What is Alaria Seaweed? Ecology and Human History of Alaria esculenta
Alaria (Alaria esculenta) is a brown seaweed species usually found ten to thirty or more feet below the high tide line in the sub-tidal zone. The color ranges from golden-brown to a rich deep brown. Alaria attaches to rocks and ledges with a small claw-like holdfast, and it often grows in thick beds. The blade is typically long and narrow, soft and flexible, and often pointed at the tip. Alaria esculenta is easily recognized for having a distinctive midrib up the blade and several small sporophyll ‘wings’ at the base. The midrib is an extension of the short stipe (stem), and its presence makes it hard to confuse Alaria with other brown kelp species also found in the Atlantic. The sporophyll wings at the base of the frond are reproductive structures that are also unique to Alaria. Mature plants are generally 1-1.5 meters (3-5 feet) long and sometimes longer.
Scientific & Common Names
The Latin word Alaria originally referred to the wing of a Roman army, but with the seaweed it’s in reference to the wing-like sporophylls (spore bearing leaves) found at the base of the stipe. Alaria goes by several common names, which vary depending on region. In the Northwest Atlantic, along the eastern seaboard of North America, Alaria is often known as winged kelp, and the Latin name Alaria esculenta literally translates as ‘edible wing’.
Line drawing of Alaria esculenta. Notice the wing-like sporophylls at the base of the stipe
Alaria is also known as ‘wild Atlantic wakame’ because of its biological and culinary similarity with Japanese wakame (Undaria pinnatifida). The two species are related as laminarian kelps, and like Alaria, Undaria blades have a distinctive mid-rib. Undaria was originally found only in cold coastal waters of Japan, Korea, and China, but in recent decades it’s become established in temperate regions all around the world. Because Undaria can displace local species and change ecosystems, it has been nominated as one of the 100 worst invasive species. Undaria hasn’t yet become established in the Gulf of Maine and it’s too soon to know if will displace our native Alaria if it does.
In much of Europe, Alaria is called badderlocks, dabberlocks, or even honeyware. In Ireland, Alaria may be known by its Gaelic names láir or láracha. The origins of these names appear lost in the mists of time.
Life History & Ecology
Although we often use the term plant when referring to Alaria, like all other brown seaweeds it isn’t closely related to plants, animals, or even to red or green seaweeds. However, like plants, Alaria is photosynthetic and contains chlorophyl and other photosynthetic pigments. The genus Alaria consists of 8-10 recognized species. They all have a circumboreal distribution (northern hemisphere) and in general Alaria prefers rocky shores with strong wave exposure. Alaria esculenta is the only Alaria species found in the Atlantic, as well as along Russia’s Siberian Chukchi peninsula. This makes it the most widely distributed Alaria species.
Temperature is the most critical limiting factor determining where Alaria grows. Alaria esculenta prefers cool water of about 12°C (54°F), and mature plants can’t survive long in water warmer than 16°C (61°F). The northern extent of its range is the southern limit of arctic sea ice, and in the Atlantic Alaria isn’t found any further south than Cape Cod on the US east coast or the French coast of Brittany.
Interestingly, Alaria esculenta gametophytes can tolerate warmer water up to 20°C, as can the portion of the plant consisting of the stipe and sporophylls. This means that as the fronds die back in late summer, the reproductive portion can survive to reproduce in autumn. Alaria has a reproductive cycle characterized by an alternation of two generations, where it takes on a different form each generation. Technically, this is known as a heteromorphic, diplohaplontic life history. In the first generation, the sporophylls (the ‘wings’ at the base of the stipe) release haploid zoospores (containing half the full complement of chromosomes), which can swim a short distance until they find suitable substrate to settle upon.
After settlement, the spores germinate to form microscopic gametophytes, which may be either male or female. This is the 2nd generation. The gametophytes develop through three stages, the third one being reproductive. If conditions aren’t favorable this third stage may grow vegetatively to form a filamentous structure until conditions improve for reproduction. When conditions are favorable, female gametophytes form egg-like oospores and males develop spermatozoids. The oospores release a pheromone that attracts spermatozoids, and fusion occurs to form zygotes. Each zygote then germinates into a diploid plantlet (containing the full complement of chromosomes), which then develops into the mature sporophyte plant of the 1st generation.
Growth from zoospore release to diploid plantlet takes place over 2-4 months, mostly in late fall. Once established, Alaria plantlets grow quickly with maximum growth occurring in October-November and February-May. It’s said that in May the fronds can grow one foot per week. They reach peak size and quality April-June, after which they become overgrown with epiphytes (algae that grow on other algae) and gradually decay. Some people consider Alaria to be an annual kelp because beds in the intertidal zone die back each fall. However, individual plants can survive for up to 7 years and others regrow from the holdfast, seeded by the sporophylls. This means Alaria can be considered a perennial.
