The Long-Term Ecological Research (LTER) project was a multidisciplinary, multi-investigator program to investigate ecosystem dynamics in Antarctica. A central tenet of the PAL-LTER project was that the annual advance and retreat of sea ice is a major physical determinant of spatial and temporal variability and change in the antarctic marine ecosystem from total annual primary and export production to breeding success in seabirds. Numerous interrelated hypotheses were currently under investigation. PAL-LTER was one of 18 separate LTER programs around the globe with common research objectives, methods and scientific motivations.