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Even though compelling evidences indicate that marine microbes show biogeographic patterns, very little is known on the mechanisms driving those patterns in aquatic ecosystems. Here we examined bacterial community structure in epipelagic waters of a highly hydrodynamic area of the Southern Ocean to gain insight into the role of biogeochemical factors and water mass mixing, as a proxy for dispersal, on microbial biogeography. We targeted four water masses that converge and mix around the South Shetland Islands (northern tip of the Antarctic Peninsula). Bacterioplankton communities were water-mass specific and best explained by dispersal rather than by biogeochemical factors, which we attribute to the relatively reduced environmental gradients found in these cold and nutrient rich waters. Our results support the notion that currents and water mixing may have a considerable effect in connecting and transforming different water bodies, and consequently, in shaping communities of microorganisms. Considering the multidimensional and dynamic nature of our oceans, we recommend the analysis of water mass mixing as a more suitable approach to investigate the role of dispersal on microbial plankton biogeography rather than geographical distance. This article is protected by copyright. All rights reserved. |
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