A Sea in Flames - Carl Safina [92]
Science bulletin: scientists with the University of Southern Mississippi and Tulane University report finding petroleum droplets on the fins of small larval fish. “Their fins were encased in oil,” says Harriet Perry, director of the Center for Fisheries Research and Development at the Gulf Coast Research Laboratory. “This is one route up the food ladder,” she speculates. “Small fish will eat the larvae, bigger fish—you know how it goes.”
Laboratory studies and field experience with wildlife shows that oil can cause skin sores, liver damage, eye and olfactory irritation, reduced growth, reduced hatching success, fin disintegration, and, of course, death. In heavily oiled areas, some animals can move away. Fish eggs and larvae cannot move. The Argo Merchant oil spill killed 20 percent of nearby cod eggs and almost half of pollock eggs. The Torrey Canyon killed 90 percent of the eggs of a fish species called pilchard. Similar death rates followed the Exxon Valdez. Other species seem far less affected. Of oiled fish eggs that hatched, larvae often had deformed jaws, spinal problems, heart problems, nerve problems, and behavioral problems.
However, under normal circumstances in clean water, natural mortality rates of eggs and larvae are so colossal, and such a tiny fraction survive to adulthood, that even the near-total destruction of one whole year-class of fish eggs by an oil spill might have a difficult-to-notice effect on adult populations.
In Prince William Sound during the months following the Exxon Valdez spill, herring eggs and larvae in oiled areas died at twice the rate they did in unoiled areas. Larval growth rates were half those measured in other North Pacific populations. Herring larvae also suffered malformations, genetic damage, and grew slower than ever recorded anywhere else. Those problems were gone by the following year.
But it’s not that simple. Different things get hurt at different rates for differing periods of time. Oil that works its way into sediments and under boulders remains toxic and available to living things. In Prince William Sound after Exxon Valdez, oil hiding beneath mussel beds continued to find its way into the region’s animals and their food web. For years, ducks and otters suffered chronic exposure to oil. For at least four years, the eggs of pink salmon, which spawn in the lower reaches of streams, near seawater, failed at abnormally high rates. Young sea otters born for several years after the spill survived at unusually low rates. After sea otters had received protection from hunting for their fur, their population increased 10 percent annually. But after the oil spill, they recovered at only 4 percent per year. In heavily oiled areas, their numbers did not increase at all for at least a dozen years. Shellfish—which sea otters (and people) eat—concentrate oil hydrocarbons quickly and metabolize them slowly. For at least several years, black oystercatchers fed their chicks more mussels but achieved less growth than normal. Harlequin ducks (probably the world’s most exquisitely beautiful sea duck, which is saying something) for many years suffered low weight as their bodies tried to fight the toxic effects of the petroleum hydrocarbons they were getting in their food. In parts of Prince William Sound, they died at rates of 20 percent annually for over a decade. A study published in the April 2010 issue of Environmental Toxicology and Chemistry finds that harlequin ducks are still ingesting Exxon Valdez oil. Biopsy samples show their livers containing the enzymes they produce when their body is wrestling with oil.
Everywhere I’ve been, there’s boom. Boom along the shore, boom under bridges, boom in roadside canals. Boom, boom, boom. You can’t avoid it. And almost everywhere I’ve been, there’s been the chronic low-level hassling of camera-toting types like me, by sheriffs and orange-vested private guards on public roads and alongside waterways.
And today, the Coast Guard takes the situation one giant step