Examining global warming’s impact on marine communities

Illustration: ammonites in the oceanEarth sciences Assistant Professor Christopher Junium is looking to our oceans’ distant past to gain insights about its future. By studying ancient warming scenarios preserved in rock in Utah and Colorado, as well as in Central New York, dating back some 400 million years ago—he hopes to make ecological predictions about the future. He is particularly interested in an oceanic anoxic (lack of oxygen) event from 94 million years ago, when dinosaurs roamed the Earth. It was a time of tremendous tectonic upheaval, augmented by warm temperatures and shifting sea levels.

The recipient of an NSF Faculty Early Career Development (CAREER) award, Junium will use the five-year, $524,000 award to study how marine communities respond to global warming, anoxia and ocean acidification. His project includes fieldwork in Utah and Colorado, where he will examine the effects of a 94-million-year-old oceanic anoxic event (OAE), as well as trips to Central New York’s Green Lakes and Clark Reservation state parks, whose lakes are highly anoxic and, in some ways, characteristic of an OAE.

“It’s generally thought that OAEs resulted from rapid increases in greenhouse gases, setting off massive changes in the Earth’s climatic and ecological balance,” says Junium. “Not much is known, however, about how marine life reacted to these changes. The answer may lie in response to the question: ‘Who ate whom?’”

Using stable isotope analysis, Junium is making direct inferences about diet, trophic levels and subsistence in Cretaceous and Devonian food webs. “The stable isotopes of carbon and nitrogen basically follow what organisms consumed,” he says. “This is a relatively simple analysis in a modern ecosystem, but it’s far more challenging with 94 million-year-old material.”

Junium is working with scientists at Northwestern University, the University of Massachusetts Amherst, Williams College, Penn State, SUNY Oswego, the University of Delaware and Onondaga Community College (OCC).

He will also study the chemistry of Syracuse’s Green Lake and its sister, Glacier Lake, in Clark Reservation State Park, focusing on the nitrogen cycle—the process by which specialized bacteria convert nitrogen into a usable form, absorbed by plants and animals. Junium hopes his research will shed light on how the nitrogen cycle impacts bacteria near the bottom of the lakes.