El Niño's impact on phytoplankton • Earth.com

El Niño's impact on phytoplankton


El Niño years can cause a ripple effect through the ocean’s food chain, a new study found, and now NASA is trying to figure out the how and why.

El Niño is warm phase of an oscillating pattern in the tropical regions of the Pacific Ocean. El Niño years generally lead to warming in the Pacific, which in turn sparks temperature disruptions and rainfall in regions around the ocean. Some areas, however, receive less rainfall due to the warming, such as Indonesia.

While the obvious signs of El Niño are the weather patterns seen above the sea’s surface and on land, it can also have an effect deep below the waves. When warm water caused by the El Niño pattern disrupts ecosystems deep underwater, it can cause ripples through ocean food chains, and even affect fishing in coastal regions.

For example, on the South American coastlines of Chile and Peru, currents of cold water – called upwelling – bring nutrients that feed tiny sea life like phytoplankton closer to the surface. When the warmth of El Niño prevents upwelling from happening, essentially keeping the cooler currents in deeper waters, many of those tiny organisms starve.

When there’s not enough phytoplankton to eat, the animals that feed on them – shrimp, jellyfish, blue whales and more – don’t have enough food, and those populations begin to dwindle.

The trend continues until the fishing industries of Chile and Peru are affected.

The problems caused by suppression of upwelling aren’t limited to South America; they occur all over the Pacific during El Niño years.

Fortunately, phytoplankton and other microorganisms that rely on upwelling rebound quickly, the NASA scientists said.

The agency is using satellite imagery to monitor blue and green chlorophyll in the Pacific during El Niño and La Niña years. Green chlorophyll brought closer to the surface by upwelling is a food source for phytoplankton while blue chlorophyll is not, allowing scientists to note when an area is a good habitat for the tiny creatures.

They believe the data they’re collecting will offer insight into how phytoplankton process and contribute to carbon in the ocean.

And, of course, it can also help fisheries predict when they might have a tough year.

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