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"The number of living creatures of all Orders, whose existence intimately depends on the kelp, is wonderful...I can only compare these great aquatic forests with the terrestrial ones in the intertropical regions." — Charles Darwin, naturalist
 | Senorita © R. Mickens / AMNH |
Kelp provides essential food and habitat for numerous other species—including economically important fish, lobster and abalone. Kelp itself is also collected for food, fertilizer and alginates, which are used to thicken many foods. But pollution and global warming could threaten the ability of even this resilient seaweed to survive. And ravenous sea urchins can raze entire kelp forests if their numbers are not kept in check by sea otters, lobster and fish such as California sheephead—all of which are threatened by human activity.
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Sea otter eating urchin
© Jeff Foott / Bruce Coleman, Inc. |
Colonies of voracious sea urchins have been known to eat their way through entire kelp forests, leaving behind barren rock. In healthy ecosystems, urchins are held in check by otters and other predators. Though no longer hunted, sea otters are now threatened by pollution-caused diseases and oil spills. And other key predators of urchins, such as lobster and sheephead, are subject to heavy commercial fishing, disrupting the balance of the kelp forest habitat.
Human-induced global warming threatens giant kelp in two important ways. Altered weather patterns cause violent storms that can tear kelp loose from the bottom. Hotter climate patterns can also suppress upwelling of cold, nutrient-rich water from the depths, which giant kelp depends on to survive.
Kelp is eaten by people, fed to animals and collected for industrial chemicals and fertilizer. It is also harvested for algin, a creamy thickener used in ice cream, salad dressing, cosmetics, dyes, pies and many other consumer products. But while the kelp can grow back, unregulated removal of the canopy can temporarily destroy vital nurseries for young fish and deprive other animals of nutrients.
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