Consequences of a Sea-Level Canal

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Little is known of the possible ecological consequences of a sea-level canal across the isthmus connecting North and South America, and engineers tend to believe that because there is no evidence of possible ecological harm, none would ensue. The recent report of the Atlantic-Pacific Interoceanic Canal Study Commission (SN: 12/12, p. 445) devotes four pages to environmental questions and tends to pooh-pooh any possible dangers. Ecologists are not nearly so sanguine. They point out the reason there is no evidence of possible harm is that studies have not been done. Dr. Howard L. Sanders of the Woods Hole Oceanographic Institution, Woods Hole, Mass., is disturbed about apparent discrepancies in emphasis between the commission report and findings of a National Academy of Sciences committee on the canal (SN: 4/ 11, p. 364). There are thousands of possibilities of mixing of similar species from Atlantic and Pacific sides, he says. The results, he adds, are unpredictable and could be serious. Dr. Sanders and others, therefore, urge that if a canal is to be dug a foolproof-as-possible biological lockpreferably of heated fresh water-be incorporated and that the most thorough studies possible be done prior to construction. Although there has been little research to date on the ecological effects of the proposed canal, Drs. Ira Rubinoff and Chaim N. Kropach of the Smithsonian Tropical Research Institute in Balboa, Canal Zone, recently completed a study of Pelamis platurus, the highly venomous black and yellow sea snake that now inhabits the eastern Pacific (SN: 12/5/68, p. 579). They conclude that if the sea snake got into the Atlantic, it would at first be attacked by Atlantic predators. But then these predators would evolve avoidance mechanisms and the snake would spread throughout the Caribbean. Such an event could be disastrous to the tourist industry, says Dr. Sanders. Even if the sluggish and fairly nonaggressive snake did not attack humansit generally does not in the Pacific-its psychological effect could be formidable. Drs. Rubinoff and Kropach reported on their work in the Dec. 26 NATURE. The two researchers used tanks to expose the snakes to predators from the Atlantic and Pacific sides. The Pacific predators served as controls to measure how the behavior of the Atlantic predators, even though sometimes of the same species as the Pacific ones, differed. The Pacific predators almost uni-