Environmental Impact Assessment of Brine Discharge from Desalination Facilities via Bioindicators

This study investigates the environmental impacts of brine discharge on the biota. Physicochemical parameters, including faunal composition, percentage cover, abundance and biodiversity, were assessed. Seawater temperature, pH and turbidity showed a spatial variation and recorded the highest at the mixing zone (Z3). Salinity, total dissolved solids (TDS) and conductivity showed seasonal and spatial fluctuations and were the highest at the discharge zone (Z2) and showed lower values at the standard zone (Z1) throughout both seasons. This study recorded a total of 48 species, comprising 251 individuals. Among these, 24 were fish species (50%), and 13 belonged to the phylum Cnidaria (27.08%), including 7 species of soft corals and 6 species of Madriporaria (stony corals). Mollusca represented by 5 species (10.42%) dominated by Gastropoda (4 species) and only one species of Bivalvia. Echinodermata and Porifera were represented by only 3 species (6.25%) for each. Notably, it was observed that 13 species were completely absent in winter, compared to only 3 species that were not recorded in summer. The non-living sand-muddy substrate components were dominant at all studied zones. Seagrass meadows of Halophila stipulacea were found only in the standard area (Z1), located north of the discharge pipe, covering 26% of the substrate. These seagrasses meadows were completely absent in the other zones during the study period. The live corals were observed only at Z1 and Z3 as scattered, very small colonies. The percentage of dead corals was higher in Z3 than in Z1 (3 and 1%), respectively. Shannon -Wiener diversity index recorded its lowest (3.02) in winter and highest (3.13) in summer with an average of 3.07. In conclusion, this study shows that the brine discharged from desalination plants has adverse effects on marine biota.