food webs

food webs - Secondary consumer Omnivore Architectural...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Primary Producer Primary consumer Secondary consumer Omnivore Architectural metaphors in ecology: Keystones Keystones: have a big effect despite low abundance Trophic cascades in kelp forests… Urchins can overgraze kelps, leaving nothing but crustose coralline algae that are grazer- resistant. When otters are present, urchin densities are reduced, increasing kelp biomass Humans hunted otters to near extinction in much of California in the 1700’s but they have made a comeback in central California
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Otters maintain high population densities in much of Alaska, but recently some populations have declined… why? Killer whales Adding another trophic level to the cascade Estes et al. 1998 … urchins are increasing… Where otters are declining… … and kelp is disappearing. ODD vs. EVEN # of trophic levels determines effects of removing top predators Why are orcas suddenly eating otters? Otters are all that’s left in some areas… why?
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 4

food webs - Secondary consumer Omnivore Architectural...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online