FACT OF THE WEEK: Whales play a crucial role in the carbon cycle

MORE ON THIS: In a previous Fact of the Week, we learned how plankton helps the oceans ‘biological pump’, a process that supports the global carbon cycle by removing carbon from the air and storing it in the deep sea. This week, we’re going to talk about the largest living creatures in the ocean, whales, and their role in the carbon cycle. Their movements, deaths, and even feces all contribute to the ‘whale pump’ which works with the biological pump to promote carbon storage.

Movement: When whales swim from deep waters to the surface, they move nutrients up with them. Bringing nutrients to the surface increases the food source for phytoplankton, which play the first part in carbon uptake.

 

Death: When dead whales sink to the ocean floor, they take with them all the carbon that has built up in their body over their lifetime. As the largest marine mammals, that’s a lot of carbon, similar to the huge amounts of carbon stored in old trees.

Feces: When whales swim to the surface, they poo, releasing large fecal plumes which are extremely nutrient-rich and widely consumed by plankton. As one of the larger whale species, sperm whale poop alone might remove hundreds of thousands of tons of carbon from the atmosphere by promoting plankton growth.

Before population declines due to industrial whaling, it is estimated that large baleen whales used to remove millions of tons more carbon than they do today. Scientists suggest that restoring whale populations could greatly increase ocean carbon storage again and may be just as effective as reforestation projects and ocean iron fertilization.

By Kaitlin Yehle

 

FURTHER READING:

  1. Whales Keep Carbon out of the Atmosphere.
  2. The Impact of Whaling on the Ocean Carbon Cycle: Why Bigger Was Better.
  3. Whales as marine ecosystem engineers. Frontiers in Ecology and the Environment. Roman J, Estes JA, Morissette L, Smith C, Costa D, McCarthy J, Nation JB, Nicol S, Pershing A and Smetacek V. 2014. 12(7): 377-385.

 

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