







Biosphere

Peruvian Fisheries Upwelled systems of the ocean are cold areas high in nutrients and productivity. Consequently, diverse ecosystems and large marine fisheries develop there. During an El Niño, upwelling decreases, the thermocline lowers, and the warmer water near the surface lacks the nutrients found during cold conditions. Beginning in the 1950s, an important anchovy fishing industry developed and grew in Peru, utilizing the huge numbers of anchovies that lived in the areas of cold, nutrient-rich waters welling up off the Peruvian coast. By 1971, the Peruvian anchovy harvest had climbed to 12.5 million tons per year. However, in 1972, an El Niño year, the anchovy stocks declined sharply. Only 2.5 million tons were harvested that year, leading to great economic hardship and a virtual collapse of the Peruvian fishing industry. Left: Photo courtesy of www.arttoday.com. The failure of the anchovy harvest in 1972 was blamed on El Niño, but overfishing had also played a part. Harvests prior to 1972 had been over the 9.5 million tons that fishery experts had estimated as the sustainable limit for the fishery (NOAA, 1997). Even so, the collapse of the anchovy stocks was further evidence that El Niño could affect not only the atmosphere and ocean, but also the biosphere. Worldwide Biosphere Events As scientists and economists studied the effects of El Niño on the Peruvian fishing industry, they soon realized that the decrease in the anchovy population had triggered a series of interrelated problems. For example, much of the anchovy catch is processed into fishmeal. During the growth years of the Peruvian fishing industry, the fishmeal had become a major source of feed for livestock and poultry around the world. When the anchovy catch collapsed in 1972, nations around the world that had become dependent on the fishmeal had to find other, more expensive, sources of feed. This caused meat prices to rise. In the United States, poultry prices rose more than 40% (Ahrens, 1994). Another result of the drop in the anchovy population was the death of many birds, such as guanay and piquero birds, which had depended on the anchovies for food. The death of the birds, aside from being a tragic loss in itself, caused a decrease in the harvest of bird droppings which had become an important source of fertilizer for Peruvian farmers (Amaral, 1997). Thus the loss of the anchovies affected not only Peruvian fishermen, but also Peruvian farmers. Right: Photo courtesy of Photo Disc, Inc. Other correlations of El Niño with biospheric events worldwide have been recognized. In both the southwest United States and South Africa, rodent infestations occur after El Niño rains. Typically, non-El Niño years in these areas are dry. During the dry years, populations of both the rodents and their predators, such as owls and snakes, are reduced. When the heavy El Niño rains come, food for the rodents becomes suddenly abundant. The rodent populations expand more rapidly than the predator population, quickly leading to an infestation of rodents (Epstein, 1997). In southern Asia, El Niño events have been recognized since the 1960s to be correlated with algal blooms and cholera outbreaks. Across the globe, wherever weather changes brought about by El Niño give rise to warmer and wetter conditions, mosquito populations mushroom, leading to an increase in mosquito-borne diseases such as malaria, yellow fever, dengue fever, and encephalitis. Truly, El Niño is not simply an obscure curiosity of interest only to scientists, but a periodic alteration of the global climate and biosphere that affects the daily lives of millions of people. [ Atmosphere ] [ Biosphere ] [ Hydrosphere ] [ Lithosphere ]

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