The waters of the Dead Sea are extremely saline, and, generally, the concentration of salt increases toward the lake's bottom. ... The deep water was saturated with sodium chloride , which precipitated to the bottom.
We have 30% (w/w) HCl this means :
100 g solution contains 30 g HCl
?? g solution contains 7.5 g HCl
By cross multiplication:
Mass of solution =

= 25 g solution
Ability to adapt to their environment?? there isn't much context to the question /: