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USF studies how water flows in Tampa Bay

USF studies how water flows in Tampa Bay

ABOARD THE R/V.W.T. HOGARTH A research vessel motored out of downtown St. Petersburg on its back deck, loaded with concrete trapezoids and squat.

The blocks were painted blue and marked USF and FDEP. They were essentially anchors and weighed 2,500 pounds each. A small, $18,000 sensor was hidden within each block.

Bob Weisberg, a physical Oceanographer at the University of South Florida was on deck, along with a group of students and colleagues. They wore orange vests with hard hats and carefully walked around the trapezoids.

Over the 78-foot R/V W.T. HogarthThe bay, with its gunwales, slipped quietly by, reflecting the morning sun on Tuesday in May.

Soon, the researchers will transport the sensors to the bottom bay. There, they will spend months measuring the velocity of water. The work is being funded by the Florida Department of Environmental Protection.

Scientists need velocity data in order to better understand a bay aspect Weisberg believes is underappreciated: its movement.

Many scientists and advocates are concerned about the nutrients polluting the bay from sewage, fertilizer, or other runoff. Weisberg stated that people don’t think like Weisberg. It is also about the currents, tides, and other factors that cause this contamination.

Where does all of this stuff go anyway? He asked rhetorically. Everything else flows out of the circulation.

Bob Weisberg, a University of South Florida physical oceanographer, stands on the top deck of the R/V W.T. Hogarth research vessel on May 3.
Bob Weisberg is a University of South Florida physic oceanographer who stands on the R/V W.T. Hogarth research vessel May 3. [ DOUGLAS R. CLIFFORD | Times ]

The estuary is more like an open road than a stagnant tub. Water is constantly moving. The sea is constantly moving due to tides and winds, while freshwater flows out of rivers like the Hillsborough, colliding into the briny gulf.

Scientists struggled to track down the impact of a 215-million-gallon wastewater discharge from the Piney Point fertilizer plant site on the environment made it clear how important circulation was. Weisberg and his students had created a model years ago. The pollution could have moved through Tampa Bay.

It was important to know where these contaminants ended up. They may have fed the Red Tide bloom which plagued the region last year.

Weisberg was confident with the model before Piney Point. But his team wanted more data to verify it. They had previously verified the accuracy of the model. For observations from a monitoring station located below the Sunshine Skyway bridge.

The R/V W.T. Hogarth research vessel, full of USF College of Marine Science researchers, was positioned near a drop point for an ocean circulation sensor on May 3.
The R/V W.T. The Hogarth research ship, which was full of USF College of Marine Science scientists, was positioned at a drop point for an Ocean Circulation Sensor on May 3. [ COURTESY OF BEN MEISTER | Courtesy of Ben Meister ]
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Piney Point was an environmental crisis in the region but it proved to be a boost to science. It highlighted the importance for consistent research and offered a unique opportunity to study wastewater discharges.

The USF researchers pitched the Department of Environmental Protection to install four current monitors in shallower locations than the bay’s main shipping channel. The team will also deploy sensors that monitor water quality metrics such as pH and salinity.

Related: What we know about Piney Points effect on Tampa Bay

Jay Law, a physical Oceanographer and head operations in Weisbergs’ lab, stated that the first year of equipment buying and deployment will cost approximately $395,000.

Weisberg stated bluntly that Piney Point is the reason behind this funding. He was on his last research cruise before retiring.

Thomas Frazer, USFs College of Marine Science dean, stated that scientists are always responding in some way to environmental disturbances. He said Piney Point was an example of where they could improve their data collection and monitoring.

An ocean circulation sensor is prepared for deployment on the deck of the R/V W.T. Hogarth research vessel. The sensor will help sharpen a model that tracks the circulation of water through Tampa Bay.
A sensor for ocean circulation is ready to deploy on the deck of R/V W.T. Hogarth research vessel. The sensor will sharpen a model that tracks water circulation through Tampa Bay. [ DOUGLAS R. CLIFFORD | Times ]

The Hogarth They chugged for hours on four Coast Guard towers raised platforms, topped with metal spires, where the researchers chose the monitors to be deployed.

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The crew used a winch and concrete trapezoids to lift them off the deck. The crew slowly lowered the blocks to the surface and then released each block from the winch.

Three divers jumped off the deck and swam below to free a harness from concrete, and to measure the depths of each sensor between 11-23 feet.

USF physical oceanographer Jay Law, left, drops into Tampa Bay while dive safety officer Ben Meister, center, prepares to leap from the deck of the R/V W.T. Hogarth research vessel on May 3.
Jay Law, USF’s physical oceanographer, descends into Tampa Bay, while Ben Meister (dive safety officer) prepares to jump from the deck of R/V W.T. May 3. Hogarth research vessel [ DOUGLAS R. CLIFFORD | Times ]

The technology should work smoothly once it has been deployed. Law stated that the monitors send six pings per hour for six minutes, one per second, every hour. These pings travel up into the water column, before reflecting off bits of sediment and plankton that are being swept by the current. The Doppler effect, which is the phenomenon that pings back at different pitches, is known.

Law explained that it is similar to hearing a train pass by. The pitch changes.

This pitch variation is used by the monitors to calculate the speed of sea currents. Law stated that the researchers will be able to retrieve data from memory cards after about four months. They will then compare their observations with their model and refine it as necessary.

Jay Law, a physical oceanographer with the USF College of Marine Science, left, and Matt McNamee, a USF undergraduate student, inspect equipment and perform depth measurements while deploying an ocean circulation sensor in Tampa Bay.
Jay Law (left), a physical oceanographer at the USF College of Marine Science and Matt McNamee (right), inspect equipment, perform depth measurements, and deploy an ocean circulation sensor to Tampa Bay. [ COURTESY OF BEN MEISTER | Courtesy of Ben Meister ]

Weisberg used the model to forecast storm surge. He was once a police officer who helped determine if a body washed ashore from a nearby marina.

He stated that additional data would increase confidence in the model and give more definitive answers about water movement in different parts of the bay. He expects that there will be unexpected questions.

He stated that his lifelong involvement in science has taught him a fundamental principle: The more information you have, the more you realize the amount you don’t know.

Take a look at the model

Visit the USF Ocean Circulation Labs Model, which includes a Red Tide Forecast.

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