1. Keystone Species Species that have a large effect on an ecosystem
Take them away and the system collapses
© 2016 Paul Billiet ODWS

2. The case of the Californian sea otter
© 2016 Paul Billiet ODWS

3. Kelp forests Sea otters eat sea urchins Sea urchins eat kelp
© 2016 Paul Billiet ODWS
Sea otters eat sea urchins
Sea urchins eat kelp
Kelp forests act as ecosystems for many species and as nurseries for young fish
Hunting sea otters for fur impacted on the kelp forest ecosystems.
Sea urchins eating kelp

4. The wolves of Yellowstone Park
Grey wolves (Canis lupus) were considered a pest species
Hunted throughout western US
Exterminated from Yellowstone 1926
© 2016 Paul Billiet ODWS

5. The consequences Wolves hunt elk  Elk populations increase
North American Elk (Cervus elaphus)
Wolves hunt elk
 Elk populations increase
 Forest cover decreases
 Decrease in wetlands
© 2016 Paul Billiet ODWS

6. Yellowstone northern elk population
Culling of elk stops
© 2016 Paul Billiet ODWS

7. Not so simple
Though wolves are important predators on elk they are not the only factors
Disease
Drought
Fire
Other predators (e.g. grizzly bears)
© 2016 Paul Billiet ODWS