What are keystone species (consumer)?
A species who's presence determines the community structure
• Have significance to the community out of proportion to their abundance
o E.g., relationship between sea otters and the sea urchins on which they feed
• As long as the sea otters are protected, we have healthy kelp cores, coral controlled, shellfish controlled.
• Introduction of humans
Took commercial shellfish
Took the sea otters
• Deprivation of fish → decrease* in seal and sea lions → Killer whales had to begin taking sea otters
• The sea otter was the corner stone of its community
o E.g., Pisaster (sea star) is another keystone species
• Work by Robert Paine
In the absence of Pisastar, 1 mussel dominates the community & crowds out other organisms
Community diversity and complexity are reduced
Pisastar determined community structure