Robert Paine, a groundbreaking, hands-on ecologist who found that removing what he called a “keystone species” from an environment could profoundly affect the fortunes of neighboring species, died on Monday in Seattle. He was 83.

The cause was acute myeloid leukemia, his daughter Anne Paine said.

Dr. Paine demonstrated in his field work that certain species exert a disproportionate impact on their ecosystems and that their elimination — as a result of climate change, pollution or some other natural or man-made factors — can produce unexpected and far-reaching consequences for the local environment.

A teacher and researcher at the University of Washington for 36 years, Dr. Paine propounded his keystone theory in 1966 after studying ochre starfish, or sea stars, as they preyed on the mussel population along the rocky shore of Makah Bay, on the tip of the Olympic Peninsula in Washington State.

After he pried the starfish from rocks with a crowbar and hurled them into the sea, the mussels proliferated along the shore, displacing algae and limpets.