Green and Orange stream algaeThe most abundant life we see in the Dry Valleys is the stream algae. They come in a few different colors: orange, red, green and black. All of these live in and around the streams and each color has a different niche. For example, black algae look sort of like mosses and grow in the wetted zone next to the stream, while orange algae like to grow in mats on top of rocks in the stream bed. A really neat thing about the algae is that over winter when the streams dry up, they enter a biological state called anyhdrobiosis. Basically this is like freeze drying. Their tissues dry up and shrivel, but soon after they are exposed to water again they resume normal functioning. Studies have shown that the re-hydration process can happen fully within a few hours. The algal mats are made up of various single-celled and colonial organisms, mostly cyanobacteria (prokaryotic “blue-green” algae) and diatoms (silica-walled eukaryotes). My fellow stream team member Lee is doing her PhD project on the algae and trying to develop a technique to more easily identify the diatoms using their DNA and RNA.
4 comments:
What provides the sustenance for the algae? Are they photosynthetic organisms?
They are indeed photosynthetic organisms, but also use nutrients in the stream water to thrive. In the wetted zone (or hyporehic zone) on the stream edge, weathering of rocks and mobilization of other nutrients (like nitrate, phosphate, etc) takes place. Stream water exchange with the hyporehic zone water makes these nutrients available to in-stream algae.
Sounds like Stone Soup to me.
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