Group Members: Leslie Epps, Reid Vero, Nicole Budzinski

Research Question: How does the presence of sea otters affect kelp and sea urchin populations in the Aleutian islands?

Hypothesis: If we compare similar marine habitats, some with sea otters and some without, then we will see a large population of kelp and a small population of smaller sea urchins in habitats with sea otters. We will also see a large population of larger sea urchins and a smaller population of kelp in habitats without sea otters.

Method:

  • Choose similar locations within the Aleutian Islands – some with sea otters and some without
    • Habitats with similar water temperatures, landscapes, etc.
  • Randomly pick points in these locations to be used for an estimate for the populations of the entire location.
  • Measure sea otter and kelp forest populations in sites.
  • Measure sea urchin populations in these sites and the average size of sea urchins in these populations.
  • Compare the kelp forest population of sites with an abundance of sea otters to the populations of habitats with a low amount of sea otters.
  • Repeat this experiment over the course of five years.

Background:

Sea otters are considered a keystone species, in that other species in their surrounding ecosystem depend on them for survival. These animals help maintain sea kelp forest by eating the sea urchins that destroy them. This process is known as trophic cascade. Without the top predator, the sea otter, the sea kelp would be depleted by the prey, the sea urchins. Kelp forests are important because they absorb inorganic carbon from the environment for photosynthesis and subsequently release oxygen back into the environment, which increases the growth rates and population size of many consumer species.

Citations:

Estes, J. A., & Duggins, D. O. (1995).  Sea Otters and Kelp Forests in Alaska: Generality and Variation in a Community Ecological Paradigm.  Ecological Monographs, 65, 75-100.

Estes, J. A., Tinker, M. T. and Bodkin, J. L. (2010), Using Ecological Function to Develop Recovery Criteria for Depleted Species: Sea Otters and Kelp Forests in the Aleutian Archipelago. Conservation Biology, 24: 852–860. doi:10.1111/j.1523-1739.2009.01428.x

Dean, T., Bodkin, J., Jewett, S., Monson, D., & Jung, D. (2000). Changes in sea urchins and kelp following a reduction in sea otter density as a result of the Exxon Valdez oil spill. Marine Ecology Progress Series, 199, 281-291. Retrieved from http://www.int-res.com/articles/meps/199/m199p281.pdf