It's amazing what a little water can do. Picture a swath of deep green in our Southwestern desert—deep green that is natural, not an Easterner's lawn. Green that doesn't consist of shrubs, trees, weeds, or grasses? Get a good wet winter and wander out to a major arroyo that most years is dry, and you might get a surprise.
As water seeps into such an arroyo, a temporary stream results, lasting
perhaps for months before the soil gives up the last of the winter precipitation. And
what appears in the new stream? Algae, photosynthetic organisms often thought to be
plants, but whose ancestry goes back far before the evolution of plants. Like plants,
though, algae use sunlight as the energy source with which to manufacture food out of
carbon dioxide and water. And as is the case with plants, other organisms in turn flock
to take advantage of this new food source. Things as far different as snails and
mosquito larvae thrive on these ephemeral resources of water and algae. Soup's on
folks, get it while you can!
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.
Algae growing in a temporary stream on the University of Texas at El Paso campus. Photograph by A.H. Harris.