AIMS_SE_Approach2_PaintRock_EEAS

This study was conducted in the Paint Rock watershed (outlet: 34.9686, -86.1650) which lies on private land in Jackson County, AL, near Estillfork. It drains a non-perennial tributary to Burks Creek and spans 2.97 km² of deciduous forest in the Cumberland Plateau. Elevation ranges from 211 to 550 m, and the watershed feeds into the Paint Rock River (Tennessee basin). The climate is humid subtropical, with mean January and July temperatures of 4.4°C and 25.4°C, and annual precipitation of 1,390 mm. This watershed was included in a seasonal sampling survey (AIMS Approach 2) conducted from January 2022 to January 2024 as part of the Aquatic Intermittency effects on Microbiomes in Streams (AIMS) Project. The field team collected data on hydrology, biogeochemistry, and microbial ecology at 7 sites within each watershed. Site selection balanced three priorities: (1) targeting locations with existing long-term monitoring infrastructure; (2) including sites near springs and tributary confluences; and (3) capturing variability in drainage area and topographic wetness index (TWI), which are linked to flow permanence. At each site, samples of water (when present), biofilm, leaf litter, and sediment were collected. Microbial enzyme activities were measured to assess organic matter decomposition (β-glucosidase, phenol oxidase, peroxidase) and nutrient mineralization (N-acetylglucosaminidase for nitrogen, phosphatase for phosphorus). Enzyme activities were quantified using fluorometric methods with 4-methylumbelliferyl (MUB) substrates or colorimetric methods using 4-nitrophenyl (pNP) and L-DOPA substrates.