Kelp Forest Food Web
Marine
Eastern Pacific — California to Alaska
Description
Pacific kelp forests form towering underwater ecosystems where giant kelp can grow up to 60 cm per day. Sea otters maintain forest health by preying on sea urchins that would otherwise overgraze the kelp. This three-level trophic cascade is one of the best-documented examples of top-down ecosystem control.
Trophic Pyramid
Level 5
Decomposers
Kelp-degrading bacteria
Amphipods
Isopods
3 species
Level 4
Tertiary Consumers
Great white shark
Orca
Harbor seal
3 species
Level 3
Secondary Consumers
Sea otter
Sheephead wrasse
Spiny lobster
3 species
Level 2
Primary Consumers
Purple sea urchin
Abalone
Kelp snail
3 species
Level 1
Producers
Giant kelp
Bull kelp
Coralline algae
3 species
Apex Predators
Tertiary Consumers
Secondary Consumers
Primary Consumers
Producers
Key Interactions
- Sea otters control sea urchin populations, preventing kelp overgrazing
- Without otters, urchin barrens replace productive kelp forests
- Giant kelp provides three-dimensional habitat for over 800 species
- Kelp detritus supports nearshore and deep-sea food webs through export