I (Tamara) wrote this entry [a couple years ago] while on my yearly week-long pilgrimage to Pacific Rim National Park, located on the west coast of Vancouver Island, British Columbia, Canada. The rugged coastline of this park holds endless stretches of beach – paradise for surfers, beachcombers, and biologists alike. This entry, the first of a series on the Coastal Flora of the Pacific Rim, features one of the most intriguing species commonly encountered on the beach. I took this photo of a washed-up Nereocystis luetkeana on Long Beach. For incredible underwater images of this species, visit the online gallery of photographer Jackie Hildering.
Nereocystis luetkeana, or bull kelp, doesn’t grow on the beach, but it is often found washed up on the sandy shore. A regular summer day on Long Beach will reveal many mounds of bull kelp at varying stages of putrefaction. The freshly-arrived bull kelp has a rubbery texture unlike that of any other plant species I have encountered. Children fling it around like lassos, or use the incredibly long stipes (like stems) as skipping ropes. Older piles of washed-up Nereocystis luetkeana attract other types of creatures. Small kelp flies (Coelopidae) flit around the decomposing kelp blades, while sand fleas (Megalorchestia) hop in and around the piles of kelp in great numbers.
Bull kelp is surely of ecological importance to the transient sand flea communities, but its most celebrated ecological contributions come from stands that are still growing. Above sea level, the Pacific Rim is host to some of the most majestic forests in the world. Although not as obvious, the Nereocystis luetkana forests within the ocean are equally impressive. Stands of bull kelp reach up to 25 metres tall, and provide food and shelter for many sea creatures. The article Ecology and Management of bull kelp, Nereocystis luetkana (pdf) discusses the role of this species as a nursery for juvenile fishes and as a hunting ground for sea birds, otters, and predatory fishes. Bull kelp is also an incredibly useful plant for humans. On my last day in Tofino, I went on a guided kayak tour into one of the nearby inlets. My guide happily munched on the kelp fronds for much of our journey, claiming that he hadn’t had much for breakfast. The leaves are salty and a bit rubbery, but actually quite good. My guide gave me a recipe for fried kelp rings. Simply soak a hollow part of the stipe in fresh water to remove some of the salt, then slice it up, dip into a batter and deep fry. Yum!
Much of the rocky Pacific North American coast is host to this incredible species. It grows in the upper subtidal zone, near rocky shorelines. Deep under the water, a root-like structure termed a holdfast anchors the bull kelp to large rocks. From the holdfast emerges the long stipe, which is solid and narrow at first. The stipe gradually increases in diameter and becomes hollow as it approaches the surface of the water. At the top of the stipe is a carbon monoxide-filled bulb; a float that keeps the seaweed upright even in the turbulence of Pacific coast storms. The long kelp leaves emerge from the top of the bulb and float at or near the water’s surface, forming dense canopies that capture much of the sun’s energy. During the summer and autumn, when sunlight is abundant, Nereocystis luetkeana sporophytes can grow up to 6cm per day. Although not necessarily an annual plant species, many bull kelp are ripped from their holdfast during winter storms. Once this occurs, they cannot regrow.
The book Indian Fishing: Early Methods on the Northwest Coast, written by Hilary Stewart, covers some of the ways that Nereocystis luetkeana was used in traditional fisheries. Stewart describes bull kelp as “ideally suited” for the making of fishing lines. The solid part of the stipe was soaked, stretched, and twisted. Individual lengths were tied together using a fisherman’s knot to give the fishermen very long, strong lines. The bull kelp bulb was also used in the process of making bentwood hooks. A diagram in Stewart’s book shows how fir sticks were placed in Nereocytis luetkeana bulbs and buried under hot ashes to steam overnight. In the morning the bulb was removed from the ashes and split open, revealing the steamed sticks which could then be bent and placed into a mold.