Date of Award


Document Type


Degree Name

Master of Science (MS)



First Advisor

William M. Brenneman Ph.D.

Second Advisor

Jeffery Larkin Ph.D.

Third Advisor

Holly J. Travis D. Ed.


The importance of macroinvertebrates in stream ecosystems is well known as these animals serve a variety of functions. Many studies have shown that they occupy leaf packs (collection of detritus in streams). Most studies use artificial leaf packs or detritus traps. This study examines total density, generic richness and feeding group densities of macroinvertebrate occupancy in leaf packs seasonally. Samples were collected from naturally occurring leaf packs found in 2 Western Pennsylvanian headwater streams. Total density of macroinvertebrate occupants of the leaf packs were shown to vary seasonally. The shredder feeding group was shown to have higher density in the summer season. Trends of higher density and generic richness were evident as the temperature difference between stream and leaf pack increased. This study shows the viability of sampling natural leaf packs. It also shows that numbers of macroinvertebrates in leaf packs change seasonally and points to temperature difference between stream and leaf pack being an important factor in macroinvertebrate occupancy of leaf packs.