closed area. 



But the strongest correlation Mallin 

 found was between fecal coliform bacteria 

 counts and percent coverage of impervious 

 surfaces, or developed land. 



"For all these watersheds considered 

 collectively, percentage watershed-impervious 

 surface coverage alone explained 95 percent 

 of the variability in average estuarine fecal 

 coliform bacterial concentration," Mallin 

 reports. 



But shellfish farmers, like the 

 Swartzenbergs, don't need scientific studies 

 to confirm what they already know. After 

 heavy rains, they must temporarily close their 



shellfish beds because of the polluted runoff. 



After about 1 .5 inches of rainfall or 

 more, most of the "conditionally approved" 

 shellfish harvest areas are closed, confirms 

 Fowler. Before the areas can be reopened, 

 shellfish sanitation officials must take 

 samples to determine if the levels of fecal 

 coliform bacteria are safe. In order to reopen, 

 water sample results must have a fecal 

 coliform bacteria count of no more than 

 14 MPN (most probable number) per 100 

 milliliters. 



"Shellfish — oysters, clams and 

 mussels — concentrate bacteria in their 

 stomachs and intestines," says Fowler, 

 explaining why the fecal coliform bacteria 

 count needs to be low. 



"When eating shellfish, we eat the entire 

 organism, including the guts and intestines 

 — it's not like eating shrimp, where you are 

 consuming just muscle." 



REGULATIONS TO 

 PRESERVE RESOURCES 



How can the demand for development 

 and the need for healthy shellfish beds be 

 reconciled? 



"Planning ahead," says Mallin, "so you 

 minimize the amount of impervious surfaces 

 and maximize green space." 



The two major "planning ahead" 

 strategies for nonpoint source pollution in 

 coastal North Carolina are the Coastal Area 



8 Coastwatch I Winter 2006 I www.ncseagrant.org 



