The journey of marine microbes

By collecting water samples up to six kilometres below the surface of the Southern Ocean, UNSW researchers have shown the impact of ocean currents on the distribution and abundance of marine microorganisms.

Twenty five samples were collected across a 3000 kilometre stretch of ocean between Antarctica and the southern tip of Western Australia. Sampling depths were determined by temperature, salinity and dissolved oxygen measurements, to ensure microbes were collected from all the distinct water masses of the Southern Ocean.

These water masses include the circumpolar deep water, which flows toward the south pole from the Indian, Pacific Ocean and Atlantic oceans; the surface water near the Antarctic coastline; and the cold, dense Antarctic bottom water, which flows north, away from the pole, at more than 4 kilometres depth.

Genetic sequencing of the microbial DNA in each sample was carried out to characterise the microbial communities in different water-masses. The research shows that communities that are connected by ocean currents are more similar to each other.

For more details, see the following paper:

David Wilkins, Erik van Sebille, Stephen R. Rintoul, Federico M. Lauro, Ricardo Cavicchioli. Advection shapes Southern Ocean microbial assemblages independent of distance and environment effects. Nature Communications, 2013; 4 DOI: 10.1038/ncomms3457

Posted by Tim Sandle