Seaweed

by Ela Keegan
Reviewed by: Shep Erhart, Seraphina Erhart, Jaclyn Robidoux, Chris Petersen, Natalie Springuel, Gaelen Hall

 

“Neither plant nor animal
I cover the globe but am rarely seen,
I sway in the wind, but cannot stand on land,
People eat and use me every day
Without knowing it
Food of the past, food of the future
What am I?”

-Kaori O’Connor, Seaweed: A Global History

 

When we think of vegetables, most of us think of produce grown in the soil, a valuable and hearty product from the ground on which we live. However, more and more people are expanding this definition to include vegetables from the ocean. Seaweed, as far back as the Pleistocene era, has historically played a vital role in marine ecosystems and human resources for sustenance, nutrition, medicine, and fertilizers. With a recent increase of Western interest and knowledge of sea vegetable’s nutritional, environmental, social, and artistic value, sea vegetables have quickly become labeled as a superfood. While seaweeds were once considered no more than waste, forming a slimy and decomposing layer on a seemingly pristine coastline, they are slowly gaining value. As attention towards seaweed has grown, Downeast Maine communities—including fisheries, scientists, harvesters, and farmers—have increased the value and distinction between different seaweeds.

This brief exploration focuses on the historical harvesting and uses of edible sea vegetables from when human ancestors first settled in this area through to the formation of an established seaweed industry. For current uses of sea vegetables, their harvesting, and farming from the 1960s until today, refer to Fisheries Now: Seaweed.

What is a Sea Vegetable?

“Seaweed” is the overarching term given to marine macroalgae which can be separated into three main divisions: (1) Rhodophyta – Red seaweeds (2) Phaeophyta – Brown seaweeds (3) Chlorophyta – Green Seaweeds (Purcell, 2015). For our purposes, “Sea Vegetable” is the name given to a small subset of green, red and brown edible seaweeds on the coast of Maine that are consumed by people directly. The color distinctions between seaweeds is related to biology, but also roughly reflect human’s historical and modern uses. Green and red seaweeds are consumed fresh or raw, while brown seaweeds, not normally viewed as sea vegetables, are used as fertilizer, bondants, emulsifiers and thickeners. An example of a brown seaweed on the coast of Maine is Ascophyllum nodosum— also known as rockweed, knotted kelp, knotted wrack, or egg wrack.

Biological Breakdown of Seaweed

Seaweed is found in all five areas of the world’s ocean, from the equatorial regions to the Poles, and is crucial to the environments and ecosystems in which it exists. It provides important nursing grounds and food for fish and other animals and provides nutrients to the marine environment. Seaweeds are eukaryotic, multicellular, marine algae, also called macroalgae (Purcell, 2015). This means that they are simple, aquatic organisms made of multiple cells that are genetically determined by DNA. Together with microalgae (single-celled algae), macroalgae, including seaweeds, are believed to provide up to seventy-five percent of our planet’s oxygen.

Seaweed’s Tree of Life

Seaweeds are the predecessors of land plants and serve similar ecological roles as their terrestrial descendants. Scientists today are clear in separating the classification of plants from the red, brown, and green seaweeds. This can be seen below in algae’s “tree of life” (Graham, 2016).

While it seems today that there is clear distinction between plants and algae, this has not always been the case. The scientific categorization of seaweed has been historically disputed, because scientists were unsure whether to classify them as plants or within the more general category of marine life (O’Connor, 2017). Historically, seaweeds have more often been categorized alongside terrestrial plants, because they are both photosynthetic. Photosynthesis is the process in which seaweeds and plants create energy by absorbing sunlight, synthesizing nutrients from carbon dioxide and water, and producing oxygen as a by-product (Purcell, 2015). This involves the presence of chlorophyll, which gives both plants and (some) seaweeds their green pigment. Because of its need for sunlight, seaweed lives within the ocean’s photic zone, which includes the intertidal. The photic zone is the oceanic layer which receives sunlight and spans to a depth of around 100m depending on location, ocean depth, and energy of the ocean’s surface layer (Pinet, 2011). The depth at which seaweed grows within the photic zone is dependent on the particular species as well as the availability of nutrients such as carbon, nitrogen, and phosphorus that seaweeds absorb (Jacobsen, 2017). The need for constant access to sunlight is why most seaweeds developed a holdfast, which acts as an anchor, attaching them to a surface, such as coral, a rock, or a line. This is where plants and seaweeds become difficult to compare. While plants are made of roots, stems, and leaves which they use to grow on land, seaweed is composed of a holdfast, a non-vascular stipe, and blades which allow them to grow in water.

A seaweed thallus refers to the entire body of a seaweed in which the main components are the holdfast, stipe, float or air bladder, and blades (MESA, 2015). The holdfast is the structure at the base of the seaweed which attaches it to a surface. Seaweeds do not have an internal structure like plants do. Due to their constant consistent contact with ocean water, different parts of algae absorb and accumulate different concentrations of nutrients. The stipe is the central part of algae which predominately creates structure and is distinct from the rest of the blade. Typically located somewhere on the stipe, but dependent on the particular species is the air bladder and the blades. The air bladder, otherwise known as the float, keeps the seaweed floating close to the surface to maximize the amount of sunlight the blades can absorb (Williams, 2019). Blades, or lamina, are the flattened structures resembling leaves. They are the main location of photosynthesis in seaweed. They also form canopies on the ocean’s surface, providing important shelter to nursing species (MESA, 2015).

