| The change in trophic levels as a result of sea otter declines  |
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A trophic cascade is a process within the ecosystem in which a higher predator influences its prey such as lowering the population. Reduction in the amount of prey species results in the prey's food source being freed from exploitation. Trophic Cascades are an important part of ecosystems. Sea Otters in the Aleutian Archipelago provide an excellent example. Sea Otters act as a predator in a trophic cascade. Their interaction with sea urchins through predation leads to more kelp growth. As sea urchins feed on kelp, reduced levels of sea urchins allow kelp to flourish. This leads to more dense kelp forests and allows for many kelp forest species to thrive. As displayed in the graphs above, a decline in sea otters populations leads to an increase in sea urchin density and a decrease in kelp density. The ecosystem is no longer dominated by kelp forests and is driven by the sea urchins instead of sea otters. Sea otters release the kelp from predation by sea urchins. The kelp forest ecosystem is then able to persist and species that depend on it to thrive. Changing this relationship through a change in the abundance of sea otters leads to a different ecosystem construction which can lead to change in species composition or abundance. This example of a sea otter trophic cascade was observed ( Reisewitz et al. 2006).
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| Source: Produced By Simone Barker figure 2 or 2 Information gathered from (Reisewitz et al. 2006) and photos sea otter:wvoutpost.com, Sea urchin: animalcrossing.wikia.com, Kelp: www.californiasciencecenter.org |
1. Reisewitz, Shauna E, James A. Estes, and Charles A. Simenstad. "Indirect Food Web Interactions: Sea Otters and Kelp Forest Fishes in the Aleutian Archipelago." Oecologia. 146.4 (2006): 623-631. Print.
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