Science Podcast: 28 June ShowTweet
Media Source: Science Magazine Podcast
Program Name: Science Podcast
Show Name: Science Podcast: 28 June Show
Broadcast Year: 2013
Original Link: http://www.sciencemag.org/content/340/6140/1595.2.full
Garcia-Pichel's work focuses on the impact of climate change on the cyanobacteria Microcoleus vaginatus and Microcoleus steenstrupii, two keystone photosynthetic microbes in the soil crust of northern (cooler) and southern (warmer) desert ecosystems, respectively. These are "pioneer" bacteria, the first to assemble and colonize desert soil, where their coverage enables areas without plant litter to resist hurricane-force winds (without coverage, dust storms would not be abated). They are photosynthetic--both carbon- and nitrogen-fixing--and the nutrients they produce through photosynthesis enriches desert water, making them a "mantle of fertility" for desert ecosystems. Without these bacteria, soil would erode and life in the desert could not be sustained. Cyanobacteria from the cooler north are already being replaced by those from the warmer south, and this will continue with the expansion of a warming, drying climate until all the northern cyanobacteria are replaced. Thanks to cultured studies, we know that southern cyanobacteria are important, but they have been studied less extensively than northern bacteria, so a scenario of only southern, warmth-loving bacteria can't be entirely mapped out. Although the studies are of U.S. desert cultures, all desert ecosystems have the same need for photosynthetic microbes in their soil crust, and therefore the replacement can be expected to happen globally as temperatures rise. These bacteria are the crux of the desert ecosystem--the direction its plant and animal life goes in a hotter, drier future will depend on the ability of microcoleus steentrupii to effectively fix carbon in the soil crust.