The study looked at fish diversity in the Indian River Lagoon, FL, USA over 21 years. They found that the fish community and the biogeographic transition zone shifted northward by 9-21 km in years with fewer disturbances. If this trend continues, fish communities could shift 111-243 km by 2100. The changes in diversity were linked to temperature and dissolved oxygen levels in the environment. The shift in species assemblages was driven by changes in the physical environment, with species sorting playing a key role.