Comparison of 3 Similar Headwater Streams in Central Pennsylvania During the Summers of 2015-2018

The benthic macroinvertebrate (BMI) communities of the three headwater streams, Green Gap Run, Lick Run, and Coral Run, which flow down the north slope of Penns Creek Mountain in Bald Eagle State Forest were compared through the summers of 2015 to 2018. Based on the collections from the summers of 2015-2018, Green Gap Run, Lick Run, Coral Run, were moderate replicates of each other, Lick and Coral Run being more similar, as far as the BMI communities were concerned. These streams are also similar in size and substrate composition (sand, cobble, and boulder) and maintained flow even through the drought conditions of 2016. Alkalinity averaged 195.24 (50.66- 258.10), 189.29(133.00- 230:00) and 188.95 (182.99-197.85) µeq/L during the four-year study for each of the headwater streams, respectively. They were also similar in conductance averaging 23 (17-27), 20 (19-22), and 22 (19-25) µs/cm, respectively. BMI communities were collected during the first half of July in 2015-2017 and late June of 2018 using the 6-kick method and processed by the PA DEP and US EPA protocols. The %EPT (Ephemeroptera, Plecoptera, Trichoptera) for the three headwaters ranged from 23-67% throughout the entire period. Coral run in 2016 had the lowest %EPT which may have been caused by the drought that year while Green Gap Run in 2017 had the highest at 67%. The BMI communities when compared by the Proportional Bray-Curtis Similarity method showed overlap between the three head water streams ranging from 50-59%. The range in similarity from 2015-2018 year was 33-76% overlap, which is low to high overlap. In 2018 there was the highest overlap of 76% between Coral and Lick run and the lowest overlap of 33% between Green Gap and Coral run. During this study we identified 59 families, 13 of them being added in 2018. The average Hilsenhoff metric for all three streams for the past four years was 4.29. The most dominant taxa across the three headwater steams were Crambidae and Empididae making up 22.86% of the total count combined. Our findings support that the three head water streams are very similar despite changes in weather condition from summer to summer