ARE MACROINVERTEBRATE ASSEMBLAGES IN MID-APPALACHIAN SPRINGS USEFUL SIGNALS OF GROUNDWATER SUSTAINABILITY OR GEOCHEMISTRY?

This poster focuses on one component of a larger project designed to test whether various chemical, microbial and (or) biological factors at spring sources represent useful signals of groundwater-flow sustainability. Here we compare the relative abundance of various macroinvertebrates at the sources of nine springs in karst landscapes of Pennsylvania and West Virginia (USA). We predicted that springs with long source-flow paths (and presumably more persistent flow) should harbor macroinvertebrate assemblages with higher total abundance and greater percentages of crustaceans and other totally aquatic, non-insect taxa, compared to those with more shallow (less persistent) flow. This prediction is partially borne out in comparisons of two pairs of geographically proximate springs that have been interpreted as being dominated by deep (D) versus shallow (S) flow: Warm Spring (D) and Cold Spring (S) in Huntingdon County, PA; and Berkeley Spring (D) and Cacapon State Park Spring (S) in Morgan County, WV. In both pairs, the springs with deeper flow have larger numbers of macroinvertebrates and relatively more crustaceans (amphipods and isopods). However, these comparisons are complicated by significantly higher water temperatures in the D versus S springs, and marked differences in water chemistry (e.g. pH, calcium content and alkalinity) between Warm and Cold springs. Comparisons of all nine study springs (along with literature data) suggest that geochemistry (especially concentrations of calcium and dissolved oxygen) and other local environmental factors have significant impacts on the macroinvertebrate assemblages observed. Therefore, the usefulness of macroinvertebrate assemblages in springs as a signal of groundwater-flow depth and sustainability remains an open question.