The ecologist changed from the study of community ecology to the study of ecosystem ecology
Community ecology is a branch of ecology that studies the interaction of different populations of organisms that make up a community and how these populations also interact with the abiotic components of their environment.
Thus, community ecology will study interactions such as food chains or food webs.
Ecosystem ecology, on the other hand, studies the interaction of different communities and how they operate as a system to achieve a kind of balance that is sustainable for every individual within the ecosystem. It involves the study of material cycling and energy flow within the ecosystem.
In other words, for the ecologist to have shifted from studying the food web interactions with a small pond to measuring carbon and nitrogen flowing through the water and pond sediment, they have changed from community ecology to ecosystem ecology.
More on ecology can be found here: https://brainly.com/question/18562569
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