- Historic Sites
A Heritage In Peril
In a mere three hundred years we have despoiled a rich continent and seriously disturbed its balance of life. Nature may not let us escape the consequences much longer
August 1966 | Volume 17, Issue 5
A decade was needed to prove that the widespread use of chemical sprays had a crippling effect on the reproductive systems of fish, too. In 1956 and 1957, every one of the young trout hatched at the Lake George Fish Hatchery in New York’s Adirondack Mountains died. The eggs had been collected from a watershed that had been plied with DDT for the control of gypsy moths, blackflies, and mosquitoes. Small fish were concentrating the chemical and passing it on to the female lake trout, which in turn were destroying their own progeny by passing it into the stored fatty material of their eggs.
On the lower Mississippi River, a delayed reaction to another pesticide, endrin, precipitated the deaths of three and a half million fish in 1960, a quarter of a million more in each of the two succeeding years, and a staggering 5,175,000 in the winter of 1963-64. For the first time, in every major waterway, more fish were being killed by pesticides than by all other causes combined—sewage, soaps and synthetic detergents, oil, tar, and the leakage of sulfuric acid from mines.
The concentration of the poison does not have to be very large to be lethal. On the lower Mississippi, for instance, there was only 0.054 to 0.134 parts of endrin per billion of water. The victims, mostly catfish, had picked up contaminated silt particles while feeding on the river bottom. They had concentrated amounts as high as 6.0 parts per million in their fatty tissues during the summer; then, as water temperatures dropped in winter, and the fish were feeding less, they absorbed these fatty reserves into their bloodstreams, and with them lethal levels of endrin. In the estuaries,too, the larvae of shrimp were demonstrating a low tolerance to endrin, yet a great ability to concentrate it from mere traces in the water. More than fish were affected. The bayous and backwaters of Louisiana lost countless numbers of turtles, crabs, alligators, and otters, along with cormorants and other waterfowl; to this day the brown pelican, the official state bird, has not returned in any numbers to breed along the coast.
Concerned about the health of the people of the bayous, who subsisted on catfish; about the commercial sale of possibly contaminated fish and shrimp; and about the pollution of drinking water in the city of New Orleans, the United States Public Health Service set up monitoring stations and traced one third of the endrin in the Mississippi to a plant producing the chemical in Memphis, Tennessee, 450 miles upstream. The company was enjoined to clean up a dump which Senator Abraham Ribicoff of Connecticut called a “primitive and dangerous nuisance"; over the past two winters there have been no more catastrophic fish kills. Heavy agricultural use of chemicals on fields of cotton and sugar cane continues in the delta, however, and the runoff into the river has created pockets of prolific, insecticide-resistant mosquito fish, golden shiners, bluegills, green sunfish, and cricket frogs. Here are the beginnings of supercontaminated food chains.
Recently, as the awareness of such dangers has increased, we have begun taking remedial action. In 1964, the Interior Department virtually banned the use of DDT, endrin, and other chlorinated hydrocarbons on all lands it controls. The Dingell-Neuberger Bill, passed by the Eighty-ninth Congress, has increased federal funds for probing the effects of chemicals on wildlife—from a former ceiling of $2,565,000 a year to $3.2 million this year and $5 million in each of the next two years. And attempts are being made to rebuild environments shattered by the careless use of pesticides. Neighboring Canada and our own state of California are taking the lead in experimenting with integrated chemical and biological controls. An example is their use to control aphids, the most prolific of insect pests, in the alfalfa fields of California. Small amounts of Systox (a nonresidual organic phosphate) in the juices of the plants kill only the sucking insects, leaving the predator population healthy. Other enemies, such as parasites and fungi, are then imported to attack the aphids. The result is an artificial balance, maintained without excessive cost, great toxic hazard, or the risk of increasing the pests’ resistance to insecticides.
So, in great ways and little, the battle to save whatever is left of our wildlife heritage goes on. As this is written, the major skirmishes are proposals for the North Cascades and Redwood national parks in the Northwest, which are opposed by mining and logging companies; the “wild rivers” bill, which would preserve “free-flowing stretches of our great scenic rivers” from exploitation; and the controversy engendered by the man-made drought in the Everglades, where a system of locks built by Florida flood control authorities and the Army’s Corps of Engineers has cut off all but a trickle of the normal flow of water from Lake Okeechobee into the Everglades National Park, posing a crucial danger to its wildlife. (In February of this year the Corps announced that the old Miami Canal would be cleared out and extended, but federal funds are still being sought to pay for pumping.)