"We're probably going to feel the impacts for decades," he said.
He charged that, despite heavily publicized images of suffering animals, BP was downplaying the horrors he has seen every day in the ocean.
"What we've been seeing and hearing from BP and sometimes the government has often been very different from what independent scientists are saying."
But BP spokesman Curtis Thomas said the company is taking wildlife research seriously and has just begun using a recently approved $500 million research grant that will study not only the habitats but effects of the oil and dispersants.
Thomas said that for groups that have a specialized interest, BP's response will not be enough. Some, he said, have called out the company for doing too much for the wildlife when there is so much to be done elsewhere.
A double boom system set out by BP around Queen Bess and Cat islands, one to block the oil and one to absorb oil, had trapped enough oil to darken both booms, but oil slicks could still be seen lapping at the shores where the birds had built intricate nests.
The grasses around the sensitive island marshes have already been coated with oil and will eventually die, Hocevar said, depleting a food source and forcing the thousands of birds that live there to find sanctuary elsewhere.
Hocevar said he's already seen some evidence that the dolphins and some birds are starting to change their behavior patterns, moving closer to shore to stay ahead of the oil.
"But as it moves ashore there's no place for them to go," he said.
Hocevar said the sheer size of the spill and what Greenpeace believes to be contamination of the entire water column, from sea floor to surface, all but ensures a years-long process to return balance to the waters.
"Unfortunately the damage has mostly been done," he said.