Download Powerpoint Presentation: Keystone Species

KEYSTONE SPECIES
Species that have a large effect on an
ecosystem
Take them away and the system collapses
© 2016 Paul Billiet ODWS
The case of the Californian sea otter
© 2016 Paul Billiet ODWS
Kelp forests
© 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
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
The consequences
• Wolves hunt elk
•  Elk populations increase
•  Forest cover decreases
•  Decrease in wetlands
North American Elk (Cervus elaphus)
© 2016 Paul Billiet ODWS
Yellowstone northern elk population
Culling of
elk stops
© 2016 Paul Billiet ODWS
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