BIOLOGICAL INVASIONS OF FRESH-WATER - EMPIRICAL RULES AND ASSEMBLY THEORY

Because the integrity of aquatic ecosystems is being challenged worldw ide by invading species, there is a growing need to understand the inv asion process and to predict the success and effects of invading speci es. Case histories of fish invasions in streams, lakes, and estuaries indicate that invading species and systems being invaded interact in i diosyncratic ways that are often hard to predict, largely because of t he role of environmental variability in deter mining rite outcomes of invasions. We nevertheless present a conceptual model of aquatic invas ions and a dozen empirically-derived rules that seem to govern most aq uatic invasions. While these rules are limited in their usefulness, th ey do seem to have more predictive value than rules derived from commu nity assembly theory. Copyright (C) 1996 Elsevier Science Limited