Antarctic Ecosystems comprises 55 papers presented at the Fifth Symposium on Antarctic Biology held under the auspices of the Scientific Committee on Antarctic Research (SCAR) in Hobart, Australia, 29 August - 3 September, 1988. Both short- and long-term changes in ecosystems and community structures caused by natural and human factors were discussed to help understand the ecological processes taking place in a changing environment. The variability of ecological factors must be known for the development of realistic monitoring strategies and sound conservation practices.