CAPE MAY - The heavy shipping that produces urban pollution in the Delaware River near Philadelphia usually isn't a problem downstream, at the mouth of the Delaware Bay.
But scientists want to know how other activities - including species habitat destruction and overfishing - may be affecting the vast estuary, and how the exchange between the two waterways affects the quality of brackish flow.
This summer, a research team from the University of Delaware's College of Earth, Ocean and Environment installed a data-collection device aboard the Twin Capes, one of the vessels of the Cape May-Lewes Ferry, operated by the Delaware River and Bay Authority.
The automated system provides real-time readings to the researchers and scoops up water samples that are taken back to the university's laboratory for further analysis.
With the aid of the device, the SeaKeeper 1000, more detailed data on the water exchange at the mouth of the bay has been gathered than in all previous monitoring and sampling done in the region over the last 50 years, said Jonathan Sharp, an oceanography professor at the University of Delaware.
The Twin Capes does not run year-round, so the monitoring will be mothballed for the winter.
Sharp, who has been studying the estuary of the Delaware River and Bay for more than three decades, came up with the idea of using the ferry to collect the data after realizing that the vessel makes up to eight crossings a day and could easily provide real-time readings.
"A research understanding is necessary to eventually provide a routine monitoring capability to assist in managing the valuable resources of the Delaware estuary," said Sharp, who is being assisted by doctoral student Yoana Voynova on the project.
Research groups under Sharp's tutelage have taken hundreds of cruises up and down the river and bay over the years to study the estuary, but none of the sampling has provided enough data to get a true read on the water exchange, he said.
The research aims to chart new pollution and how it affects the salinity and oxygen levels of the water, which in turn affect the creatures that live in the bay - horseshoe crabs, tuna, striped sea bass, weakfish - and the plankton they feed on.
Sharp said the project has garnered more exciting information than expected.
"We are finding even larger variations than we expected," he said of the water's salinity and oxygen levels along the path of the ferry.
"In addition, the monitoring is occurring over the time of extreme water inputs from Hurricane Irene and Tropical Storm Lee. We are probably going to have an interesting picture of this impact," he said.
The SeaKeeper 1000, built by YSI Inc. of Yellow Springs, Ohio, which develops and manufactures sensors, software, and data collection platforms for water quality monitoring and testing, is an automated system for monitoring both the ocean and the weather.
The components of the system, including a computer controller, a pump, and water quality sensors, are contained in a platform mounted below decks in the engine room of the vessel.
A companion meteorological system, to record air temperature and wind speed, has been mounted above the Twin Capes' pilothouse.
As the ferry glides across the bay, making round trips between Cape May and Lewes, Del., small gate valves in the hull pump seawater into the SeaKeeper 1000. Sensors measure the water and then log the data.
The system also records the temperature and salt content of the water, as well as the dissolved oxygen levels and the chlorophyll content.
Those readings help determine the ratio between the microscopic plants and animals living in the water and the oxygen content, which in turn helps gauge the health of the bay and the river.
The data can be remotely accessed by the University of Delaware scientists and a copy is sent to the National Oceanic and Atmospheric Administration's volunteer Observing Ship Program. A $75,000 NOAA grant is funding the project, which is expected to last at least two more years.
If more funding is obtained, Sharp's crew hopes to make the data available to passengers aboard all the ferries to view at interactive kiosks.
"It is our hope that the data will ultimately help guide the future management and restoration actions to improve the Delaware estuary," said Chris Heyer, a manager for YSI.