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We all know whales and dolphins are awesome in their own right, but did you know that their bodies and even their poop can provide nutrients to other animals and even help combat climate change? Read on to see how marine mammals impact other animals and how they are critical to the health of the ecosystems and oceans they live in.

Poop To Save The World

We are all looking for a way to combat climate change, and specifically reduce the amount of excess carbon dioxide (a major greenhouse gas) that is being released into the atmosphere every year.  But I don’t think anyone thought, you know what, I think whale poop is the answer!  I mean, who thinks about whale poop anyway? Well, luckily some researchers did! 

It all starts with phytoplankton – the microscopic photosynthesizers that are the base of the marine food web (think of them like little trees), produce 50% of the oxygen in our atmosphere, and capture 40% of the carbon dioxide produced every year.  Talk about tiny powerhouses!

Now how is whale poop involved? Well, these phytoplankton need sun and so are found close to the surface.  They also need nutrients, particularly nitrogen and iron, but these are often in limited supply in these waters.  But luckily whale poop is high in nutrients like nitrogen, iron and phosphorous – a great fertilizer!  Because whales have to breath at the surface, they are usually pooping in shallower water than they feed in (unlike other species like fish, that eat and poop at the same depth).  The fat content of the poop makes is float, bringing those nutrients right where they are needed: to the phytoplankton!

This movement of nutrients vertically in the water column is an important part of nutrient cycling in the marine environment. While most large whales will dive to catch food, sperm whales may take the prize as the farthest nutrient movers: they can feed at depths over a mile down! Thus large whales are feeding in deeper waters (and thus taking the nutrients from there), and then releasing those nutrients in surface waters where phytoplankton happily take them up, often resulting in phytoplankton blooms.

Why is that important? Well, remember phytoplankton are the base of the food web.  So if there are a lot of phytoplankton, then there is a lot of food for other zooplankton, fish and whales!  A specific example is that baleen whales eat krill (planktonic crustaceans), and krill eat phytoplankton. So, by pooping at the surface whales are helping to ensure their own food supply, as well as for so many other animals.  In fact, commercial krill fisheries worried that increasing whale numbers would impact their catch, but it may just be that the whales will actually stimulate rather than suppress plankton abundance!

Ok, so whale poop creates lots of phytoplankton, but how is that connected with climate change?  Remember what I said at the beginning about their ability to capture carbon? Phytoplankton are carbon sinks, so the more there are, the more carbon dioxide is taken in! This reduces the amount of that greenhouse gas that is trapped in the atmosphere and the effects that has on the Earth’s climate.  Prior to whaling it was estimated that baleen whales (and their poop) used to remove millions of tons more carbon from the atmosphere than they do today. A 1% increase in phytoplankton productivity (due to whale poop) would capture hundreds of millions of tons of additional carbon dioxide/year.  This is the same as the sudden appearance of 2 billion trees (and takes up a lot less space)!

Whales poop increases phytoplankton productivity and all the benefits that go along with it, including increasing plankton populations (and food for other species), more oxygen production and combating climate change through removing carbon dioxide from the atmosphere.  Thus by saving the whales, we may help save the planet. Talk about a win-win situation!

Whale Falls

While whales are critical components of an ecosystem during their lifetime, they are also vastly important to other species upon their death. When a whale dies, the massive body often sinks to the deep sea, becoming what is known as a whale fall. These whale falls are incredibly important for organisms that dwell on the seafloor that depend on scavenging. With gaps in foraging for deep sea creatures often taking months at a time, a whale fall provides an oasis to the desert seafloor. This oasis can create its own ecosystem for many years, lasting longer in these deeper waters due to the fewer organisms living there. These whale falls initially provide literal tons of organic material, with opportunistic scavengers (such as small fish, crustaceans, and even larger sharks) foraging the buffet. Once the tissues are stripped from the carcass, other animals contribute to the decomposition, such as “bone-eating worms.” These worms (only recently discovered due to whale falls) acidify the whale’s bones to bore into them, using their symbiotic bacteria to digest what lipids remain within the bones. Finally, this process produces bacteria colonies and sulfur in the water, allowing for the colonization of a “reef stage” of sedentary organisms onto the whale’s bones, such as clams or mussels.

Initial decomposition of tissues by mobile consumes of a whale. Photo: Ocean Exploration Trust?NOAA

One exciting theory from these benthic communities suggested whale falls may provide “evolutionary stepping stones” for specific organisms. The theory proposes that due to some animals utilizing the sulfur produced from the whale’s decomposition, this environment may have contributed to the adaptation of animals living at deep-sea hydrothermal vents (habitats engulfed in sulfuric water) or offering those who depend on sulfur to geographically expand their range – that is, the whale falls may offer the necessary environmental materials as “pit stops” for species to expand throughout the seafloor. 

Hydrothermal vent communities are highly sulfuric. Whale falls may offer opportunities for sulfur-dependent organisms to leapfrog across the sea floor, or offer the chance for organisms to evolve sulfuric conditions and eventually proliferate in sulfuric environments. (Photo: University of Victoria).

cindy.elliser@pacmam.org

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