Response of stream filamentous algae and benthic periphyton to wildfire ash

Wildfires are novel aridland disturbances due to human activity, invasive grasses, and excessive wet seasons. Sycamore Creek, an intermittent stream in central Arizona, has recently experienced two large fires. Ash is transported during rain storms and influences stream ecosystems by decreasing dissolved oxygen and increasing dissolved organic carbon, organic nitrogen, and inorganic nitrogen. In streams, algae in filaments and periphyton are responsible for most primary production and play an important role in nitrogen and carbon cycling. The nitrogen input from ash is expected to enrich algal biomass growth with increased concentrations of ash exposure. Ash was collected in the mid-reaches of Sycamore Creek, then analyzed for carbon and nitrogen composition. A leachate was created by shaking one part ash with three, five, or ten parts Nanopure water for one hour and letting it sit for 48 hours before removing particles with a 0.45 μm syringe filter. Due to a lack of water in Sycamore Creek, filamentous algae are collected from aridland Rye Creek. Periphyton in Rye Creek is scraped from benthic rock sediment and homogenized in a slurry with Nanopure. 40 glass mesocosms are filled with 200 mL of Nanopure water, 1:3 leachate (10), 1:5 leachate (10), or 1:10 leachate (10). Five mesocosms of each group have 10 grams dry weight of filamentous algae and five mesocosms have 20 mL of periphyton slurry. The mesocosms are placed for one week in a photoperiod and temperature controlled room. Algal biomass is measured as chlorophyll α and ash-free dry mass.

Presentation Preference: Poster

Primary Presenter: Carly Steckling, Arizona State University (steckcar21@gmail.com)

Authors:

Carly Steckling, Arizona State University  (csteckli@asu.edu)

Edauri Navarro Pérez, Arizona State University  (enavar14@asu.edu)

Nancy Grimm, Arizona State University  (nbgrimm@asu.edu)