Professor Johnson's research interests are centered on the impacts of environmental change on coral reef ecosystems. She uses a combination of field and laboratory based approaches to 1) evaluate and monitor the structure and function of coral reef ecosystems, 2) quantify inherent natural heterogeneity in key environmental parameters including temperature, dissolved oxygen, and pH , 3) explore the implications of environmental variability for ecophysiology of coral reef primary producers, 4) and determine the implications of local and global environmental change for these foundational coral reef taxa.

Professor Johnson's research includes taxa ranging from fleshy algae to corals, but she primarily focuses on calcifying algae - particularly crustose coralline algae. She uses calcifying reef algae as model taxa to identify and monitor coral reef ecosystem responses in an era of rapid environmental change.