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Niño year. For example, in Chile and Peru, thousands of seabirds died during the 1982-1983 El Niño, and the valued ecosystem of Ecuador's Galapagos Islands was disrupted (Ribic et al., 1992; Trillmich and Limberger, 1985). In California, the warmer coastal waters of El Niño years reduce the fish populations that support seals and other marine mammals, resulting in die-off and reproductive failures (Shane, 1994). Coral reefs are also vulnerable. They experience bleaching under warm water stress and can have high mortality rates in El Niño years (Glynn, 1984). Some species, however, such as shrimp and scallops, flourish in the warmer waters of these years. Managing fluctuations in marine mammal and bird populations is difficult, especially when conservation might involve cutting back on commercial fisheries. Groups have attempted to rescue a few mammals and provide emergency food supplies to birds.

Many riparian and grassland ecosystems are also highly sensitive to climatic variability. Coping systems affecting livestock production on grassland ecosystems are discussed in an earlier section. However, there is significant climate-related variability in the populations of less-managed species in riparian and grassland systems, including breeding birds and amphibians in marshes and wetlands and grassland wildlife populations ranging from rodents to grazers to large carnivores. Severe droughts in southern Africa, for example, are often associated with large-scale mortality of wildlife.

Water Supply and Flood Management

Climate-driven variability in supply is a fundamental characteristic of surface water resources. Various water management entities around the world have planned their infrastructure and operating procedures in response to expected variations in hydrologic conditions. In the United States, these entities range from individual irrigators and domestic water users who control their own water supply systems to federal agencies that oversee the operation of complex multiunit, multiple-purpose water storage, control, and delivery systems. Institutional contexts, which differ markedly between the arid western and humid eastern states, shape the efforts of water users and the large variety of public water managers to cope with variable streamflows. Similarly, other countries have developed institutions and infrastructure for water control and allocation that are the product of particular physical, climatic, and social circumstances. Such arrangements include small-scale traditional irrigation systems that are often managed according to complex allocation rules designed specifically to cope with the effects of variable water supplies, as well as large-scale modern irrigation projects, typically managed by agents of the central government.