A Perspective on El Niño and La Niña: Global Implications for Stream Ecology

Abstract

Analyses of flow data for the Gila (60 years) and Pecos (68 years) Rivers in New Mexico showed that spring flows during snowmelt were significantly increased during El Nino years (periods of elevated sea surface temperature and reduced barometric pressure in the eastern tropical Pacific) and significantly decreased during La Nina years (periods of reduced sea surface temperature and elevated barometric pressure). Over the period of record for these two rivers, mean spring runoff during El Nino years was 2.3-3.2 .times. higher than during medial years and 6.0-7.4 .times. higher than during La Nina years. The results of this study indicate a strong correspondence between El Nino-Southern Oscillation (ENSO) phenomena and stream flow in New Mexico. These results also suggest that, in this region, the increasingly accurate, and remote forecasting of ENSO phenomena, often months in advance of the event, could be used to place future studies of biotic responses to variation in flow on a more predictive basis. Since it has been shown that ENSO phenomenon affects the weather of large portions of the North American continent and tropical and subtropical regions worldwide, a similar potential for improved study design exists for other regions.