Trophic cascades paper (3 short papers)
Read the papers in chronological order (start with the 1974 Science paper first, then the
Estes 1998 Science paper then the 2003 PNAS paper)
Estes and Palmisano (1974) Sea otters: Their role in structuring nearshore communities.
Science 185:1058-1060
Estes et al. (1998) Killer whale predation on sea otters: linking oceanic and nearshore
communities. Science 282:474-6 (Notice how this paper is constructed)
Springer AM et al. (2003) Sequential megafaunal collapse in the North Pacific Ocean: An
on-going legacy of industrial whaling?
Short bonus paper: Steinberg et al. (1995) Evolutionary consequences of food chain
length in kelp communities. PNAS 92:8145-8148
Questions:
What are the keystone species in this system?
What lines of evidence are used to show that otters are important predators on urchins?
How is the food web of the near-shore community linked to pelagic and terrestrial food
webs?
Why is kelp so susceptible to grazing?
What are the “implications for the approach to and scale of other ecological field
studies”?
What evidence is used by Springer et al. to argue against bottom up control of sea lion
populations?
What might you conclude from the Springer et al. paper about the future recovery of the
great whales?
What approach did Springer et al. use to evaluate whether killer whales could account for
the population declines of sea otters and sea lions?
Why have community level influences of whales and whaling had so little effect on
subsequent research?