Exploring the Rutgers Marine Field Station at the Edge of the Marsh

Sep 20, 2017
Photo by: Pat Johnson Walking across the wooden bridge to the RUMFS; the day started foggy.

Once a year, the scientists at the Rutgers University Marine Field Station open their doors to their neighbors in Little Egg Harbor and Tuckerton, and they come by the dozens, sometimes the hundreds – even when these neighbors have to drive down Great Bay Boulevard, over four wooden one-lane bridges to the end of the road and the edge of the sea, and then trek a quarter-mile wooden trestle bridge over the marsh to what was once an old Coast Guard station. It’s always worth it.

On Sept. 16, volunteers with T-shirts and wide smiles plus on-site manager Roland Hagan greeted the early birds who arrived right at 10 a.m. despite the foggy conditions this year. Hagan had a branding iron made of the RUMFS logo and burned the image into old shingles taken off the roof of the station’s boat house. “We have hundreds of them.” He was selling them for $20 each as a fundraiser for the station.

While waiting for the first history of the station lecture to begin, guests were able to wander through exhibits. The technicians working at the station spent last week collecting live fish samples to educate visitors about what lives in the Mullica River watershed and Great Bay. Technician Ryan Larum explained that the large sheepshead fish in the tank, a thick chunk of a fish, was a special find because they are usually too fast to get caught in the trawling net. “We must have surprised him,” he said. There was also a summer flounder (fluke) trying to mimic the bottom of the tank, but it was only partially successful as a snub-nosed ray kept nosing around and forcing it to move on. The agitated ray would also swim near the edge of the tank and put its head out of the water: “He has extra sensors on his snout so he’s trying to determine where he is,” said Larum.

Technician Mattea Berglund was explaining one of the traps the technicians use to gather fish from offshore reefs. The trap is not baited, but the structure intrigues the fish. There are two net structures inside the trap. One the fish can pass in and out of, giving them a sense of false security; the other has a net door that falls shut once they pass through. The trap is left for about a week and can catch up to 100 small fish, such as tautog, black sea bass and scup.

In another exhibit, we learned the RUMFS is doing a great deal of research on otiliths, the ear bones of fish. For the first few months of life, fish ear bones create growth rings much like the growth rings of trees. Marine biologist Paola Lopez and technician Jessica Valenti said the growth rings are able to tell them what rivers the fish were spawned in and how old they were when they moved out to sea.

“The chemical composition in the rings holds information on the salinity of the water,” said Lopez. For this particular study, the RUMFS is asking fishermen who see or catch small striped bass in brackish or fresh waters to report it on the website sej.stripers@gmail. “Of course they will return the fish, as they will be too small to keep,” said Lopez.

The three major spawning areas for striped bass are the Chesapeake Bay, and the Delaware and Hudson rivers, but there are smaller spawns in the Mullica, Raritan, Navesink and Shrewsbury.

Ken Able’s lecture was on the history of Station 119, the number given the building when it was built as a Coast Guard station in 1937. It was decommissioned in the 1960s and was vacant when fire destroyed much of the interior in 1965. In 1972, Rutgers University took a $1-per-year lease from the state and began rebuilding the station as a marine science laboratory, using the original blueprints for the Roosevelt-style building. In 2002, the university took complete possession, said Able.

The earliest research was on the salt marshes. “The grass fuels the entire (Mullica River basin) system. When it dies and starts to decay, microbes feed on it, and other organisms feed on those, and on up the food chain. Much of what grows in the estuary depends on the growth of that grass.”

Able is a fish biologist; much of his research is on the marsh “nursery,” where important food species of fish that spawn in the ocean spend their critical first years.

Each of the 52 weeks, for 28 years, the scientists and technicians at the RUMFS have collected larval (baby) fishes in a net off the bridge over Little Sheepshead Creek to take back to the lab for sorting and counting. This continuous effort, the longest on the East Coast, has recorded the changes in number and types of fish using the marsh nursery.

In addition to studying fish beginnings, the station has immediate access to sharks, harbor seals and bottlenose dolphins that swim into the boat basin or even under the station.

“During flood tide, fish swim under the station. For a fish biologist this is great; you can’t get any better than that.”

The station’s advanced technology employing underwater robotics to track fish is one of the reasons the scientists and technicians have traveled the country. Science is almost always driven by funding, explained Able, so they have gone to work in New York Harbor, Delaware Bay and Maryland, as well as to Louisiana after the Deep Water Horizon oil spill, Alaska and the U.S. Philippines.

The biologists have implanted ultrasonic tags in certain fish species they are studying for “site fidelity.” Some fish, such as striped bass and flounder, have returned to the same place year after year. They know this because they have set up underwater listening devices that act like an E-ZPass system. The fish don’t hear the sonar tings as they pass by, but the scientists can pinpoint where a fish has been.

“Biologists in Maine have installed the same system in the Saco River,” said Able. “We were surprised to find that some of our fish went to Maine and some of their fish came here, and some of our fish went to Maine and then came back here.”

Another experiment using technology employs an underwater submersible named REMUS. “The robotic hydroplane has the ability to control its own buoyancy,” said marine biologist Thomas Grothues.

REMUS can function for 14 hours before it needs to be re-powered. Grothues and others used the robot in Alaska for a study of juvenile salmon. “The question was how fast did juvenile salmon (called ‘smolt’) move from fresh water into the ocean. REMUS could track them in water 600 meters deep.”

Transmitters were biologically implanted in the fish, and each fish had its own transmitter code. REMUS had an on-board library of the codes and could track an individual fish once upon hearing its ID “chirp.” REMUS could hear the chirps from as far as a half-mile.

At the same time as it was tracking and reporting the movements of fish; REMUS would take samples of salinity, temperature and chlorophyll (from plankton). “It’s like a Swiss Army knife,” joked Grothues.

The study found that salmon smolt could chemically change their cells and organs to tolerate salt water within two days.

Technician Stacy Van Morter held small jars packed with juvenile fish that had been captured in the weekly netting as described by Able. One jar was full of baby menhaden, or mossbunker, captured in a net sweep one week in June. From the consistent netting project off the bridge near the station, the scientists have found that menhaden are prolific, “spawning all the time,” said Van Morter. The second jar held baby crabs, goby and anchovies.

Another wonder of the deep was illustrated in a painting of a fish at the bottom of a burrow. Able explained that the tilefish – a commercially caught fish – digs a burrow in the bottom of the ocean that can be 6 feet deep. The burrows are also utilized by lobsters and other sea creatures. “That’s why they don’t catch tilefish in nets; they have to fish for them,” said Able.

The RUMFS open house happens only once a year, but it’s like Christmas or a birthday party for a marine science nerd.

— Pat Johnson


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