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  • Here's the latest from EarthNow

  • For the past 15 years, satellites that measure the color of the ocean have given us a view

  • of sea surface phytoplankton which form the base of the food web and half of all the oxygen

  • we breathe.

  • These satellite data are being used to understand fish distributions and why some fisheries

  • suddenly collapse.

  • In these monthly composites, high amounts of phytoplankton in the ocean are shaded green

  • to yellow for the most. Water with little to no phytoplankton is dark blue.

  • Phytoplankton abundance is controlled by the availability of sunlight and nutrients. Winds

  • over the ocean drive currents away from the coast and equator, creating a void at the

  • surface that’s filled by nutrient-rich water from the deep ocean upwelling to the sunlit

  • surface.

  • Combining satellite data with samples collected from the ocean enables scientists to better

  • understand where these microscopic plants live and support different ecosystems and

  • how physical and chemical changes affect them.

  • Seasonal changes are most obvious. Slower changes are also apparent, one of the largest

  • being El Nino in the tropical Pacific, with an approximately 5 year cycle. El Nino causes

  • reduced upwelling, with warmer water and less phytoplankton; its opposite phase is called

  • La Nina with more phytoplankton than normal.

  • Since phytoplankton form the base of the food web in the ocean, they impact animals higher

  • up the chain. A major consequence of El Nino is the loss of commercially important species

  • from their usual location: anchovies around South America, squid off of California, salmon

  • around the Pacific, and others. Not only fish are impacted, but animals that

  • depend upon them such as sea lions, seals and sea birds experience famine.

  • Understanding El Nino and other natural and man-made causes for fisheries collapse will

  • guide decisions about how to help them recover.

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B1 phytoplankton el nino nino ocean food web fish

Effects of El Niño/La Niña on Phytoplankton and fish

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    Bing-Je posted on 2013/12/12
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