whale, krill & phytoplankton loop

Without whales, diatoms and krill sink into the deep sea, carrying with them nutrients required to fuel ocean production.

whale krill plankton.jpg

Ecosystem function is often thought to be controlled largely by plant production and the flow of energy and nutrients from plants to herbivores to higher level predators. We now know that large animals contribute to this dynamic in more complex ways. For example, wolves consume plant-eating elk, thereby enhancing the growth of trees; sea otters consume kelp-eating sea urchins, thereby enhancing kelp forests; and whales influence ocean ecosystems in numerous ways. One of the ecological pathways by which whales influence ocean ecosystems is via a cycle of increased production, represented by the artwork on this design. The cycle begins as diatoms capture the sun’s energy via photosynthesis near the ocean surface. Diatoms are eaten by krill and other zooplankton, which sink or swim to depths where they are eaten by various predators, including whales. Foraging whales must return to the ocean’s surface to breath, thereby fertilizing the ocean ecosystem by defecating and urinating in light-rich surface waters. Without whales, diatoms and krill sink into the deep sea, carrying with them nutrients required to fuel ocean production.

To learn more, visit erc.ucsc.edu.

 

Research

by James Estes, PhD,

Professor of Ecology and Evolution, University of California Santa Cruz