THE FAUNA OF NORTH-AMERICAN TEMPERATE COLD SPRINGS - PATTERNS AND HYPOTHESES

1. The relative abundance of six classes of macroinvertebrates in fifteen mid-Appalachian and thirteen other North American cold springs is briefly reviewed. In both surveys peracaridans, molluscs, and triclads dominated the hard-water limestone springs, whereas insects dominated the relatively acidic soft-water springs. 2. A hypothetical framework is offered to explain the dominance of non-insect taxa in hard-water limestone springs. The importance of a non-emergent lifestyle and high population densities in springs is emphasized. Some evidence is offered in support of the proposed hypotheses, but most of the testing remains to be done.