Richard Collins: The worst single-species die-off in the modern era

Millions of seabirds and other wildlife have been affected by 'the blob' — seal, sea-lion, cod, and humpback whale numbers have fallen drastically  

U.S. Fish and Wildlife Service: "In 2015, Alaska's common murre seabird colonies fell eerily quiet. Working with partners, scientists at Alaska Maritime National Wildlife Refuge have spent years documenting what happened next: the largest single-species wildlife die-off ever recorded in modern history." Picture: USFWS.

In October 2013, meteorologists discovered a large body of unusually warm water off Alaska. The annual cooling of the circulating ocean currents had failed to take place. Called ‘ the Blob’, this strange ‘marine heatwave’ was up to 100 metres deep and 1,600kilometres wide. Its temperature was, on average, 2.5°C above normal. The Blob split into three separate masses, but remained intact through 2014 and 2015.

Warm water has a low oxygen-carrying capacity and so it supports a reduced nutrient load. Plankton density fell with the Blob’s temperature rise. Creatures feeding on it starved and famine spread up the food-chain.