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How oil spills harm birds, dolphins, sea lions and other wildlife

Ocean creatures that swim in deep waters are less affected by spills. But oil disasters near coastlines often do the most harm to shorebirds and marine mammals who live at the ocean’s edge and on its surface.

“These critters are living right where the floating oil accumulates,” says ecologist Sean Anderson, a professor of environmental science at California State University Channel Islands, adding, “This oil is toxic to everything.”

Here’s a closer look at how some species of marine life are affected by oil spills.

And if you want to help wildlife rescue efforts in the wake of the spill, you can donate here.


A cormorant is covered in oil after the sinking of the tanker Amoco Cadiz caused a massive oil spill off the coast of France in 1978.

Coastal birds can be especially vulnerable because the oil covers the surface of the ocean, where they feed, and washes onto beaches, fouling their nesting areas.

In California this most often affects brown pelicans, grebes, gulls, cormorants, plovers and other birds.

When birds become covered in oil, it renders their feathers useless for keeping them insulated and warm. Birds also instinctually preen themselves to remove anything on their feathers, which exposes them to ingesting toxic amounts of oil, Anderson says.

“The visuals are heartbreaking,” says Anderson. “Even a person who knows nothing about biology can see how birds are affected.”

Oiled birds returning to their nests also can contaminate their eggs and chicks with oil.


Bottlenose dolphins swim in the oily waters of Chandeleur Sound, Louisiana, in May 2010 after the Deepwater Horizon disaster.

Dolphins are migratory and will often swim to safer waters if they smell or taste oil, Anderson says.

But the playful mammals have been sickened and killed by spills, which can spew toxic fumes from the petroleum chemicals floating on the ocean’s surface. Two dolphins were found dead after a May 2015 oil spill near Santa Barbara, California, according to the Center for Biological Diversity.


A humpback whale  swims through an oil slick in Skjalfandi Bay, Northern Iceland, in 2009.

Oil spills also can be deadly for blue whales, gray whales, humpbacks and other species. Exposure to toxic oil fumes has been recognized to kill whales and dolphins even years later, according to the Center for Biological Diversity.

Sea lions

A young California sea lion is washed at SeaWorld San Diego's Wildlife Care Center in 2015 after an oil spill in Santa Barbara.

Unlike dolphins, sea lions are territorial and less likely to flee their coastal region, even if it gets fouled with oil, Anderson says.

This makes them more vulnerable to being poisoned by oil, which can seep into their mouths when they break the surface of the water to breathe.

Sea otters

A rescued sea otter is washed by workers at an animal facility after the oil tanker Exxon Valdez disaster fouled the pristine waters of Prince William Sound, Alaska, in 1989.

The sea otter remains endangered after being targeted by hunters in the 1800s and early 1900s for its fur. The aquarium crowd-pleaser can be found in coastal waters of the Pacific, from Alaska to central California.

Oil can slicken otters’ fur, causing them to lose their insulation and die from hypothermia — much in the same way that oil harms birds.

Sand crabs

Sand crabs, also known as mole crabs, are common on many beaches -- and a key link in the food chain. This one is on a beach in Trinidad.

These thumb-sized critters burrow in the sand where surf breaks on beaches, making them vulnerable when oil washes ashore.

“They’re right in harm’s way,” Anderson says.

High concentrations of oil kill the adult crabs, while lower amounts can harm their babies and eggs. These invertebrates are a key element of our beach ecosystem because “everybody eats them,” Anderson says. “They are incredibly important to a range of species.”


An oil-covered lobster lies dead after an oil spill off Refugio State Beach in May 2015 near Santa Barbara, California.
Trace amounts of oil in seawater can kill larval lobsters while they are still plankton floating in the water, according to the Gulf of Maine Research Institute.

As a result, an oil spill could potentially devastate a region’s lobsters — and its lobster fishing industry — five to seven years later, when those larval lobsters would have reached market size, the institute says.

Fish species

A school of rockfish swims near the base of an oil platform off the coast of Ventura, California, in 2003.

Some thicker oils sink to the bottom of the ocean, where they are ingested by rockfish, white croakers and other species that feed in the ocean’s depths.

The oil won’t necessarily kill them, Anderson says, but the toxins accumulate in their livers and other organs, making them unhealthy for humans to eat.

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