Trophic Cascade: Whales and Well-Functioning Systems

The video “How Whales Change Climate” by Sustainable Human on YouTube showcases how complex the systems within the biosphere can be. Whales are one of the few animals that evolved from land and returned to the water (McKinney, et al. 2019, 71). Whales became critical members of the oceanic biosphere and are now at the peak of a trophic cascade; an ecological process of nutrient movement that starts at the top of the food chain and works its way down (Sustainable Human 2014, 0:35). The interactions between different organisms creates changes to the other spheres, like the atmosphere, as well. Additionally, this nutrient system contains all the hallmark signatures of a highly functional system.

When viewing these biosphere interactions in systems terms, there are many different relationships between components and other spheres. The number of whales can be viewed as a stock in this system. Whales then produce waste from the fish and krill they eat. Whale excretions act as another stock from this feeding flow that generates the nutrients needed for phytoplankton stocks. Through the general food web, the phytoplankton also becomes food for zooplankton, and then larger animals like fish and krill that the whales eat again. However, these phytoplankton also absorb carbon from the atmosphere where it can be stored within the biosphere. When whales die, they fall the bottom of the ocean where they are deposited in the sediment which permanently sequesters the carbon (Chami, et al. 2019). This shows how the populations of whales, and their impact on the oceanic hydrosphere and biosphere, can then lead to the removal of tens of millions of tons of carbon from the atmosphere each year (Sustainable Human 2014, 3:30).

This complex biosphere system also showcases the critical aspects of a well-functioning system: resilience, self-organization, and hierarchy (Meadows and Wright 2008, 75). The different organisms in the ocean naturally form a trophic hierarchy, where the phytoplankton are eaten by zooplankton which are subsequently eaten by larger creatures like fish and krill that are then eaten by whales. These different niches of organisms were naturally developed through self-organization after whales had evolved from the land back into the sea. Resilience is showcased by examples where populations of fish or krill grow large and overfeed on zooplankton, the whales then eat the fish and krill in larger numbers which reduces the fish and krill’s impact to zooplankton while the whale excretions provide additional nutrients to phytoplankton that then can spur increased population regrowth of zooplankton due to increased food sources, allowing the system to maintain a dynamic equilibrium. This well-functioning system took thousands of years to develop and now is at risk of being destabilized due to activities of humans. The banning of whale hunting is a critical step to preserving this biosphere nutrient system that creates beneficial reductions of carbon in the hydrosphere and atmosphere as well.

Figure 1. Whale Impacts on Nutrients and Carbon

Source: (Chami, et al. 2019).

Author: Logan Callen


Chami, Ralph, Thomas Cosimano, Connel Fullenkamp, and Sena Oztosun. 2019. “Nature’s Solution to Climate Change.” Finance & Development 56 (No. 4): 34-38. Accessed June 30, 2021.

McKinney, Michael L., Robert M. Schoch, Logan Yonavjak, and Grant A. Mincy. 2019. Environmental Science: Systems and Solutions. 6th ed. Burlington, MA: Jones & Bartlett Learning.

Meadows, Donella H., and Diana Wright. 2008. Thinking in Systems: a Primer. White River Junction, VT: Chelsea Green Pub.

Sustainable Human. 2014. “How Whales Change Climate.” YouTube. November 30. Accessed June 30, 2021.

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