Impacts of the seawater desalination plants' discharges on survival and ionic balance of Blue swimmer crab, Portunus segnis (Forskal, 1775), in the northern Persian Gulf

Nowadays, the demand for seawater desalination plants (SDPs) has risen worldwide. However, there is a lack of knowledge on the effects of discharging the SDPs brines into the Persian Gulf marine environment and its aquatics health. Therefore, this research was performed to examine the effects of SDPs brines discharged from this facility in the ecosystem of the Persian Gulf on survival and electrolytes in the Blue swimmer crab, Portunus segnis (Forskal,1775) under laboratory conditions.

Brines of two types of active SDPs in Hormozgan were collected; then,75 crabs of (P.segnis), with mean (±SD) carapace width of 9.71±2.18 cm and total weight of 61.22±1.04 g, were collected and transported to the laboratory from the Bandar Abbas coast. As a completely randomized design, the samples were tested in 5 treatments (with three repetitions). Mortality was recorded, and at the end of the experimental period (60 days),the level of some electrolytes of the hemolymph (sodium, calcium, magnesium, and potassium) was measured.

Crabs' survival percentage in treatments containing SDPs effluent decreased compared to control (86%), which was more evident in RO 100% and MED 100% treatments with 46.7% and 40%, respectively (p <0.01). The examined electrolyte levels in treatments containing SDPs brine increased compared to control, which were more significant for RO 100% and MED 100% treatments (p <0.01).

This study showed that the SDPs brines would have physiological consequences on aquatic organisms. In nature, the synergy of SDPs effluents with other sources of ecological stress will have severe impacts. Therefore, the necessary regulations and actions should be taken to minimize the environmental effects of SDPs.