Two years after the worst maritime oil spill in history, fishermen, scientists, and environmentalists up and down the US Gulf Coast warn that the disaster may be far from over.

Dead dolphins keep washing up on shore in unprecedented numbers.

Oil-coated coral reefs are dying in the deepwater.

Eyeless shrimp and crabs with holes in their shells are showing up in relatively empty fishing nets while killifish, a minnow-like fish at the base of the food chain, show signs of chemical poisoning.

And critics say offshore drilling safety and oversight remains woefully lacking.

"Politics continues to triumph over common sense. It's outrageous that so little progress has been made to make offshore drilling safer," said Jacqueline Savitz, senior campaign director at the environmental group Oceana.

"It's not a matter of whether there will be another oil spill, but when."

The April 20, 2010 explosion on the BP-leased Deepwater Horizon drilling rig killed 11 workers, blackened beaches in five US states and devastated the Gulf Coast's tourism and fishing industries.

It took 87 days to cap BP's runaway well 5,000 feet (1,500 meters) below the surface that spewed some 4.9 million barrels (206 million gallons) of oil into the Gulf of Mexico.

In an attempt to keep the crude from Louisiana's fragile coastal wetlands, BP sprayed chemical dispersants directly into the underwater gusher and onto the massive slick.

The dispersants -- along with favorable winds and currents, oil-eating bacteria in the Gulf's warm waters, the sheer distance of the well from the coast and a fleet of cleanup crews -- kept most of the oil out of the marshes and limited, to an extent, the immediate environmental impact.

Critics say however the dispersants made it harder to remove the oil from the ecosystem and created a dangerous chemical soup that was sent deeper into the food chain.

"The oil is still subsurface in the Gulf," said Wilma Subra, a respected chemist and activist who has been testing seafood and sediment samples collected across the Gulf Coast.

"The oil is still present in the wetlands and estuaries and on the beaches. People are continuing to get exposed."

Despite BP's public assertions that the Gulf is on the mend, Subra and other scientists insist it is far too soon to determine what the long-term environmental impacts will be.

"There are potential new impacts that we haven't even seen yet, but just based on the impacts we have seen it's going to be a long time before recovery sets in," Subra said, adding that the effects of the spill could continue for "generations."

BP has vowed to make residents of the Gulf "whole" and reimburse them for any "legitimate" economic damages.

On Wednesday, it finalized a $7.8 billion settlement deal to settle thousands of claims from fishermen and others and has already paid out $6.3 billion to people and businesses who chose to sidestep the court process.

It has also pledged $1 billion to early restoration projects and will likely be required to spend more once a lengthy environmental impact study is concluded.

"From the beginning, BP stepped up to meet our obligations to the communities in the Gulf Coast region, and we've worked hard to deliver on that commitment for nearly two years," BP chief Bob Dudley said in a statement.

"The proposed settlement represents significant progress toward resolving issues from the Deepwater Horizon accident and contributing further to economic and environmental restoration efforts along the Gulf Coast."

Theresa Dardar is among those who lives have been changed by the drilling disaster.

She lives in Bayou Pointe-au-Chien, a Native American fishing community on Louisiana's Gulf Coast her family has called home for 300 years.

Dardar and her neighbors have watched their coastal lands get slowly swallowed by the sea after canals built by the oil companies brought salt water into freshwater marshes.

Now she fears that her family's livelihood could disappear.

"How are you going to make us whole if we lose our fishing industry?" she asked of BP. "I don't think they can answer me," Dardar told AFP.

That fear is echoed in coastal communities across the Gulf Coast.

"We're suffering," said George Barisich, president of the United Commercial Fisherman's Association.

Despite the checks rolling in from BP, Barisich said some fishermen could still end up losing their homes.

Many were just getting their finances back on track after the devastation of Hurricane Katrina in 2005 when the BP spill closed a third of Gulf waters to fishing.

While the waters may be open now with assurances that the seafood is safe to eat, prices are down, costs are up and the harvest has been disappointing.

A third generation fisherman from St Bernard Parish south of New Orleans, Barisich employed eight people and pulled in annual profits of up to $100,000 in the years leading up to the spill.

Last year he had two employees, and he lost $40,000. He blames BP.

[Photo of a dead fish laying on the sand with oil residue via AFP Photo/Joe Raedle]