Integrity of benthic macroinvertebrate communities in Delaware Water Gap National Recreation Area: Eastern Rivers and Mountains Network 2008 summary report

Tzilkowski, Caleb; Callahan, Kristina; Marshall, Matthew; Weber, Andrew

During 2008, the Eastern Rivers and Mountains Network (ERMN) of the National Park Service (NPS) began monitoring benthic macroinvertebrate (BMI) communities in wadeable streams throughout its nine parks. There were 23 randomly selected sites and 6 (non-random) targeted sites sampled throughout Delaware Water Gap National Recreation Area (DEWA) during October 2008. In addition to BMI samples, core water quality data (i.e., temperature, dissolved oxygen, pH, and conductivity) were collected and reach-scale habitat was characterized. Thirteen sites were located on streams where boundary control points (BCPs) have been established for water quality monitoring as part of the Scenic Rivers Monitoring Program (SRMP). Core water quality parameters at DEWA sites were typical of forested watersheds with similar geologic characteristics. Relationships among core parameters were also typical – specific conductance generally decreased with decreasing pH, whereas dissolved oxygen concentrations (DO) consistently decreased with increasing water temperature. The pH of Little Flat Brook (8.66) was considerably higher than most DEWA streams, whereas pH was comparatively low (5.19) in UNT to Delaware River (Sunfish Pond). There were no exceptionally warm or cold streams throughout DEWA given the fall sampling period and DO concentrations were typically at or above saturation levels. Benthic macroinvertebrate communities throughout DEWA streams had Macroinvertebrate Biotic Integrity Index values that ranged from 26.2 (UNT to Dingmans Creek) to 65.2 (Adams Creek). Taxa richness of BMI communities ranged from 19 (UNT to Delaware River/Sunfish Pond) to 37 (Little Bushkill Creek). Density of BMI was nearly three times as great in Little Flat Brook (17,050 m-2) as in the next highest stream (Sawkill Creek, 6,254 m-2), whereas the lowest density of BMI was in Hornbecks Creek (319 m-2). Given that this report represented the first year of data collection, there were few inferences or management recommendations that could be confidently made. Biological communities (including BMI) can vary through time due to a range of naturally occurring biotic phenomena (e.g., interspecific competition, predation) and abiotic disturbances (e.g., severe drought, floods). It will take several years to determine the degree to which BMI communities naturally vary throughout DEWA and the remainder of the ERMN. Once natural variability of BMI communities is quantified, we will be in a better position to make inferences regarding the relative condition of sampled streams.

Integrity of benthic macroinvertebrate communities in Delaware Water Gap National Recreation Area: Eastern Rivers and Mountains Network 2008 summary report

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