Hurricane Irene left behind more than soaked furniture and buzzing mosquitoes.
For Hans Paerl, such large storms also bring new information about the coastal waterways he has studied for decades: how they work, how they can change over time and maybe how to keep them healthy.
"It's an amazing event, and it leads to interesting science," says Paerl, who runs a lab at the UNC-Chapel Hill Institute for Marine Sciences in Morehead City. "We don't like hurricanes, but when they happen, we go into overdrive."
In his 33 years studying the Pamlico Sound and the rivers that feed it, Paerl has seen the waters slowly rise because of the melting of faraway ice caps - and he has seen the sound's composition altered by increasingly frequent large storms.
Much of this information comes from a tracking system he devised and maintains. "FerryMon" uses monitors stuck to the bottom of the ferries that carry tourists and locals to the Outer Banks and has become a national model for similar programs from Nantucket in Massachusetts to Puget Sound in Washington state.
Paerl's work on the algae blooms that can choke water ecosystems has earned him international accolades, including a lifetime achievement award he received this year from a national research group.
He is the rare scientist whose work regularly crosses accepted boundaries, said Carolyn Currin, a former doctoral student and government scientist. Paerl works on freshwater and saltwater, local issues and their international implications - as well as advocating for the policy changes needed to keep water clean.
"He has been instrumental in helping to improve the water quality in North Carolina," said Currin, a microbiologist with the National Oceanic and Atmospheric Administration.
Amsterdam to Morehead
Tan with wavy, gray-blond hair, Paerl has long been drawn to the coast. He used to surf and sail and still enjoys fishing.
His connection to the water goes back even further to his family roots in the Netherlands, where he was born. His great-grandfather was a ship's captain, and many other ancestors were fishermen.
A deadly flood in his low-lying country when Paerl was a child gave him an early appreciation for the power of water.
Paerl's family immigrated to the United States when he was 11. His father, a small-business owner, had served in the British army during World War II.
Disillusioned with his postwar prospects, he applied for residency in the United States. In 1958, the Paerls joined family in California, where his dad found work selling shoes after failing to find work in New York.
Hans Paerl is happy with the choice, which allowed him to grow up as a " '60s California kind of guy" in the San Francisco Bay area. It's an easygoing persona that Currin said can be deceiving.
"He likes to laugh and has this jovial, outgoing personality," Currin says, "But he's a very ambitious, hard-working scientist."
He went to college at the University of California at Davis, where his research focused on Lake Tahoe, and was working as a postdoctorate researcher in New Zealand in 1978 when he ran across an advertisement for a job in Morehead City.
The job had been advertised twice by the time he came to interview, he said. He jumped at the chance to explore a new coastline.
Studying water quality
Paerl's studies in North Carolina started in the rivers that feed into the Pamlico Sound and the Neuse River estuary, where these freshwater systems meet the Atlantic Ocean.
What he's looking for are largely harmful algae blooms; some are actually toxic, while others just exist in such large numbers that they soak up the oxygen needed to support fish and shellfish.
The Pamlico Sound is the second-largest such system in the country and is central to North Carolina's tourism and fishery industries. But it's a constantly changing system - even more so in recent years, Paerl says, since tropical storms and hurricanes have become more common.
Storms cause a rush of freshwater to come in through rivers and lakes, often carrying with it pesticide runoff, wastewater and other nutrient-rich substances that can cause algae blooms to flourish.
Usually, the sound exchanges water with the ocean slowly, with only the flow between the Outer Banks' narrow inlets creeping through. After a storm, though, the sound can be almost entirely freshwater.
"There are all of these cascading events that occur after these big storms," Paerl says. "Understanding what impact these storms have is an important part of understanding our future water quality."
Paerl's research also takes a wider view, focusing on the global impact of climate change. He's leading an international research group on the topic, and he says his experience on the North Carolina coast has far-reaching relevance.
"North Carolina is at the forefront of the impacts of climate change in the coastal zone," Paerl says. "It's a huge, shallow coastal zone that's being rapidly developed and seeing sea levels rise. We've got a lot of threats facing us."
Paerl says he's seen the sea rise firsthand. His wife, a Beaufort native, has long owned a waterfront store that only recently has started to see water reach the doorway during major storms.
It's a similar situation to coastal regions in India and China, Paerl says.
Data from a ferry
His international connections have also led to local innovations. He hit upon the idea of using the state's ferries to collect data on a trip to Finland, where researchers were starting to attach automated data collection devices to the bottom of ferries that crossed the Baltic.
He had long struggled to get good data on the sound - its vast size, remote location and unpredictable conditions all conspired against his efforts. But the ferries were already traveling the length of the sound, even in winds of up to 40 miles per hour.
"After I saw that, the lights went on as far as how to deal with Pamlico Sound," he said.
FerryMon works in partnership with state agencies that provide the boats and use the data to make water management decisions such as when to close down fisheries. A related program, ModMon, relies on researchers to perform regular assessments in the Neuse River estuary.
Using the existing ferries saves money, but the state has cut funding to the program in recent years. Paerl has kept monitors on some routes by patching together state and national grants.
He says the data are needed to help policymakers decide how to minimize the impact of large storms and climate change on water quality by restricting pollutants upstream, for instance.
The stakes are high, he says, including the billions of dollars invested in tourism, real estate and fisheries along the coast.
"There's lots of money going into the coastal zone that needs to be realistically protected," Paerl says.
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