Q&A

Which trees are most prone to lightning strike, and what do sea snakes drink?

The Exxon Valdez disaster 30 years ago left Alaska’s Prince William Sound smothered in 11 million gallons of crude oil. Because the area’s wildlife varies in terms of diet, habitat niche and reproductive rate, species were affected very differently. Some barely suffered losses, while some, such as bald eagles (250 dead), rebounded quickly. Others, such as sea otters, harbour seals and harlequin ducks took much longer. Clam beds and Pacific herring, which spawn in the shallows and sustain seabirds, whales and fishermen, still show few signs of recovery.

Some interesting patterns have emerged since the spill, though these could also be attributed to climate change. Species feeding on crustaceans on heavily oiled shore sediment, for example, suffered more than those dining on fish or zooplankton in deeper water. Behavioural changes have also occurred – Dall’s porpoises now frequently enter the Sound’s confined, shallow bays to hunt fish, because the number of patrolling orcas, which prey on the porpoises, plummeted beyond recovery.