Interhemispheric transport of viable fungi and bacteria from Africa to the Caribbean with soil dust

Studies over the past several decades have shown that aerosols (e.g., particles of pollution, dust, and smoke from fires) can be transported across great distance over the oceans, from one continent to another. There is, however, only anecdotal indirect evidence for the long-range transport (LRT) of viable microorganisms (MOs) on intercontinental scales (Brown and Hovmoller 2002). In particular, there have been no long-term systematic studies of the LRT of MOs. Here, we report on the measurements of aerosols in the trade winds on Barbados, West Indies, over a 2-year period (1996-1997). We made concurrent daily measurements of bacteria and fungi based on cultures developed from filters. Previous studies have shown that large quantities of African dust are present in winds at Barbados during much of the year. Our study shows that cultivable bacteria and fungi are only found in air that contains African dust. Air transported from other regions yields no viable organisms. These results raise questions about the factors that affect the transport and survivability of MOs in the atmosphere (Prospero et al. 2003).