'Oil spill raises concerns about aquatic food chain'

from billingsgazette........

"As whole cottonwood trees cartwheel down the Yellowstone River, it may take two to three weeks before biologists with the Montana Department of Fish, Wildlife and Parks can get out on the river in jet boats to assess the damage to wildlife.

“We haven’t seen 99 percent of the riverbank yet,” Bob Gibson, a spokesman for Fish, Wildlife and Parks, said Friday. “We can go to fishing access sites, but we can’t go to any of the islands, the braided back channels, the shallow waters.”

In high water, fish and many aquatic species head into those back channels, which is also where oil from the ruptured ExxonMobil pipeline oil has migrated.

In addition to the public’s concern over larger species, such as fish and birds, there may be a larger problem for small or microscopic organisms, like plankton, that small fish eat.

“The bottom end of the food chain is kind of where we’re worried,” Gibson said.

Some tiny organisms thrive and multiply in the presence of petroleum, depleting the available oxygen dissolved in the water and creating so-called dead zones, in which aquatic creatures cannot live because they lack sufficient dissolved oxygen in the water"...............READ MORE