Alaria beds occur in thick, mono-specific (single species) stands, and they tend to reliably reappear in the same locations year after year. Mussels, herbivorous snails, and sea urchins are often found associated with Alaria beds but these invertebrates aren’t necessarily dependent on them. When sea urchins are abundant, they can completely remove Alaria beds, resulting in ‘urchin barrens’. Other than sea urchins, Alaria has no major predators and there are no known diseases or other pests that pose a significant threat. Storms or winter ice scour can sometimes remove entire beds.
History of Use
Alaria has long been a traditional food in European and Native American coastal cultures, and the Japanese ate its close relative wakame for thousands of years. In Ireland, Scotland, and Iceland Alaria was often served as a vegetable or salad leaf, though it could be cooked as well. Alaria is the preferred sea vegetable of the Chukchi people, the native inhabitants of coastal Siberia, who enjoy its fresh midrib in winter and spring.
Alaria is also used as animal fodder in many northern coastal regions. It can be added at about 5% to 10% to replace traditional proteins in poultry feed, and at somewhat higher levels to feed cattle, horses, pigs, and sheep. Icelanders would wash freshly harvested Alaria and then store it in trenches with a layer of stones or oak planks on top to serve as a winter feed supplement for dairy cows. This didn’t affect the flavor or odor of dairy milk but it likely added iodine and, in that fashion, contributed to healthy humans.
Alaria is flavorful without being overwhelming. It has a salty, minerally flavor that’s well balanced with a savory umami flavor and a hint of nuttiness. Fresh Alaria is a treat, especially the succulent mid-rib, but sadly, it’s only available to coastal residents who know where to harvest or know someone who does (never eat seaweed washed up on the beach!).
Most people enjoy Alaria in its dried form. Maine Coast Sea Vegetables sells dried Alaria as whole leaf or powdered. It’s also included in our Kelp Blend granules. Dried leaf is hard and crunchy but it quickly softens with chewing and is good eaten right from the bag as a raw snack. One of the more popular uses of Alaria leaf is as a substitute for traditional wakame in miso soup, though it needs a longer cooking time. Powdered Alaria adds flavor and nutrition to soups and broths, while Kelp Blend granules, which contain Alaria and rockweed, are a great all-around seasoning.
The cookbook Irish Seaweed Kitchen by Prannie Rhatigan has over 40 recipes that include Alaria as an ingredient. Recipes for Alaria pesto, Alaria and banana loaf, and Alaria Malaysian honey chicken testify to the versatility of this sea vegetable.
Nutritional & Medicinal Attributes
Alaria is rich in minerals such as calcium, iron, potassium, and magnesium. It’s also high in iodine, though it usually contains less than other brown sea vegetables such as sugar kelp, rockweed, or bladderwrack. This makes Alaria a good choice for those wanting to enjoy the nutritional & medicinal benefits of brown seaweeds but with less iodine. Alaria also contains vitamins; notably vitamins A, B2 (riboflavin), B3 (niacin), and C (ascorbic acid). Alaria is a good source of dietary fiber and it has a respectable protein content…about 12% in the dried product, the most of any brown sea vegetable.
Brown seaweeds such as Alaria are rich in a range of bioactive compounds that are of great interest to scientists. These compounds include structurally complex carbohydrates (polysaccharides) that are resistant to digestion, making them dietary fiber. As dietary fiber, seaweed polysaccharides improve our intestinal health. Beyond that well demonstrated benefit, however, seaweed polysaccharides come in a variety of structural forms that show multiple beneficial bioactive properties in lab studies. These polysaccharides include fucoidan and laminarin, both of which are unique to macroalgae, and having anti-cancer and anti-inflammation properties.
Brown seaweeds also contain fucoxanthin, a carotenoid pigment responsible for the plants’ olive brown hue. Fucoxanthin is a powerful anti-oxidant, and studies show that fucoxanthin extracts have anti-cancer, anti-diabetic, and anti-obesity effects. A recent study showed that Alaria esculenta contained almost three times more fucoxanthin than sugar kelp, another brown seaweed.
Alaria is relatively high in polyphenols, a subset of bioactive antioxidant compounds. Polyphenols may contribute to the antitumor properties of Alaria seen in some studies. Finally, Alaria may have phytoestrogenic properties. Jane Teas published a study in 2009 showing that Alaria favorably altered estrogen and phytoestrogen metabolism for women at high risk of estrogen-dependent disease or experiencing fertility problems.
