The heavily populated Israeli coastline is under constant anthropogenic changes due to discharge of industrial effluents, activated sewage sludge, cooling water from power plants, overfishing etc. Additionally, since 2005, the installation of large plants of seawater desalination by reverse osmosis (SWRO) also resulted in the concurrent discharge of brines and chemicals used in the process to the coastal areas. Seawater desalination was introduced as an urgent solution to the country’s freshwater shortage, and currently provides roughly 390 million m3 (Mm3) y-1 of fresh water. The forecasts are that by 2025 water production will reach 750 Mm3 y-1, ~30% of Israel’s freshwater supply via 5-7 large-scale plants.
Salinity gradients created near desalination plant outfalls are characteristic along the coastal environment. Understanding microbial adaptation to increasing salinity at the community level is crucial to predicting how the biogeochemistry of coastal aquatic habitats will change over space and time. In an on-going study, we present the first results on community structure and physiological responses of planktonic microbial communities to salinity changes similar to changes caused by desalination industry brine discharges near disposal outfalls. Our results show that under the experimental conditions, the natural communities were able to maintain balanced growth over the salinity range with apparent changes in community structure and physiology. Adaptation to salinity fluctuations is crucial for planktonic organisms living in a coastal constantly changing environment, and acts as a decisive factor for the community functional properties.