Low relief mat covers boulders and sediment in swiftly flowing water. Darker spots are areas with higher diatom abundance. Dark color indicates abundant diatoms within the blue-green algal felt. At somewhat slower flow vertical pinnacles form. These are buoyed by gas bubbles, but also firm enough to stand up without being buoyed.
Darker colors indicate increased diatom abundance.
Abundant pinnacles of blue-green algae and diatoms in calmer water. Gas bubbles provide buoyancy. Close-up of green algal bottom cover. Detail view of algal filaments. The large cell size indicates that it is a green algae, and the spiraling chloroplast indicates a species of Spirogyra .