Wild Harvest & Processing
Currently, most of the world’s Alaria supply comes from wild harvest. Alaria can be challenging to harvest because it’s most abundant on surf-battered ledges well below the high tide line, in the lower reaches of the sub-tidal. Harvesters refer to the Alaria crop as annual beds and perennial beds, corresponding to shallower and deeper depths. Annual beds found at shallower depths are almost exposed at low tide and therefore subject to more extreme conditions. These beds may completely disappear every season and must be reestablished with gametophytes released from perennial Alaria. Perennial beds found at greater depths remain covered at all times, and the plants flourish under the protection of deeper water. Even though the fronds may die back at summer’s end, the holdfast and sporophylls survive to regrow the following winter and reseed the annual beds.
Alaria is sustainably harvested by cropping only from annual beds. Harvesters access the beds at low tide by boat, though they may have to exit the boat and wade in the water to harvest. Harvest takes place in a narrow window of time in late spring/early summer, after the plants put on their most growth but before they become tattered and worn by sun, waves, and weather. The plants are cut with a sharp knife just above the holdfast. The northern Gulf of Maine is brisk and bracing this time of year, so harvesters may wear wet suits to keep warm. Since Alaria grows on ledge and rocks, the footing can be slippery and precarious. All of our Alaria is sustainably wild-harvested from the Gulf of Maine and Certified Organic.
Once the heavy, wet fronds are loaded and the boat is filled, the harvester brings the crop to shore. Fresh Alaria has a short shelf life and needs to be dried within 24 hrs. of harvest. Alaria is usually hung to dry like clothes on a line. This can be done outdoors under the sun but greenhouses are preferred, sometimes equipped with wood stoves or other heaters, and fans for circulation. Alaria can also be laid in a single layer on clean rocks or tarps to dry, though this is less common. It takes about two days to dry to the proper level of between 15-19% water content. Dried Alaria has a long storage life of 5+ years when properly stored in dry, cool, conditions away from direct light.
The abundance of bioactive compounds in Alaria has generated interest in farming it at industrial scale strictly for bio-extraction of these useful substances. Farming methods would be based on those used for Undaria (wakame) in Asia. Wakame cultivation techniques were first developed in 1943 at Dalian, northeast China. By the 1950’s it was being grown at commercial scale in Japan, mostly in Onagawa Bay, Miyagi Prefecture. In 2016, over 2 million tonnes of Undaria were harvested from farms in Japan, Korea, and China. Farming methods first developed for Undaria are readily adapted for Alaria farming.
The past three decades have seen gradual development of Alaria cultivation, mostly in Europe and more recently in Maine. The earliest reference to Alaria farming dates from 1991, when a group led by JM Kain used twine seeding methods to cultivate Alaria in the Isle of Man. Today, several small companies located in the UK and Norway grow a few tonnes each of Alaria esculenta each year. In 2010, the first Alaria farm was established in the Gulf of Maine by Ocean Approved (now known as Atlantic Sea Farms). Several small companies now cultivate Alaria in Maine, and although production levels are still quite low, kelp cultivation is one of the fastest growing aquaculture sectors in the northeast US. So far, most Alaria cultivation is done by small scale ‘family farms’ for human consumption. This level of production is widely viewed by experts as sustainable, and indeed as conferring numerous benefits to local ecosystems. Research shows that seaweed mariculture can help buffer local ocean pH, absorb carbon, and provide habitat for other species.
Alaria mariculture follows the natural rhythms of wild Alaria, though early life stages occur in hatchery labs instead of the sea. In the fall, reproductive zoospores collected from fertile sori are seeded onto seed string in aquaria, where the ensuing gametophytes follow the same developmental sequence into juvenile sporophytes (seedlings) as they do at sea. After seed strings become established and the seedlings are 1-2mm, they’re brought to the ocean lease site and wound around ropes. These are held horizontal and in place with moorings, and the plants grow through the winter for spring harvest.
In some ways, Alaria is the perfect agricultural crop. It requires no fresh water or irrigation, no pesticides or herbicides, and no fertilizer. There’s no tilling or weeding, and so far, experience has been it doesn’t suffer from pests or disease. In other ways, though, Alaria cultivation is very challenging. Start-up costs include a motorized working vessel equipped with a lifting hoist; an aquaculture lease; purchase and placement of grow-out lines and heavy moorings; and seed costs. Consideration must be given to where and how the crop will be dried, processed, and marketed. Ocean farmers must be comfortable working on the water and operating boats. They have to understand local tides, currents, and other sea conditions, while being careful to not affect others who depend on the ocean for livelihood or recreation. Finally, the fact remains that, for now at least, Alaria is not what one would consider a high value crop.
Despite these challenges there remains strong interest in kelp aquaculture, and we believe it has great potential to address the need of a growing population for healthy food produced in a sustainable fashion. For now, though, we rely on the wild Alaria harvest, which we know from over 40 years of experience as a company can be sustainably managed.