Wait, whale poop vs. climate change? How does that work? Let me try and explain.
Whales, especially the larger deep diving species like the Sperm whale and the beaked whales, are animals we would classify as ecosystem engineers. Ecosystem engineers are animals that modify, maintain and/or create a habitat. In the case of whales they maintain the ocean ecosystems, and they do this through the so called whale pump.
Before I dive into the whale pump, let's first talk about tiny marine organisms which float through the water column, which are the basis of the food web, I am of course referring to Phytoplankton. Phytoplankton are tiny microscopic marine algae that live in the surface of the sea, and which just like land plants use photosynthesis to live and grow. Beside photosynthesis, phytoplankton also need nutrients like: iron, nitrogen and phosphorus. However these are nutrients that sink to the bottom of the sea, through the so called biological pump. This is a downward pump of nutrients and resources which are vital for the marine environment. Now if these important nutrients for the phytoplankton are sinking and the Phytoplankton themselves can only stay at the surface where sunlight can penetrate (euphotic zone), how do these phytoplankton stay alive?
This is where the whale pump comes in. Whales dive to deep depths of the water column to feed, but they also need to breath at the surface of the sea. These diving and surfacing movements through the water column stir up the nutrients in the water column and cause some of these nutrients to reach the surface again. But these movements aren't the only way how whales influence and take care of the nutrients in the surface. The other way is through whale feces or whale poop. For whales, even though they have the entire water column at their disposal they prefer and can only do their needs at the surface. Whale feces are full with nutrients which feed the phytoplankton and cause phytoplankton to grow.
But what has this whale pump and the phytoplankton got to do with climate change?
Phytoplankton need photosynthesis to survive and in order to photosynthesis they, like all land plants, need both sunlight and carbon dioxide (CO2). CO2 is one of the main drivers of climate change, and we humans produce a lot of CO2. As you might know, all plants and trees use CO2 to produce organic matter, phytoplankton do exactly the same. A side product of this CO2 conversion is oxygen (O2), which we need to breath. Phytoplankton actually take in hundreds of thousands of tons of CO2 each year, which in turn produce 50% of all oxygen on our planet, which makes them just as important as all land plants for us humans as well.
What the whale pump shows is that whales are vital for the existence of phytoplankton and thus for the entire marine ecosystem. As phytoplankton are also the beginning of the marine food web.
In short, you could say that, more whales means more whale poop. More whale poop leads to more phytoplankton. And more phytoplankton can then take in more CO2, which would be an amazing help in our fight against climate change.
Sources:
Roman and McCarthy, 2010. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0013255
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