Temperature Drives the Continental-Scale Distribution of Key Microbes in Topsoil Communities

by Elizabeth Medford

While it has become fairly well known that global warming will cause plant and animal species to migrate toward cooler areas or cause range loses, until now it has been unclear whether this will also be true for microorganisms. Microorganisms play a key role in soil fertility and erodibility making this study relevant both for future agricultural endeavors as well as future efforts relating to ecological protection. Garcia-Pitchel et al. (2013) conducted continental-scale compositional surveys of soil crust microbial communities in the arid regions of North America. The results from these surveys imply that temperature caused latitudinal replacement between two key topsoil cyanobacteria. The cyanobacteria Microcoleus vaginatus behaved more psychrotolerant and less thermotolerant while M. steenstrupii behaved more thermotolerant. These results imply that the later may replace the former as temperature increases globally. Further studies are required to fully understand the impact of this microbial replacement. Continue reading

Fertilizing the Ocean to Trap CO2

by Emil Morhardt

One of the ways scientists have hoped to suck CO2 out of the atmosphere is by adding nutrients to the ocean that are limiting the growth of photosynthetic phytoplankton. The idea is that with the proper nutrients (iron being the main one experimented with so far) the plankton would capture CO2 photosynthetically, convert it to biomass, die, then sink to the ocean floor, “exporting” the new carbon in their bodies to a place where it couldn’t have any effect on global warming. There are a number of posts in this blog dealing with those experiments under the category “Ocean Fertilization”; they haven’t worked very well because, among other things, instead of sinking to seafloor, the phytoplankton get eaten by zooplankton which metabolically convert them back into energy and CO2 which can then diffuse back to the atmosphere, or at least contribute to ocean acidification.

A fascinating paper just published in Science, examines the nutrients limiting the growth of the photosynthetic marine cyanobacterium, Prochlorococcus, in a much more interesting and comprehensive way than previously possible, and although it doesn’t directly speak to the feasibility of fertilizing the ocean to trap CO2 (sorry about the somewhat misleading title to this post) it greatly increases the potential sophistication with which such a goal could be pursued. Continue reading