freshwater ecosystems, biogeochemistry
Cole is now an emeritus scientist. During his active research career, Jonathan Cole studied the sources of carbon and its movements in rivers, lakes, and estuaries. Cole focused on the connections between these ecosystems and their surrounding watersheds. He and colleagues have shown that at a global scale, up to 50 percent of the carbon that is stored in soils is eventually exported to streams, rivers, and lakes, in the form of particles and dissolved organic matter or turned to carbon dioxide in these inland aquatic environments.
Because of the transfer of land-based carbon to surface waters, the food webs of aquatic ecosystems are often partially supported by their watersheds. Working in both the Hudson River and in Wisconsin lakes, Cole and colleagues determined the size of this subsidy to fish populations and to invertebrate consumers. To put the question in simple terms, are fish and other aquatic consumers made of carbon that originates from aquatic plants or maple leaves?
To date, Cole’s research has shown that a surprisingly large fraction of the biomass of fish (and of the aquatic invertebrates they consume) is derived from land-based carbon. Using ambient radiocarbon (carbon 14), Caraco and Cole have determined that organic carbon in the Hudson River is 1,500 to 5,000 years old. Some invertebrates in the Hudson consume this ancient carbon. Thus, the food web in the Hudson is connected to carbon that was sequestered on land thousands of years ago.
Studies of food webs appear solely academic, but these answers strike a chord with fishermen. As fishing is the second largest recreational activity in the United States being able to talk with fishermen about where their fish come from offers an exciting opportunity to educate and interest a significant public group about ecology.
One of the key ways of mitigating climate change is to keep carbon away from the atmosphere where it is found as carbon dioxide, a key greenhouse gas. Carbon that is stored in trees and other woody plants, in soils, and in the oceans is said to be sequestered.
Most of us are familiar with the idea that we need to reduce carbon dioxide emissions to prevent global warming. Methane is also a problem, and we hear about it much less frequently. But compared to carbon dioxide, methane's impact on climate change is some twenty times more powerful.
Most of us learned about the aquatic food web in high school. Using a sealed aquarium, teachers explained that plants form the base of the web, with the organic carbon they create supporting aquatic life—from invertebrates to sport fish.