Assessing the risk of exotic Collembola invading subantarctic islands: prioritising quarantine managementProceedings of the Xth international Colloquium on Apterygota, České Budějovice 2000: Apterygota at the Beginning of the Third Millennium

Abstract

Summary Alien invertebrates pose considerable threats to subantarctic island ecosystems and, with warming climates, because the likelihood of immigrants establishing breeding populations on these islands, is increasing. These species can have profound effects on ecosystem structure and function and are capable of influencing landscape values. An assessment protocol has been designed to allow prioritisation of the risk of alien invasion. The protocol is tested for Heard Island using Collembola. Twenty species already present on other subantarctic islands were chosen as candidate taxa. They were scored from 1 to 5 according to five criteria, namely distribution, life history, habitat, ecosystem synchrony and dispersal ability. They can be considered to represent: 1. proximity potential, 2. population potential, 3. establishment potential, 4. persistence potential and 5. spread potential, respectively. The scores are summed to give a total invasion risk potential, so that species can be ranked in order of probability of introduction to Heard Island. The highest ranked species include members of the family Hypogastruridae, already recorded from South Georgia and the Antarctic Peninsula, and certain soil-dwelling, parthenogenetic Isotomidae. Appropriate management strategies are proposed to reduce the risk of the high priority species being introduced to Heard Island.