 |
|
Home -- ENSO Cycle -- ENSO Effects -- Missions -- Data -- Tools -- Site Map |
|
||||
Central and Eastern Equatorial Pacific Ocean
Introduction
The effects of warm water events on the fisheries of Peru and Ecuador have been known for a long time, but were thought to be local in nature. Only with the "severe El Niño" of 1982-83 was the attention of scientists around the world focused upon the ENSO Cycle and the distant regional to global effects. Local effects are discussed on this page; regional and global effects are discussed on other pages.
The reversal of surface trade winds (NSCAT wind data) may first take place in the western Pacific in May, but the impacts are felt in the eastern Pacific. Abnormally warm surface waters (Pathfinder SST data) migrate east under the influence of the reversed trade winds. Generally the first impacts of El Niño conditions in the eastern Pacific include an increase in precipitation (TOVS rain data) (TRMM TMI rain data) in the eastern Pacific (including parts of South America) and a decrease of precipitation in the western Pacific. Over time, tropical storm activity (TRMM LIS lightning data) increases in the eastern Pacific.
Fisheries and Marine Life
During an El Niño season, the surface temperature of the ocean will rise by as much as 3 degrees Celsius while the upwelling of cold, nutrient-rich waters will stop. As a result, the diatoms and phytoplankton that are normally abundant all but disappear. Researchers used NASA's Sea-viewing Wide Field-of-View Sensor (SeaWiFS) satellite to watch chlorophyll levels (SeaWiFS chlorophyll data) plunge in December 1997 to the lowest measurements ever recorded. Further up the food chain, the anchovies, which prefer cooler water temperatures, migrated to lower depths where cooler water and phytoplankton were available. This made them inaccessible to the nets of the fishing fleets as well as to guano-producing birds. Stocks of sardine and other pelagic species from Ecuador migrated southward toward the Peruvian-Chilean coast causing a reduction of 57 percent in total landings for 1997 with respect to 1996. Both Peruvian and Chilian governments declared a ban on anchovy fishing. Overfishing in an attempt to have a "normal" harvest during an El Niño season results in a decline in future stocks.
Coastal Peru experienced nearly summer temperatures during July and August 1997 (normally the coldest winter months), in excess of even those for the 1982-83 El Niño. By late July 1997, warm-water fish migrated south along the coast of Peru, and the anchovy likewise moved south. Animals that feed on the anchovy either migrated to where more food was available, starved to death or did not reproduce. Off the coasts of Peru and Ecuador, when fish stocks plummeted, local populations of seals, sea lions, Humboldt penguins, and seabirds such as gulls and terns were devastated. CNN reported that Peruvian Brown pelicans invaded the town of Arica in northern Chile, wandering down streets looking for food.
Species of fish that prefer the warmer waters moved into the coast. Tuna, marlin, and swordfish, all foreigners to the Latin American coast, were taken in large numbers by fishing boats in Ecuadorian and Peruvian waters. In addition, large amounts of scallops and shellfish, which are less common under normal conditions, were available under the El Niño conditions.
1 month before other indications of the start of the La Niña, (SeaWiFS chlorophyll data) recorded an explosion in phytoplankton growth around the Galapagos Islands as warm El Niño waters were replaced by deep, cold, upwelled waters.
Jump to 'Fisheries and Marine Life' List of Web Sites
Drought and Floods
The coastal and island populations of Ecuador were dramatically affected during the 1997-98 El Niño season. Increases in sea level and wave action, due to Kelvin waves from storms in the northern Pacific, caused coastal erosion at the shoreline, destroying any structures near the beaches. The rainy season extended longer than normal; the resulting increases in rainfall (TOVS rain data) (TRMM TMI rain data) along the coastal provinces produced flooding, mudslides, infrastructure destruction, collapsed bridges, and agricultural devastation. Poor sanitary conditions became health problems, leading to epidemics of cholera and other diseases. Most of the flooded cities had problems with water supply, sewage, and damage to their infrastructures. The rural populace suffered the most because of isolation; flooding destroyed highways, bridges, and dry-season roads, which are the lifelines of the rural poor to the cities.
Harvests and agricultural products were lost, raising market prices. Excess rainfall affected the size of the planted areas of different crops: bananas, sugar cane, rice, and soy. Air temperatures and cloudiness negatively affected some fruit plants, like mango, by preventing them from flowering.
Jump to 'Drought and Floods' List of Web Sites
Disclaimer: NASA offers these suggested sites for additional information regarding effects of El Niño and La Niña events. Web access is required to reach these sites. Link existence and contents are not under the control of the EOSDIS Science Operations Office.
Local Fisheries and Marine Life Web Sites
Local Drought and Floods Web Sites