El Nino, El Coyote, and the Birds
How Water Temperature in the Eastern Pacific Means Life or Death for Seabirds
Oct 2, 2006
In Floods, Famines, and Emperors (Basic Books, 1999), Brian Fagan writes that 24 million seabirds starved to death in the eastern Pacific in 1925. Dead cormorants, pelicans and other sea birds rotted along the shorelines and in the coastal waters. Other sea life died in vast numbers as well. It sounds like an environmental disaster - it wasn’t because of an oil spill or a red tide, however. It was El Nino.
In a normal year, the coastal waters of the Eastern Pacific, particularly off the coast Peru, and California in the United States, teem with algae, krill, small fish and other food for larger fish, birds, and marine mammals. The prevailing winds, blowing from east to west, push warm surface waters away from the coast with such unrelenting strength that ocean water actually piles in the western Pacific. The westerly movement of surface water causes colder water from below to move up and fill the gap, bringing abundant nutrients with it. It is this upwelling of water and influx of nutrients that supports a staggering amount of sea life in these locations.
In some years, El Nino years, the winds fail to move the surface water sufficiently to bring on a powerful upwelling of cold rich water. In these years, the food chain is disrupted – marine life waiting for the annual feast goes hungry and fishers relying on a good catch have a bad year. El Nino weather also brings abnormally heavy rainfall causing flooding in coastal areas as the unusually warm water evaporates into the air. When El Nino effects are particularly severe, there is widespread starvation like the terrible death toll of 1925.
Beyond the immediate effect on wildlife and coastal people, El Nino has significant implications for global climate that are still not entirely understood. Abundant research has made it possible, however, for scientists to predict and observe an El Nino year with considerable accuracy.
In 2005, the annual movement of warm water away from the California coast, followed by an upwelling up cold water full of nutrients from the depths, didn’t have its usual punch. Colonies of Cassin’s Auklets, an auk species that relies on ocean fish for food, abandoned their nests on the Farallon Islands en masse. Populations of fish and other birds also suffered. The same thing happened in 2006. It wasn’t El Nino.
We don’t know why California is experiencing El Nino effects in the absence of El Nino. The best guess is that climate change has disrupted the prevailing winds and ocean currents in some way that isn’t understood yet, and it remains to be seen whether the scenario will continue to repeat itself. The name El Coyote has crept into the language of scientists to describe this unpredictable and tricky phenomenon.
Meanwhile, El Nino is expected for 2007: the seabirds of the California coast are almost certain to have another bad year.
Related blog entry: El Coyote?
