BLUE HILL, Maine — A year after the explosion on the BP-Deepwater Horizon offshore oil rig in the Gulf of Mexico,  the oil that spewed from the damaged rig continues to have an impact on the Gulf Coast environment, marine life and coastal residents, according to a Blue Hill scientist.

“We hear about other disasters, and we tend to forget about the gulf,” said Dr. Susan Shaw, a marine toxicologist and executive director of the Marine Environmental Research Institute in Blue Hill. “This is the biggest disaster in this country in our lifetime, and it isn’t over. The oil is continuing to wash up on shores.”

Shaw dived in the gulf last July while oil was still gushing from the damaged oil rig and was there again last September. She returned March 12-13 to continue collecting samples for MERI’s Gulf Eco-tox Project, an independent investigation into the effects of oil and chemical dispersants on marine life.

The Deepwater Horizon was damaged in an explosion on April 20, 2010, that killed 11 workers  and sent an estimated 205 million gallons of oil into the gulf.

“I wanted to see, almost a year after the explosion, what was happening there,” Shaw said Wednesday in a telephone interview from New York. “I went hoping to find recovery. But I found the presence of oil everywhere I went. It was very disturbing to find so much oil in the food chain.”

Barataria Bay in Louisiana, is a heavily oiled area, she said. The marshy areas are black with oil, and very little is  living there. Also, very few birds live in the area, where thousands of coastal birds once came to nest. During her time there, Shaw said, she saw only seven birds.

“All the small creatures that should be there in the sand — the mussels and crabs — are all dead,” she said.

The scene at  Grand Isle State Park, also in Louisiana, appears to be almost normal, with white sand beaches stretching along the shore. But beneath the surface, there is oil.

“If you dig 6 inches down in the sand, there is black, sticky oil bubbling up,” Shaw said. “The area is still restricted, because there is so much oil just below the surface.”

The problem is not only below the surface. In the tidal pools nearby, she said, there was a sheen of oil on top of the water. That sheen poses a danger to the dolphins that regularly visit the area, she said.

At Grand Isle, dolphins visited the lagoons near where Shaw was collecting specimens.

“It was tragic, really,” she said. “ They were feeding and jumping there behind me, and I realized they were feeding right into the oil.”

Researches already have documented 400 dolphin deaths along the coast, including 100 just since January. Half of those were baby dolphins that either were stillborn or newborns, she said.

It is still early in the dolphin calving season in the gulf, she said, and, within the next six weeks or so, between 3,000 and 5,000 dolphins are expected to calve in the region.

“We’re quite concerned that the number [of dolphin deaths] could be into the thousands before the end  of calving,” she said. “This may be just the tip of the iceberg.”

Other researchers have documented  plumes of oil and dispersants, the chemicals used to break up the oil spills on the surface, in the water column and oil deposits that have created dead zones on the sea floor.

“The dispersant-oil mix is extremely toxic, and it’s still in the gulf in large amounts,” she said.

Researchers are only beginning to see the effects from those deposits, she said.

The impacts are not limited to the environment and the small marine creatures. One of the most dire consequences of the oil spill may be its effect on the people living along the Gulf Coast who were exposed to the toxin.

During her recent trip to the gulf, Shaw said she interviewed a number of coastal residents, some of whom had participated in the cleanup often without proper protective gear. Many now are reporting serious health problems with symptoms that have included vomiting, breathing problems, enlarged hearts, weight loss, headaches and internal bleeding.

Shaw warned early on of the effects of the dispersants, and she reaffirmed that concern this week. Corexit 9524, the dispersant used early in the containment and cleanup effort in the gulf, contains chemicals that, she said, can attack red blood cells and cause internal bleeding.

She said that doctors in the gulf area have found evidence of oil-dispersant chemicals in blood samples taken from residents there. Those types of health problems are likely to continue, Shaw said.

Shaw called for governmental action in the gulf. She said the nation needs to invest more resources into research in the gulf to study the impact of the oil spill and also needs to take legislative action to prevent other such accidents from happening.

“We need some policy action to protect the American public going forward,” she said. “This could easily happen again. Offshore drilling is going on, and new leases are being issued. We need to make sure that it’s going to happen safely.”