Freshwater Ecology Practice Test

In ecology, a community is the assemblage of living organisms from different species that inhabit the same area and interact with one another. In a stream with several species of macroinvertebrates and fish, all those living organisms together form the stream’s community because they coexist and interact within that habitat.

This is different from a population, which is all individuals of a single species in an area. It’s also different from a species, which would refer to just one kind of organism. An ecosystem goes a step further by including the physical environment and the flows of energy and nutrients that connect the living and nonliving parts. Since the focus here is on the living, interacting groups, the best term is community.