Do microscale flows drive diatom community strucuture?
Each spring, large mats of the filamentous macroalgae Cladophora glomerata emerge in the Eel River in the Angelo Coast Range Reserve, a research facility in the University of California’s Natural Reserve System. Over the course of the summer, the mats change color —from green to yellow to rusty brown—as the algal filaments become covered, first with non-nitrogen fixing diatoms, then with thick layers of epiphytic diatoms containing nitrogen-fixing endosymbionts. Amy Hansen, a PhD student working with Miki Hondzo and Jacques Finlay, began to wonder what drives the change in diatom community structure, and therefore color, on the Cladophora filaments. The Eel River is a nitrogen limited ecosystem, and Hansen and her advisors speculate that constrained water flow within dense algal stands will lead to low local concentrations of dissolved inorganic nitrogen and that water within the nooks and crannies of the rough epiphytic coating will be stagnant. Hansen hypothesizes that under those co
