26 December 2006

Life from dust

A recent paper1 in Trends in Ecology and Evolution reviews some studies and discusses the transport of bacteria, fungal spores and plant pollen on dust particles by desert winds. The authors note that studies give a wide range of values for concentrations of microbes transported with dust. Also, the identities of organisms isolated from dust versus background samples vary among studies. This is not too surprising as not only the methods vary from study to study, but also the phenomenon itself, transport by the wind on dust particles, seems to be a very precarious process that is likely to produce different outcomes every time it happens.

Nevertheless, bacterial and fungal spores and plant pollen can survive the desiccating conditions in the atmosphere as well as exposure to solar UV-radiation. If they land in a suitable habitat they can start a new colony, sometimes thousands of kilometers away from their point of origin. This brings up the question of how much dust-assisted transport contributes to the biogeography of microbes, a subject that has come up before on this blog here. Along these lines, The authors ask an interesting question: "Given that most of the clay soil on carbonate Caribbean islands is derived from African dust…, is it possible to distinguish between 'African' microbes and 'Caribbean' microbes, assuming that microorganisms have been crossing the Atlantic with desert dust for centuries?" The answer must wait further studies.

The major global dust transport systems. (Figure from Kellogg & Griffi, 2006.)

There is also a brief and what seems to me a pointless discussion of the potential transport of pathogens and allergens by "dust events". We can’t stop the wind from blowing. So, deal with it and buy a mask!

1. Christina A. Kellogg and Dale W. Griffin, Aerobiology and the global transport of desert dust, Trends in Ecology & Evolution, Volume 21, Issue 11, , November 2006, Pages 638-644. Abstract

1 comment:

Duane said...

One of the best things about living here in Southern California is that there are days, primarily in the summer, when you can see what you are breathing and therefore are better able to judge when to put on your mask. I just wish those bacterial and fungal spores were a little larger so they would be easier to identify.