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Science 21 January 1977:
Vol. 195. no. 4275, pp. 285 - 287
DOI: 10.1126/science.195.4275.285
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Articles

Biological Consequences of the 1975 El Niño

TIMOTHY J. COWLES 1, RICHARD T. BARBER 1, and OSCAR GUILLEN 2

1 Duke University Marine Laboratory, Beaufort, North Carolina 28516
2 Instituto del Mar del Peru, Callao

The weak El Niño event of 1975 had a clearly defined effect on the biological productivity of the southeastern tropical Pacific. During February and March 1975, warm (27°C) water of low salinity (33.5 parts per thousand) and low nutrient content extended south across the equator east of the Galápagos Islands, replacing the nutrient-rich water normally supplied by equatorial upwelling. Equatorial primary production was less than 0.2 gram of carbon per square meter per day, one-fifth of the normal value. At the maximum development of the 1975 event, the coastal region of Peru continued to have strong nearshore upwelling with primary production values greater than 2.5 grams of carbon per square meter per day, although the zone of high production was confined to a 250-kilometer-wide band, one-half its normal width. The biological effects of the 1975 event were short-lived; in April and May 1975 the equatorial region had begun to reestablish its normal levels of primary production.

Submitted on August 2, 1976
Revised on September 21, 1976


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Biological Consequences of El Nino.
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Atmospheric Carbon Dioxide, the Southern Oscillation, and the Weak 1975 El Nino.
R. B. BACASTOW, J. A. ADAMS, C. D. KEELING, D. J. MOSS, T. P. WHORF, and C. S. WONG (1980)
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Breeding Patterns of Galapagos Penguins as an Indicator of Oceanographic Conditions.
P. D. BOERSMA (1978)
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