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University Gazette

The University of North Carolina at Chapel Hill

Paerl turns a world of clues, a penchant for practicality into a national standard for water monitoring systems

Hans Paerl has helped ecosystems around the world. But he’s having to work extra hard to protect the Pamlico Sound.

Hans Paerl, left, works with technician Karen Rossignol to collect water samples through the FerryMon system, which has become the model for monitoring systems across the country.

In 2006, after Tropical Storm Ernesto plowed through eastern North Carolina, fishermen reported massive fish kills in the Neuse Estuary. Typically, when millions of fish turn up dead, it’s not an easy mystery to solve. But Hans Paerl and colleagues were prepared for their investigation long before Ernesto had even formed in the Atlantic.

Paerl, a William R. Kenan Professor of Marine Sciences, had installed special equipment on three ferries to monitor water quality in the Pamlico System, including the Neuse Estuary. The instruments could alert Paerl when something fishy was happening to water composition.

After Ernesto, Paerl discovered high levels of chlorophyll in the sound. More chlorophyll meant more algae. And Paerl knew that too much algae could wreak havoc in sensitive ecosystems.

Sure enough, Pearl and colleagues found Karlodinium veneficum, an algae species that produces a deadly chemical called karlotoxin. If there’s enough karlotoxin in the water, fish would die en masse.

Murder solved. It was Ernesto with the karlotoxin in the Neuse.

But how exactly did Ernesto produce so much toxic algae and – fast forward five years – what happened after Hurricane Irene tore through the Pamlico Sound last summer?

That’s where the plot thickens. Paerl has some of the answers, but Irene, so far, has gotten off scot-free.

A life aquatic

Paerl’s quest to keep our water healthy began when he was a child in Amsterdam, where he heard tales of the ocean from his seafaring relatives.

When his parents emigrated to the United States, Paerl took to surfing along the northern California coast and exploring Big Sur. At UC Davis, as a work-study student, he was assigned to cut vegetables from surrounding fields. But he hated that so much that he finagled his way into another job – working on Lake Tahoe with renowned professor Charles Goldman.

Paerl was back at home on the water and stuck with Goldman as a graduate student and post doc.

“One project involved microscopic algae,” Paerl recalled. “A couple of professors let me use their electron microscopes to see the detail of the algae’s structure. It was really amazing, the complexity that allows algae to move throughout the water column to seek ideal growing conditions. It was like watching a whole other world.”

After UC Davis, Paerl took a job in New Zealand, where some scientists suspected that human activity was the main driver of massive algae blooms.

Algae love nitrogen and phosphorus, and those two nutrients are necessary parts of any ecosystem. But they’re also major components of chemical fertilizers that farmers use. They’re in animal waste, decaying plants, rainwater and the atmosphere. Paved surfaces help speed up nutrient movement into the water.

While in New Zealand, Paerl showed that agricultural fertilizers were percolating through porous volcanic soils on the North Island, causing nitrogen and phosphorous to seep into rivers and streams that fed the lakes. Algae blooms were the result.

Paerl figured out that farmers were using too much fertilizer and helped researchers figure out adequate amounts for farming without harming waterways.

After three years of feeling isolated from friends, family and colleagues, he applied for a position at UNC. Before the interview in Chapel Hill was over, he was offered the job.

That was 1978. Since then, Paerl has investigated algae blooms across the globe, from the Baltic Sea and the open ocean all the way to Antarctica.

In China, Paerl has helped scientists manage an ecological disaster on Taihu, a huge lake in eastern China as green as pea soup most of the year due to massive algae blooms. It’s a shallow, calm lake that’s easy to survey.

Not like the Pamlico Sound, which is so large that state agencies and researchers can’t afford to monitor the entire system consistently; taking a boat out once in a while to sample the water isn’t very informative.

As a result, Paerl said, the Pamlico was the largest body of water in the United States about which we knew the least.

He figured out a solution for that during a trip to Europe in the 1990s.

Ferries to the rescue

Scientists in Finland equipped a ferry with special instruments to conduct water analysis automatically every day on the Baltic Sea.

“On the Pamlico Sound, ferries are the first thing on and the last thing off the water every day,” Paerl said. He knew he could create an unparalleled data set of water samples, one the state could use to determine how well it was managing the sound’s water quality.

Paerl and his colleague Joe Ramus at the Duke Marine Lab wrote a white paper for the N.C. Sea Grant program in 1997, but no one paid much attention to it until hurricanes Dennis, Floyd and Irene swept through North Carolina waters in 1999 (yes, there was a Hurricane Irene that year).

“We all woke up to satellite images of the flooding down east and a muddy Pamlico Sound on the front page of The News & Observer,” Paerl said. “Then people started calling me.”

In the aid package after Floyd, the N.C. General Assembly included funds for Paerl’s project, which he called FerryMon – short for Ferry Monitoring System.

From early 2000 through June 2011, three ferries that carried passengers across the Pamlico Sound also carried water sampling instruments below deck. Paerl provided public access to his findings and helped the state manage the water quality of this large system.

Over the past decade FerryMon has become the model for monitoring systems across the nation, including on the Delaware Bay, Long Island Sound, Puget Sound and Nantucket Sound.

When Ernesto pounded the Neuse River Estuary, Paerl showed how fragile the ecosystem is and how rapidly it can change due to nutrient overloading.

Fish and other sea life are sensitive creatures. A little too much nitrogen – no matter where it comes from – can cause algae to bloom and cause major damage to the Neuse.

But last June, the General Assembly did not include FerryMon in the state budget for the first time in 10 years. So Paerl can’t pay graduate students and technicians to replace sensors or calibrate the instruments. There’s no money to pay technicians to analyze the samples or manage the mountains of data the ferries collect.

“The timing couldn’t have been worse,” Paerl said.

Two months later, Hurricane Irene ripped through the Pamlico Sound. A day later, the ferries were on the water as usual, and though FerryMon’s instruments were still on board, Paerl could collect only a few samples from the ferry that crossed the Neuse Estuary using money he received from a small National Science Foundation grant.

Those data have proved inconclusive. The state has lost its best method for measuring the health of an ecosystem that’s home to the largest fish nursery on the Eastern Seaboard.

According to a state mandate, there can be no more 40 micrograms of chlorophyll A per liter of water in North Carolina estuaries. The FerryMon data set was the best way to determine if that criterion was being met.

“We have very little idea what Hurricane Irene did to the Pamlico Sound last summer,” Paerl said. “And that’s really a shame, because if you want to look at water quality trends you need a continuous set of data over the course of years.”

Paerl, who last August was honored with the Odum Award for Lifetime Achievement from the Coastal and Estuarine Research Federation, hopes to regain funding.

At 64, he still has a passion for being on the water, but he spends a fair amount of time trying to get FerryMon back on line for 2012.

“You should know,” he said, “I’m a pit bull when it comes to this stuff.”