The aim of this study is to understand the effect of a salinity gradient on the structure of Prokaryotic communities and nitrifying communities. Environmental controls on estuarine nitrifying communities along a salinity gradient.

Estuaries are transitional zones between marine and freshwater environments and are ideal systems to study the influence of environmental gradients on microbial biodiversity and activity. In this study, we investigated the effect of a salinity gradient on the structure of prokaryotic communities from intertidal sediments of the Douro estuary, and on the nitrification process. Four locations were chosen with distinct salinities and characterized for a range of environmental parameters, The structure of prokaryotic communities was described and ammonia-oxidizing bacteria (AOB) and archaea (AOA) were identified using16S rRNA gene.