Population Dynamics of an Acidic Algae in Yellowstone

One of the more striking aspects of Yellowstone National Park’s geothermal features is their color. Depending on the time of year, Yellowstone’s geysers and gurgling springs can be lined with a rainbow of vivid shades of deep red, green, and orange. These colors are the contribution of microbial communities, which are studied extensively by many of TBI’s faculty.
Especially in acidic geothermal habits, one of the visually dominant components of the microbial community are the eukaryotic algae Cyanidioschyzon, Cyanidium, and Galdieria. These microbes are sometimes colloquially referred to as the “cyanidia,” and they are the focus of one aspect of Dr. Tim McDermott’s research. Cyanidia are simple, primitive, unicellular red algae. Because of their simplicity, cyanidia can provide valuable information about the basic and essential genes involved in the lives of photosynthetic eukaryotes, including the higher plants. Consequently, there is considerable interest in studying how they tolerate the extreme features of their environmental niche, such as high temperature, the presence of heavy metal(oid)s, and extreme acidity.
Even after decades of research, including the pioneering work of Tom Brock, we still know relatively little about these mysterious organisms, which are the only photoautotrophs known to occur in hot ( ~40-57˚C (104° -135°F) and acidic (pH 0.2-4.0) environments. Historically, published data on this group of microbes has been confusing or even inaccurate. This misinformation has led to a puzzling picture of cyanidia’s ecology, physiology, and genetics. McDermott and his research group are attempting to sort out this puzzle and learn more about cyanidia. Their current efforts are centered on examining cyanidia population diversity and dynamics, especially regarding a phenomenon they call “mat decline.” In the middle of the long Yellowstone winter, cyanidia mats are dark green, appearing healthy and robust. Yet in the summer, when most of Yellowstone’s plants are flourishing, cyanidia mats appear bleached. McDermott’s data suggests that cyanidia’s seasonal mat decline is a result of a massive algae die-off which is caused, at least in part, by increased exposure to the UV irradiance which peaks during summer months.

Norris cyanidia mats

Colorful cyanidia thrive in a runoff chanel in Norris Geyser Basin