Document: DWA-3-84-2

Effect of bison trampling on aquatic invertebrates in streams on Antelope Island, Utah.

MEADOWS, D.W.*

Weber State University, Ogden, UT 84408 USA ¹

Abstract:
Trampling of riparian habitats by large herbivores can have significant impacts on aquatic communities. I examined numerous environmental variables and aquatic invertebrate community composition from paired trampled and untrampled sites in eight first or second order streams on Antelope Island, in the Great Salt Lake, Utah. Percent mud and sand substrates were more common in trampled sites in most streams, while percentage cover of aquatic vegetation was lower in trampled sites. Of the twenty taxa common enough to be analyzed statistically, five showed no difference in untrampled vs trampled areas, seven had consistent differences across streams, and eight had stream x trampling level interactions. Annelid worms, ostracods, the beetle Helophorus, and the snail Physella were more common in trampled areas while the odonate Argia, the beetle Agabus, the snail Stagnicola, the dipteran Dixa, hydrophilid beetles, limnephilid caddisflies, and simulid and chironomid flies were more common in untrampled areas. These results can mostly be explained by direct trampling effects and indirect interactions of bison trampling affecting environmental features and substrate composition. These results suggest the need for mamagers and ranchers to control access of bison to riparian zones as is necessary for cows and sheep, even though bison wander more and spend much less total time in riparian zones.

Keywords: bison, aquatic invertebrates, trampling

This abstract is being presented at: 11:45 AM in session:
Oral Session #55: Invertebrates in Streams: Foodwebs.