Amateur Naturalist: Springs And Crusty Lichen

Iron bacteria growing in a small drainage pool. Photo by Robert Dryja
 
By Robert Dryja
Los Alamos
 
The natural and urban worlds exist in close proximity to one another in Los Alamos. Finger-shaped mesa tops are separated by canyons. Urban Los Alamos is built on the mesa tops. The canyons in contrast are filled largely with forest toward their mountain origins. The canyons would be considered to be large parks or preserves in other parts of the country. An initial impression is that the canyons still are mostly in a natural state after nearly seventy years of urban development on the mesa tops.
 
However a variety of urban influences can be found in the natural appearing canyons. Acid canyon provides examples of these influences. One example is the Ranch School trail. It was made in the 1920’s by the boys from the Ranch School. It extends the length of the canyon until it merges with Pueblo canyon. The Ranch School boys chiseled the rock walls at several sections adjacent to the trail. The trail surface was made level with the careful placement of carved stone. 
 
Two more subtle examples can be seen at the end of Acid canyon where it merges with Pueblo canyon. The first subtle example involves a permanent spring. Its water is clear. Thread-like green or brown algae grow in it. Even though the air temperature may be at freezing in winter, a thermometer shows that the water is at 39 degrees, well above freezing.   
 
An unusual small pool occurs along the side of the stream coming from the spring. The pool is only about two feet across but its water has a distinctly brownish-orange color. Careful observation shows that the water in this pool is about one inch higher than the water in the stream. It slowly drains into the adjacent stream. A check with a thermometer shows that the pool temperature is 45 degrees rather than 39 degrees. This small pool evidently is part of a separate spring that emerges close to the stream.
 
A different sort of thread algae appears to be living in the warmer water of the pool. However it is iron bacteria rather than algae. The iron bacteria obtain their energy from a reaction with ferrous iron – rust — instead of photosynthesis with light. A brownish-orange, gelatinous and stringy slime is the result. But where is the iron coming from to feed the bacteria?  
 
Perhaps a nearby pipe that comes down one side of the canyon and then back up the other side is providing the ferrous iron. It was constructed years ago and is rusting. The impact of urban development is immediately obvious with the example of the iron pipe. The impact is less obvious with the growth iron bacteria in a small pool.
 
What looks like another not so subtle urban influence occurs a short distance away at the intersection with Pueblo Canyon. Boulders appear that look as if someone had been randomly painting them white. But why would someone crudely paint a few boulders at the bottom of a canyon in a forest? A closer look shows that there is a crusty-like material on the boulders rather than paint. The material can be picked off the boulders. The crusty-like material actually is a species of lichen. 
 
Crusty lichen grows in a variety of settings, the same as other lichen species. However crusty lichen can tolerate a level of air pollution that other species of lichen cannot. Other species for example cannot grow in even the slight presence of sulfur dioxide gas. Only crusty lichen is immediately apparent over a distance of about fifty feet up or down stream from the rocks on which it is growing. An exploration for various kinds of lichens throughout the area would help clarify if indeed only crusty lichen is present. Perhaps the crusty lichen is indicating some low level pollutant is slowly working its way down Pueblo canyon from the old sewerage plant or from some other source.     
   
The canyon bottoms provide pathways for wild life and the water in the springs attracts them. An occasional bear therefore may come by while you are pondering the ways of iron bacteria and crusty lichen. The bear is a reminder that the canyons still are predominately natural areas even if urban influences are present.
 
Exploring down the Rabbit Hole —Learning more like Alice
 
Learn about iron bacteria at: http://www.fosc.org/PDF/IronBacteria2.pdf
 
Learn some history about lichens and air pollution at: https://www.anbg.gov.au/lichen/ecology-polution.html
 
Learn about research on lichens at: http://gis.nacse.org/lichenair/index.php
 
Crusty lichen growing near the intersection of Acid and Pueblo Canyons. Photo by Robert Dryja
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