Seat Otters and Kelp Forests: an Ecological History of the North Pacific Ocean

A Department of Ecology and Evolutionary Biology Seminar Series featuring JAMES ESTES, U.S. Wildlife Service (U.S. Geological Survey), UC Santa Cruz

Wednesday, October 23, 2013
12:00 PM - 1:00 PM
2320 Life Sciences Building

Abstract

My seminar will provide an overview and retrospection of the work my colleagues and I have done on sea otters and kelp forests over the past 43 years. I will first describe how sea otter populations have waxed and waned over the past two and half centuries and then explain how we have used these population changes to infer the influences of sea otter predation on the structure and organization of coastal marine communities. I will describe how sea otters initiate a trophic cascade that sweeps downward through herbivorous sea urchins to kelps and other fleshy macroalgae at the base of the food web. I will show that the transition between sea urchin barrens and kelp forests occurs as an abrupt phase shift with changing sea otter densities and explain why these alternate states are characterized by hysteresis. I will then describe a few of the many indirect effects on other species and ecological processes that spin off the sea otter-urchin-kelp trophic cascade. Next I will explain how these food web dynamics are influenced by linkage and connectivity over large scales of space and time. Finally, I will discuss several dimensions to the reciprocity between ecology and evolution in the sea otter-kelp forest system.

Host: Jamie Lloyd-Smith

Refreshments will be served at 11:40 a.m.