Crusty old Joe's

Kodiak Alaska Military History



The official web site of the Kodiak Military History Museum


THE NATURALIST
by Dave Evans

A Good Year for Sushi
July 27, 2004

Tidepooling at Monashka Bay has been a little different this year. It's been a great season for seaweed at the Ram Site, and I don't quite know why. The dense covering in the middle intertidal zone makes us move the rockweed aside even to see into some of the tidepools. Bright green sea lettuce-major wrapping material for sushi-grows in thick clusters among the rockweed. Out beyond the intertidal zone the floats of bull kelp are more dense than I've seen them, and large pieces wash up and get stranded on the beach after storms.

The Monashka Bay seaweeds are marine algae and considered almost, but not quite, plants. They have no seeds or roots, nor do they have tissues that transport nutrients. Instead, they need to take in nutrients from the surrounding seawater over the entire body surface. They do have their own specialized features, in the form of holdfasts that anchor them to the bottom, floats or bladders that give buoyancy, and leaflike blades where the main concentrations of chlorophyl for photosynthesis are located. Seaweeds occur in green, red, and brown forms, based on types of pigment present in addition to green chlorophyl.

Many reproduce by releasing cells directly into the water, and the body form reflects this necessity. Reproductive organs of rockweed are at the bladder ends of the two-pronged blades, keeping this part of the blade up in the water column. Reproductive cells are released as waves dash against the blades. Sea lettuce has thin delicate blades (only two cells in thickness!) that waft back and forth in the moving water, while cells at the edges of the blades release the reproductive products. The float of bull kelp keeps the reproductive area high up in the water. The float also holds the long blades up close to the surface where there's plenty of light.

As marine algae, the major seaweeds of Monashka Bay do have similarities, but they also have their own distinctive characteristics.

Bull kelp is our largest and most conspicuous seaweed beyond the intertidal zone. It's also our fastest-growing, adding up to two feet per day, and reaching lengths of 200 feet within a single year. It's one of the brown algae, with the scientific name Nereocystis, which means...and I wouldn't make this up... "bladder-equipped sea nymph." The air-filled kelp bulb is presumably the sea nymph's head, and the 10-foot long blades extending from the bulb are the hair. I thought this was a stretch in descriptive naming until finding that a traditional pastime among kids growing up on the Island is to carve jack-o-lantern faces in the bulbs, pretend the blades are hair, use a stick for the body, and have puppet shows, or...just chase each other around giggling with the little figures. Fun with bull kelp never stops.

Bull kelp is a valuable part of Kodiak's ecosystem, serving as food and habitat for fish and invertebrates, and as an anchor for sea otters as they secure themselves in kelp beds to keep from drifting while they sleep. Dead kelp along the beaches is a food source for scavengers and decomposers. Considering the amount that washes ashore, I imagine there's a greater contribution to the flow of ecosystem energy from dead kelp than from the living. Bull kelp has its more direct uses to humans, as pickles and cooked or candied kelp. Its high trace mineral content makes it an effective nutritional supplement. The bulbs have been used as containers and extracts serve as thickeners in ice cream or salad dressings. It has medical value, possibly shortening fracture healing time or regulating an overactive thyroid.

Rockweed (Fucus)is our dominant rock cover on Monashka Bay and the beaches around Miller Point. Because of the inflated ends of the two pronged blades, it also goes by names like bladderwrack or poppingweed. It can be popped just like bubblewrap, and it's just as hard to stop popping after you've started on a patch of prime inflated bladders. Unlike bubblewrap, rockweed can be eaten raw, stirfried or added to soups as a thickener. The liquid inside the bladders is similar to aloe vera; we smear it on barnacle scrapes incurred by our tidepoolers. It may also be useful as a thyroid stimulant for weight loss or in a liniment for joint aches.

Sea lettuce (Ulva) is one of the green algae. Its bright green blades have the look of lettuce leaves kept in a refrigerator with an out-of-adjustment temperature control. In addition to its use in sushi, it can be dried as seasoning, served raw in salads, added to soups, or cooked and buttered. Medicinally, the fresh blades can be applied directly to the skin to sooth sunburn.

A low tide look at the Ram Site beach this year shows an impressive amount of living material, and most of it is seaweed. The seaweeds are an important and often taken for granted part of our environment on the Island. Because of their abundance and their position as photosynthesizers at the base of the food chain, they are a real component of the way things work in this Kodiak Island habitat.

David A. Evans, Summer Naturalist
Fort Abercrombie State Historical Park.


http://www.kadiak.org/naturalist/sushi.html Updated 2004 July 27

www.ka diak.org