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El Niño Effects on Galapagos

How the El Niño phenomenon affects the Galapagos Islands

The Galapagos Islands feature some of the most pristinely preserved natural ecosystems on the planet and host some of the world’s most vibrant biodiversity. Right at the vertex of three oceanic currents and formed on nutrient-rich volcanic soil and rock, these diverse ecosystems depend on various factors in order to survive, and their delicate balance is hinged on the constance of these factors. During El Nino years, when currents weaken and trade winds die down, the entire Galapagos food chain is impacted and many species face mass starvation and near extinctions.

Scientifically, the El Niño phenomenon is fascinating and still boggles oceanographers as to what causes it and how to predict it; but to the fragile Galapagos ecosystems, this occurrence is devastating.

One harrowing example illustrates just how powerful this phenomenon can be: The most recent strong El Niño events of 1982-83 and 1997-98 were followed by decimation of 77% and 65% of the penguin population, respectively.

What happened in the 1982-83 and 1997-98?

During an El Nino year, trade winds that typically blow warm water from the Ecuadorian Pacific towards the Asian Pacific die down; while this is happening, the Antarctic Humboldt Current, which jets cold water into the Galapagos Islands weakens. The combination of these two events impacts the process of “upwelling,” when the cold, nutrient-rich waters from deep in the ocean come towards the surface. When upwelling happens, phytoplankton and algae in the shallows can use the nutrients from the cold water in conjunction with the sunlight to reproduce via photosynthesis.

When these primary levels of the food chain are starved by the lack of nutrient-rich, cold water, there is a suffocating pressure on nearly all the species. Anything that gets its food from the sea suffers extreme starvation, and when populations of certain species die out in mass numbers, it shapes the evolution of the entire species.

Penguin, marine iguana, sea lion, and other species populations dropped to about half in the last super El Nino in 1997-98. The largest marine iguanas quickly starved, while the smaller ones shrunk their bodies even further to adapt to the decreased availability of algae. Sea lion colonies and Galapagos penguins that depended