PT - JOURNAL ARTICLE AU - Sergio E. Morales AU - Moana Meyer AU - Kim Currie AU - Federico Baltar TI - Are oceanic fronts ecotones? Seasonal changes along the Subtropical Front show fronts as bacterioplankton transition zones but not diversity hotspots AID - 10.1101/109868 DP - 2017 Jan 01 TA - bioRxiv PG - 109868 4099 - http://biorxiv.org/content/early/2017/02/20/109868.short 4100 - http://biorxiv.org/content/early/2017/02/20/109868.full AB - Ecotones are regarded as diversity hotspots in terrestrial systems, but it is unknown if this “ecotone effect” occurs in the marine environment. Oceanic fronts are widespread mesoscale features, present in the boundary between different water masses, and are arguably the best potential examples of ecotones in the ocean. Here we performed the first seasonal study along an oceanic front, combining 16S rRNA gene sequencing coupled with a high spatial resolution analysis of the physical properties of the water masses. Using the Subtropical Frontal Zone off New Zealand we demonstrate that fronts delimit shifts in bacterioplankton community composition between water masses, but that the strength of this effect is seasonally dependent. While creating a transition zone where physicochemical parameters and bacterioplankton communities get mixed, this ecotone does not result in increased diversity. Thus unlike terrestrial ecotones, oceanic ecotones like fronts are boundaries but not hotspot of bacterioplankton diversity in the ocean.