Survival skills
A human being can survive an average of three to five days without the intake of water. The issues presented by the need for water dictate that unnecessary water loss by perspiration be avoided in survival situations. The need for water increases with exercise.
Microcystin-LR
Cyanobacteria prefer to live in water bodies such as lake, ponds, reservoirs, and slow-moving streams. When the water is warm there are enough nutrients available for the bacteria to survive. Most cyanobacteria produce toxins, of which microcystin is only one group. When a cyanobacterium dies, its cell wall degrades while the toxins are released in the water. Microcystins are extremely stable in water and withstand chemical breakdown such as hydrolysis or oxidation. The half-life of this toxin is 3 weeks at pH 1 and 40 °C. At typical conditions in the environment, however, the half-life is 10 weeks.