Effects of Brine Discharges on Benthonic Microbes

Seawater desalination facilities continuously discharge hypersaline brine (40-80 ppt) into the coastal environment. Brine waste is often denser than ambient seawater and therefore tends to sink and flow along the sea floor. We surmise that saline flow over the bottom may result in accumulation of brine within the sediment, hence alter microbial diversity, activity and growth. In this study, we examined short-term effects (2 days) of different salinities scenarios on bacteria that were found attached to the sediment. To test the impact of brine on benthonic microbes, 15 sediment cores were collected and incubated with increasing salinities ranging from 2% to 100% over the ambient levels. Our results highlight that bacterial abundance has reduced only once salinity increase by 20% above the ambient while bacterial productivity remained unchanged. The results of this study may shed new light upon the ecological impact of constant brine discharges on benthonic microbial state. We expect that in the near future we will be able to provide additional tools for management and regulation of desalination brine discharges into the coastal environment.