Bryan applies dendrochronology techniques to growth increments formed in the hard parts of marine and freshwater species including fish, bivalves, and corals. These aquatic chronologies are used to establish long-term patterns in productivity and their relationships to climate, quantify long-term impacts of human activities, and hind-cast climate prior to the start of instrumental records. They are also combined across species to describe linkages among marine, freshwater, and terrestrial ecosystems or to generate multi-proxy climate histories. Originally trained as a forest ecologist, Bryan also maintains interests in developing histories of forest disturbance and natural hazards including landslides and earthquakes.