Phytoplankton and bacterial communities dynamics along the salinity gradients in the Seomjin river estuary

Abstract

We estimated the phytoplankton and bacterial community dynamics along the salinity gradients in the Seomjin River estuary, by investigating the seasonal abiotic and biotic factors at 14 sites at high and low tide during the spring tide season. We performed bioassays to identify the effect of additional nutrients (+N, +P, +NP) on phytoplankton growth and performed high-resolution 16S rRNA tag pyrosequencing to obtain snapshots of the bacterial diversity and community structure along the salinity gradients in spring and autumn. The algal bioassays and the field surveys indicated that nitrogen and phosphates could be limiting factors in the saltwater and freshwater zones in the Seomjin River estuary. The Bacterial diversity was very high at Station 9, where freshwater and saltwater species were mixed. Our study demonstrated dynamic changes in the phytoplankton and bacterial communities along tidal levels and salinity gradients.on. We performed bioassays to identify the effect of additional nutrients (+N, +P, +NP) on phytoplankton growth and performed high-resolution 16S rRNA tag pyrosequencing to obtain snapshots of the bacterial diversity and community structure along the salinity gradients in spring and autumn. The algal bioassays and the field surveys indicated that nitrogen and phosphates could be limiting factors in the saltwater and freshwater zones in the Seomjin River estuary. The Bacterial diversity was very high at Station 9, where freshwater and saltwater species were mixed. Our study demonstrated dynamic changes in the phytoplankton and bacterial communities along tidal levels and salinity gradients.