Rapid Bioassesment of Cobleskill Creek Prior to Stream Restoration Efforts: Establishing a Reference Reach to Monitor the Recovery of the Stream Biotic Integrity

Abstract

In early fall 2011 Cobleskill Creek and its associated tributaries were severely impacted by Hurricane Irene and Tropical Storm Lee, causing record levels of flooding across New York State. A 500-meter section of Cobleskill Creek adjacent to the SUNY Cobleskill campus, in Scoharie Co. experienced widening of the channel caused by floodwaters, resulting in elimination of the riparian buffers and eroding banks creating the potential for nutrient run off. With funding from the Natural Resource Conservation Service (NRCS), a channelization project is slated to begin in the spring of 2016. This project will establish a central channel in this 500m section of the stream and provide for the implementation of riparian buffers. Rapid Bioassessment was conducted at 2 locations; upstream and downstream of the restoration site on Cobleskill Creek. We measured a 100-meter stretch at both locations and characterized the physical parameters of each site such as stream flow, velocity, and width. Macroinvertebrates were sampled from the upstream and downstream sites, on five different dates, using Surber sampler technique prescribed by Environmental Protection Agency (EPA) Rapid Bioassessment technique protocol. A 100-individual sub sample was taken at the end of each sampling event. Subsamples were identified to the family level, enumerated and analyzed. Indices of diversity and biotic integrity were applied to samples from both sites for comparison. Student's t-tests concluded that there were no differences between the upstream and downstream sites in Shannon's diversity index (P-value 0.26 α=0.05), Simpsons diversity index (P-value 0.54, α=0.05) or evenness (Modified Hill's Ratio) (P-value 0.22, α=0.05). Lastly the Hillsenhoffs biotic index showed no significant difference between the two sites (P-value 0.65, α=0.05). The similarity between the upstream and downstream sites indicates that the upstream site will serve as a viable reference reach to monitor the recovery of the biotic integrity of Cobleskill Creek following the ecological restoration event.