CAMBRIDGE — After months of planning, three scientists from Horn Point Laboratory in Cambridge finally will begin their long-awaited research cruise to the Gulf of Mexico to study the effect of the oil spill caused by the explosion of the BP-leased Deepwater Horizon rig in April on animal and plant communities in the northern Gulf.

Mike Roman, Bill Boicourt and Jamie Pierson will begin their weeklong cruise today west of Mississippi. They’ll travel along the Louisiana coast into the waters off of Texas. This will allow the scientists to collect data from a large area to assess any effects from the spill, said Roman, director of the Horn Point Lab and leader of the trip.

They will be accompanied by scientists and graduate students from East Carolina University in Greenville, N.C., Oregon State University in Corvallis, Ore., and the University of Akron in Ohio, although Roman said Horn Point is the lead institution.

The cruise was made possible through a $200,000 Rapid Response Grant from the National Science Foundation, which Roman said was provided because of the strong data set that his lab has collected during previous research cruises in the Gulf.

The team has traveled to the Gulf for five years collecting data and assessing the effects of low oxygen bottom waters on fish and plankton in normal, healthy conditions. The idea now is to look at the same area and see what impact the oil is having on the ecosystem, said Boicourt, a physical oceanographer.

Although they’ve been there before, Roman said he, Boicourt and Pierson look forward to the trip and feel fortunate to have the background data to be able to assist in studying the effects of the oil spill.

Before the oil spill, Roman said, the problem of low oxygen bottom waters was getting worse, causing a decrease in the number of fish and plankton that were able to survive.

As a result of fertilizer and nitrogen phosphorous draining into the waters, phytoplankton grow wildly and bloom. Zooplankton feed on the phytoplankton, but cannot eat them all, so the phytoplankton sink to the bottom and rot, sucking up the oxygen and creating dead zones, said Boicourt.

The Horn Point team will focus on the continental shelf in the Gulf because that’s where a majority of the fish and plants are, said Boicourt. Ideally, Boicourt said, they hope to find no added harm to these areas from the oil, but if they do find problems, they hope to identify them.

If the crew finds that oil is affecting animal and plant life, Roman said, they will be able to measure the amount of oil in the water and find a correlation between it and the impact on aquatic species.

The team will measure varying conditions in the Gulf easily thanks to new technology. Boicourt said that instead of having to lower a probe while the boat is stationary, they have a ScanFish, which drags behind the boat collecting data of the water column in oceanographic, bathymetric and environmental monitoring applications.

Boicourt said they also have an optical plankton counter, which determines the size and density of the plankton in the water, and a Fluorometer, which determines how many plants are in the water by detecting chlorophyll. The Fluorometer can also detect oil, so the team will use it in their research.

The crew’s plans and expectations have been up in the air because they weren’t sure if the

oil spill was going to be contained or still flowing by the time they embarked on their journey, said Boicourt.

“I’m very happy we didn’t go out initially,” Boicourt said. “We’re interested in the effect of oil on the ecosystem, and it’s probably going to take time for that to occur.”