Low diversity of planktonic bacteria in the tropical ocean.

摘要: The diversity of macro-organisms increases towards the equator, with almost no exceptions. It is most conserved biogeographical pattern on earth and thought to be related increase temperature productivity in tropics. extent orientation a latitudinal gradient marine bacterioplankton controversial. Here we studied euphotic zone Atlantic Ocean based transect covering ~12.000 km from 51°S 47 °N. Water samples were collected at 26 stations five depths between 20 200 m sequentially filtered through 8 μm, 3 μm 0,22 μm filters, resulting total 359 samples. Illumina sequencing V5–V6 region 16S rRNA gene revealed clear biogeographic double inverted gradient. Diversity was higher mid-latitudinal regions decreased equator. This for bacteria all three planktonic size fractions. showed non-linear relationship negatively correlated bacterial cell numbers upper depth layers (<100 m). gradients mechanisms that govern them are distinct those found macro-organisms.