Ships of Opportunity

Using NC Ferries to Monitor the Pamlico Sound p.2

The nutrients support the vibrant food chain that makes the Pamlico Sound so ecologically important. Fish may spawn offshore, but their larvae drift through the sound to spend their juvenile years in its protective nurturing environment. Predators generally stay away, both because its turbidity interferes with visibility and because its shallowness would limit their maneuvering space. As the juvenile fish reach maturity "they swim out of the system," Ramus says. "So it's really like an incubator."

But too many nutrients, from natural sources as well as livestock and fertilizer runoff, can trigger explosive growths of algae. And influxes of other human-generated chemicals and toxins can further impair water quality.

With that in mind, Ramus and Paerl wondered about the impact of growing urbanization and more intensive agricultural operations upstream. "Beginning in the 1970s, there were tremendous land use changes in the watersheds that feed this system," he notes. Yet, "before we started our work, there was no scientific data about Pamlico Sound proper, certainly no systematic study on how it works.

"We had a system that is very important, and we perceived it to be at risk, with no information. What we needed was a system to fast-track the acquisition of data."

That's when he and Paerl began to think of the state's ferry system. Portable, automated sensors were becoming available that could be installed on the shallow draft vessels to monitor water conditions during daylight hours.

Repeatedly crossing major portions of the estuary from sunrise to sunset - even later on some shorter routes - these "ships of opportunity" could provide constant data on dissolved oxygen, salinity, temperature, turbidity, chlorophyll (algae) levels and other parameters for what turned out to be an initial cost of $40,000. As more were built and installed, per vessel costs would drop.

By comparison, it costs $1,000 a day to operate the R/V Susan Hudson, the Marine Laboratory's 50-foot research boat, and $10,000 a day for its 135-foot-long research ship R/V Cape Hatteras, he notes.

"Here we had this fleet of 24 vessels that are larger than the R/V Cape Hatteras and make frequent crossings on a route we can utilize for research purposes. So Hans and I began shopping this idea," he recalls.

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