Marine ecologist whose students went on to become respected leaders in their field
Bob Paine, who has died aged 83, was a marine ecologist who coined the term "keystone species" to describe animals and plants whose loss can wreak havoc on an ecosystem.
The keystone concept took the field by storm in the late 1960s, when Paine described removing dozens of Pisaster ochraceus starfish from the rocky intertidal zone of Makah Bay in Washington state. The starfish was the main predator of the mussel Mystilus californianus, which took advantage of its absence to invade, occupy and dominate, resulting in the total number of species living on the rocks halving.
Paine described this "trophic cascade" in a 1966 paper in American Naturalist entitled "Food Web Complexity and Species Diversity". In 1969 he defined a keystone species as one that determines "the integrity of the community and its unaltered persistence through time".
Scientists soon described other keystone species, such as the sea otter. In the early 1970s it was found that after Aleut islanders hunted the otters or drove them away from certain Aleutian islands off the coast of Alaska, sea urchins - a favourite otter food - began to proliferate, destroying swathes of Pacific giant kelp forests and the fish living in them, resulting in fish-free "urchin deserts".
Robert Treat Paine was born in Cambridge, Massachusetts, and was fascinated by nature from a young age. After taking a degree at Harvard, he moved to the University of Michigan to do graduate research on fossils, but switched to studying living animals after attending a lecture on freshwater invertebrates.
From 1970, much of his research was carried out on Tatoosh Island, an uninhabited rocky island off the Washington coast.
There he repeated his starfish-removal experiment on a bigger scale.
Paine was never happier than when scampering over barnacled rocks, accompanied by students, many of whom went on to become leading ecologists.
He continued to teach beyond his official retirement in 1998. In 1995 he had finally allowed starfish to return to the Tatoosh shore after 25 years of exile.
"I thought, I'm not going to live for ever, so let's see what happens if I let the starfish back," he said. He was delighted when their numbers rebounded.
Paine's marriage to Alice Coleman was dissolved. He is survived by three daughters.