Olympic Coast National Marine Sanctuary Living Sanctuary section includes Marine Life, Habitats, Ocean Environment, History and Culture
Olympic Coast National Marine Sanctuary Living Sanctuary section includes Marine Life, Habitats, Ocean Environment, History and Culture
Olympic Coast National Marine Sanctuary Living Sanctuary section includes Marine Life, Habitats, Ocean Environment, History and Culture

Kelp Forest

photo of fist swimming in a kelp forest Off the coast, beyond the crashing surf, where the ebb and flow of the ocean currents bathe shallow reefs, sways the majestic kelp. Kelp occurs along coastlines that have an upwelling of cool, nutrient-rich waters, with temperatures usually 68 degrees Fahrenheit. Dense stands of these brown algaes are called kelp forests.

photo of a kelp forest These beautiful and biologically productive habitats are found in shallow, sunlit waters - usually less than 30 meters deep - from the Arctic to the Antarctic Circles. The bull kelp, scientifically known as Nereocystis, is one of the largest and fastest growing kelps in the world, attaining astonishing growth rates of up to 10 inches a day. Bull kelp typically reach lengths of 60 feet or more in a lifespan of 1-2 years.

photo of fish in kelp forest The kelp plant is "anchored" to the seafloor by a root-like structure called a holdfast. At the top of the holdfast grow stem-like stipes. These reach toward the surface with the help of a hollow bulb, called a pneumatocyst. At the tip of the bulb are fronds, the function of which is to absorb nutrients directly from the water column and gather light energy for photosynthesis. At the surface, the fronds continue to grow, forming a dense canopy.

photo of a jelly in kelp forest The canopy is teeming with juvenile fish and invertebrate larvae, which in turn may feed seabirds such as the marbled murrelet, a threatened species along the Pacific Northwest coast. Other predators in the kelp forest include the sea urchin. Population explosions of the herbivorous urchin can decimate a kelp forest. At the top of the complex kelp forest food web is the sea otter, which can help control the urchin numbers.

photo of kelp on rocks Native Americans had many uses for kelp, including medicine, food, salt, and fishing gear. Modern day uses include the extraction of algin, which is used in everyday products such as paints, synthetics, pharmaceuticals, rubber, beer and toothpaste.


June 1, 1834. The number of living creatures of all Orders, whose existence intimately depends on the kelp, is wonderful. On shaking the great entangled roots, a pile of small fish, shells, cuttlefish, crabs of all orders, sea-eggs, star-fish, beautiful crawling animals of a multitude of forms, all fall out together. I can only compare these great acquatic forests with the ones in the intertropical regions. Yet if in any country a forest was destroyed, I do not believe nearly so many species of animals would perish as would from here, from the destruction of the kelp.

- Charles Darwin, "Voyage of the Beagle"



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