Most of the research of Stefan Garthe is dedicated to the role of seabirds in coastal and marine ecosystems. Central research questions include:

• What are the main habitats used by seabirds in offshore and coastal areas of North and Baltic Sea?
• What are the spatio-temporal patterns of seabird distribution?
• What are the foraging strategies of various seabird species?
• What can we learn from seabird behaviour to detect and understand changes in the marine environment?
• To what extent do offshore wind farms, fisheries, ship traffic and litter effect the environment?