Other effects of warfare on the undersea world are: (a) [Undersea explosions] These take a serious toll on marine animals, especially ray-finned bony fish, which comprise about 95% of the fish in the sea. The air bladders of these fish are easily ruptured by underwater explosions. In addition, some of the materials used in explosives are poisonous. (b) [Oil] A threat is posed by the enormous increases in tanker size since the 1940s, and the emplacement of vulnerable offshore oil platforms around the world: oil contamination of the sea could be significant in a major war. (c) [Herbicides] As a result of massive herbicide spraying of mangrove forests along the coast of South Vietnam during the Vietnam War, coastal habitats were devastated. Scientists surveying offshore areas found that the loss of these marine nurseries and breeding grounds had caused a severe decline in the populations of fish, planktonic organisms, and shellfish. Recovery, they estimated, could take more than a hundred years. (d) [Testing of nuclear weapons] Since the 1940s these have been associated directly with the sea. More than 1,000 nuclear bombs have been detonated; of these, 373 were exploded in the atmosphere (about 80% of the long lived components of these blasts probably reached the sea), 35 were exploded along the sea surface, and 6 were detonated undersea.
If a major nuclear war erupts, the instruments of greatest violence will probably emerge from the sea. The effects of wartime nuclear contamination in the sea could be devastating. Long-lived radioactive products would be distributed by ocean currents throughout the sea. Several of such products are taken up by marine organisms and distributed through the food web, especially strontium-90 (which follows the same course in organisms as calcium) and caesium-137 (which acts like potassium). Plutonium is also taken up by many marine organisms, some of which concentrate it to levels from a thousand to as much as ten thousand times higher than its initial concentration in seawater.