Rier, Steven, Department of Biology -Watershed Ecology Center, Commonwealth University of Pennsylvania, 400 East Second ST, Bloomsburg, PA, 17815, firstname.lastname@example.org; Gonzales, Braedon, Department of Biology -Watershed Ecology Center, Commonwealth University of Pennsylvania, 400 East Second ST, Bloomsburg, PA, 17815, email@example.com; Martin, Hanna, Department of Biology -Watershed Ecology Center Commonwealth University of Pennsylvania 400 East Second ST Bloomsburg PA, 17815, firstname.lastname@example.org; Hurley, Mariena, Academy of Natural Sciences , Drexel University , 1900 Benjamin Franklin Parkway, Philadelphia, PA, 19103, email@example.com; Tanya, Dapkey, Academy of Natural Sciences Drexel University , 1900 Benjamin Franklin Parkway, Philadelphia, PA, 19103, firstname.lastname@example.org; Kroll, Stefanie, Academy of Natural Sciences Drexel University 1900 Benjamin Franklin Parkway Philadelphia PA¶19103, email@example.com.
Headwater streams are vital to the health and resiliency of entire watersheds. Despite their collective importance to watershed health, headwater streams are vulnerable to degradation due to their small size and lack of adequate legal protections. Therefore, understanding how human activities impair both the structure and function of these vulnerable ecosystems is essential. We combined structural and functional measures of stream periphyton (microbial growth on surfaces) in 50 headwater streams throughout the upper Delaware River Basin to determine which measures were most helpful in detecting subtle anthropogenic impacts. Structural characteristics included algal biomass, microbial N:P, diatom species composition and diversity, and the relative abundance of diatom ecological guilds. Functional measures included photosynthetic potential, measured by pulse amplitude modulated fluorimetry, and the activities of seven microbial extracellular enzymes. Environmental variables that strongly influenced both structural and functional measures were local light availability, total phosphorus, and temperature. Dissolved organic matter quantity and composition also influenced patterns in extracellular enzymes. Diatom community metrics, based on ecological traits, generally outperformed metrics based on species composition alone. Overall, combining structural and functional measures of stream periphyton gave a more complete picture of ecological conditions within each stream and how human activities have influenced the health of these systems.¶
algae , periphyton , function , assessment