WHEN visitors to King Herod’s mountaintop palace at Masada looked out over the Dead Sea, what would have fascinated them most? The dramatic views, the legend that the evil city of Sodom lay beneath the water below, or the fact that in the sweltering heat of the summer, the water often took on a strange red hue?

Herod could not have known, but the water’s recurrent blush was due to blooms of microorganisms that have evolved special mechanisms for living in this most inhospitable environment. According to Aharon Oren, a microbiologist at the Hebrew University of Jerusalem who specialises in Dead Sea life, these organisms not only manage to survive in the Dead Sea’s salt-saturated chemical soup-they can’t do without it.

Like many organisms, the Dead Sea’s life forms have had to put up with changes to their environment over the past century that have made it harder for them to survive. Since the 1960s, Israel has diverted much of the flow of the River Jordan, the main source of the sea’s freshwater. Together with climatic changes that began earlier in the century, this has shrunk the sea and made it ever saltier. It has also altered the delicate density-based stratification of its waters on which the algae and bacteria depend. During the past 15 years they have bloomed only sporadically.

In the wake of its 1994 peace agreement with Israel, Jordan is pressing for a revival of plans to link the Dead Sea with the Red Sea (“Raising the Dead Sea”, New Scientist, 22 July 1995, p 32). There has long been talk of such a link, and of…