THIS WEEK'S TOP STORIES
The flood: For scientists, a rare opportunity for study
By Jason Lesley
William Conner was greeted by a chorus of frogs when he went to see how much damage this weekend’s heavy rain did to ongoing experiments in Strawberry Swamp at Hobcaw Barony.
“The rain really brought out the frogs,” said Conner, assistant director of Clemson University’s Baruch Institute of Coastal Ecology and Forest Science. Water in the swamp was hip deep on Saturday, and batteries and a computer used to measure rising tree sap were ruined. Conner studies the effects of man and nature on natural environments, and the weekend’s heavy rain fed by Hurricane Joaquin and channelled into South Carolina by an abnormal low pressure system presents him and other scientists at Hobcaw with some once-in-a-lifetime opportunities.
Conner doesn’t expect the record-setting rain to have any lasting effect on the swamp. “It’s all fresh water,” he said. Conner and his students are still measuring salt washed into the swamp as ocean water during Hurricane Hugo 26 years ago. “We’re getting close to the end of the growing season,” he said. “Things are starting to shut down. As long as it flushes and gets back to normal in a week or so, it shouldn’t have much effect. We might see something; we might not.”
Conner said his associate Alex Chow’s monitoring of the Waccamaw River’s water quality is more likely to yield interesting data. Chow has been taking samples from the river between Murrells Inlet and Georgetown since the rain started on Friday. “With all that flooding,” Conner said, “some sewage treatment plants could wash out. We are looking at E coli. Don’t wade in the water. It’s not the safest thing to do. You don’t know what’s overflowed upstream.”
Dennis Allen, director of the University of South Carolina Marine Lab at Baruch, said he’ll be interested to see how North Inlet and other parts of the Hobcaw Barony ecosystem respond to the rain. “We’ve never seen such a big surge of freshwater into North Inlet in 35 years of record keeping,” he said. “When you get these kinds of events, you not only see big changes in salinity, all kinds of particulates get transported into the system. It will present some real interesting opportunities for us. The effects will last for weeks before the forest is finished bleeding. There’s a whole lot of water stored out there.”
Allen said areas like Murrells Inlet and Pawleys Island, those without a river supplying fresh water, are ruled by tidal exchanges. Saltwater will restore the chemical balance rather quickly. “Winyah Bay, Santee and Little River will probably feel this for weeks and months to come,” he said. “This comes after a prolonged period — we are talking years — of declining discharge. It could present quite a shock to the system in terms of resetting, displacing some animals that are very much more salt tolerant with ones that can cope with swings of salinity.”
Oysters, clams and shrimp will be most obviously affected by the influx of rain water, Allen said. The state Department of Health and Environmental Control will postpone the shellfish season for some time to assess food safety. “It’s probably a wise choice,” he said, “particularly around more urbanized estuaries. There’s no doubt septic systems have flooded over, and other bacterial contaminants from streets are in the water. Oysters and clams are very good at filtering those size particles out of water, making a potential problem for anyone who might eat them.”
Allen said the oyster beds will be open once salinity levels return to normal, killing the bacteria. “None of this is a problem for oysters and clams,” he said, “but it is for us.” This was shaping up as a banner year for oysters because of the extraordinary high tides recently. “King tides kept oyster reefs submerged where they can feed constantly,” Allen said. “They should be nice and fat and pretty desirable to those who like to eat them once they purge themselves of bacteria.”
Shrimp, on the other hand, will not be easy to get with a cast net this year. “By all accounts,” Allen said, “we had a really good start to inshore shrimp baiting. I’d be surprised that the vast majority haven’t been displaced into the ocean. The water is just fresh; the currents too strong. It’s good news for commercial trawlers in the coming weeks, perhaps not for those looking for them inside the estuary.”
Eric Smith, research coordinator for the USC Marine Lab at Baruch, said the tea-colored drainage from forests into North Inlet is unprecedented in terms of magnitude and duration. “It will be interesting,” he said, “to see how long it takes for that pulse to work itself out of the system.” He said the water will get an unusual amount of carbon and organic matter from the land. In summer those nutrients could cause a steep decline in oxygen and kill fish. Smith doesn’t expect that to happen with water temperatures cooling down. “We’ll be looking for the overall impacts of all that fresh water on water chemistry,” he said. “It’s still early. We definitely rallied and got additional sample collectors and instrumentation out there to take a look at this. We are interested to see what the chemical and biological effects will be. We don’t think they will be anything detrimental. The natural environment can take these things in stride much better than the built environment.”