Bioassessment of Benthic Macroinvertebrates of the Middle Penns Creek, Pennsylvania Watershed

Abstract

During October and November 2011, an assessment of the benthic macroinvertebrate assemblage was conducted in the middle Penns Creek (PA) watershed. The survey consisted of 10 tributary sites within a 40km portion of the watershed. The goals were to establish baseline conditions for headwater streams in this section of the watershed, determine their current biotic health, and suggest possible designated use upgrades. All sample sites were low-order (1–3) streams typically of higher gradient. We calculated the Pennsylvania Benthic Macroinvertebrate Index of Biotic Integrity at each site based on the following biotic indices: Beck's Index, Total Taxa Richness, EPT (Ephemeroptera + Plecoptera + Trichoptera) Taxa Richness (Pollution Tolerance Values 0–4), Shannon Diversity Index, Hilsenhoff Biotic Index, and Percent Sensitive Individuals (Pollution Tolerance Values 0–3) . All study streams are currently designated by Pennsylvania Department of Environmental Protection (PA DEP) as Cold Water Fish (1), High Quality (6), or Exceptional Value (3) streams. We found six streams to be of highest biotic quality (IBI score >80). Benthic macroinvertebrate IBI scores for Little Poe Creek (93.2) exceeded the current designated use of High Quality by PA DEP, and should be considered for a re-designated increase to Exceptional Value. In total, 10 pollution sensitive genera (Epeorus, Leuctra, Sweltsa, Tallaperla, Acroneuria, Pteronarcys, Agapetus, Dolophilodes, Wormaldia, and Diplectrona) were present across all study streams. Panther Run (51.9) received the lowest benthic macroinvertebrate IBI score, possibly due to low total organisms which may suggest it could be experiencing ecological stressors. Our overall results indicate these Penns Creek streams to currently be of good biotic health, however long-term monitoring may be necessary to further assess anthropogenic impacts within the watershed.