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Enhanced salinities, as a proxy of seawater desalination discharges, impact coastal microbial communities of the eastern M editerranean S ea
Author(s) -
Belkin Natalia,
Rahav Eyal,
Elifantz Hila,
Kress Nurit,
BermanFrank Ilana
Publication year - 2015
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.12979
Subject(s) - salinity , mesocosm , seawater , biology , microbial population biology , ecology , productivity , oceanography , mediterranean climate , ecosystem , environmental science , bacteria , genetics , macroeconomics , economics , geology
Summary Seawater desalination plants increase local coastal salinities by discharging concentrated brine back to the sea with ∼50% higher than ambient salinities. The impacts of high salinities on microbial coastal populations of the eastern M editerranean S ea ( EMS ) were examined in two mesocosm experiments; first, during the mixed‐spring and second, during the stratified‐summer periods with average salinity of ∼39. Ambient salinities were increased by 5% and 15%. Higher salinity (15%) mesocosms induced rapid (within 2 h) declines in both primary productivity ( PP ) and algal biomass parallel to an increase in bacterial productivity. Subsequently, for the duration of the experiments (11–12 days), both C hlorophyll a and PP rates increased (2 to 5 and 1.5 to 2.5–fold, respectively) relative to unamended controls. The initial assemblages of the ambient microbial populations and intensity of salinity enrichments influenced the community responses. During the mixed‐spring experiment, the composition of prokaryotic and eukaryotic populations shifted only slightly, suggesting high functional plasticity of the initial populations. While during the stratified‐summer experiment, high salinity changed the composition and reduced the biodiversity of the microbial communities. In an ultra‐oligotrophic environment such as the EMS, salinity induced declines in microbial diversity may provide a tipping point destabilizing the local aquatic food web.