Historical and Cultural Importance of Seaweed

For the better part of the 1900s, it was commonly believed that the first human descendants in North America were the Clovis hunters. They were thought to have traveled through an ice-free corridor along the coast of the Pacific and into the United States at the end of the Pleistocene Era (10,000 years ago). According to research from the last several decades, this theory has several flaws, and seaweed plays a role in debunking long-held assumptions. First, the flaws include the oldest known Clovis site (10,000 to 15,000 years ago) discovered in Texas (not in Canada as previously assumed) (Hirst, 2018) and a general lack of proof that there was an ice-free corridor. Second, and immediately relevant for our story, another flaw in the theory was revealed in 1977 when seaweed traces were discovered at the coastal archaeological site of Monte Verde in Southern Chile (Dillehay, 2008). Traces of nine different species of macroalgae were found on human bones, teeth, and pots, believed to be used for both sustenance and medicine (Dillehay, 2008). Due to the ease with which macroalgae decomposes, it is difficult to find evidence of their use and consumption prehistorically, except in Monte Verde where the soil and climate created a unique condition for their preservation.

As a result of these findings, the Kelp Highway Hypothesis was proposed. This hypothesis theorizes that the North Pacific Coastline’s rich kelp forests—stretching along the coastlines of what is today Japan, Alaska, Canada, and the United States of America—supported early human dietary needs as they migrated up and down the coast (Hirst, 2018). This incidentally also supports the Coastal Migration Theory which hypothesizes that groups of human ancestors before the Clovis hunters traveled down the West coast of the Americas and across to the East coast, sustaining and supporting themselves with marine resources. Between 14,200 and 13,980 years ago, until today, seaweed is theorized to have been an important part of human life in the “new world” (Dillehay, 2008). This also supports the theory that our earliest human ancestors, who lived on what is today called Downeast Maine, depended on seaweed.

 The Downeast Area

Seaweed has historically had great significance to the Downeast region’s marine ecosystems, the region’s earliest human ancestors, the Wabanaki people, and European colonizers. This area has been an incredibly productive environment for a range of sea vegetables including sugar kelp, edible kelp, Irish moss, and dulse. This productivity is because of the cold, nutrient rich waters brought to Maine’s coast by oceanographic currents. However, while the presence of seaweed has been consistent in the Downeast area’s culture, human uses and consumption of these species have changed overtime. This change is most clearly marked by the period of Wabanaki settlement followed by the period of European colonization.

Wabanaki uses of sea vegetables

The Wabanaki people in the Downeast area of Maine, including the Mi’kmaq, Maliseet, Passamaquoddy, Penobscot and Abenaki nations, have inhabited this land for thousands of years (Abbe Museum). During this time, sea vegetables were used in a variety of ways including as flavoring, snacks, and an important source of nutrients. The Abenaki and the Micmacs were considered to be the “clam cultures,” as is visible in the shell middens that line Maine’s coast (Stettner, 2010). In the traditional clam bake, the soft-shelled clams were wrapped in wet seaweed and placed onto hot rocks to steam. Different sea vegetables were also used to flavor the clam bakes and stews which were frequently eaten during the summer months (Sanger, 1986, p.151). Sea vegetables, such as dulce, were an important source of sodium, iodine, and greens in the Wabanaki people’s diet (Harper, B., & Ranco, D. (2009). They were harvested from the coastline, dried on the beach, and eaten raw, like seaweed crisps (Harper, B., & Ranco, D. (2009).

European Colonizers use of sea vegetables

In the early 1600s, along with the arrival of the first European colonizers, the way sea vegetables on the coast of Maine were used and consumed began to change (Stettner, 2010). In 1647, an ordinance was passed stating that the beach up until the low tide mark was private land except for colonists engaged in “fishing, fowling or navigating,” as long as the private shorefront property was not crossed to access it (Goldfarb, 2018). This ordinance was passed in an attempt to encourage property owners to invest in shorefront development such as wharves and docks in order to pursue the European colonizers primary fishery: cod (Daly, 1989), but it would impact the diversity of fisheries undertaken near shore.

During these years, the seaweed fishery, comprised of sea vegetables and rockweed, clearly differentiates in both uses and volume. Sea vegetables began to form the “nucleus of a cottage industry” (White, 1992). It was harvested, dried, and sold predominantly as food and a source of iodine, potassium and minerals that were used in industry and medicine, such as antibiotics, insecticides, and anticoagulants (White, 1992). It has also been documented as an “additive in soups, stews and stuffing” (Slade, 2007). Rockweed on the other hand was used industrially and for fertilizer, colloquially gaining the nickname of “sea-manure” (Goldfarb, 2018).

Sea vegetables have historical importance to the Downeast area of Maine since the earliest human inhabitants until our traceable ancestors. However, it is still a relatively small commercial fishery. The first landings data was documented by Maine’s Department of Marine Resources in 1964. In this data, sea vegetables and rockweed are combined under the category of seaweed, despite their historical differentiation in uses and quantities harvested. While seaweed has historically been harvested from wild populations, there has only been an established commercial industry for the past fifty years and an aquaculture fishery for the last ten years (Maine Sea Grant, Resources for Seaweed Growers). Over the last fifty years, the sea vegetable fishery has increased in landings, number of wild harvesters, aquaculture sites, and public demand.

To learn more about the sea vegetable industry today, please read the Fisheries Now: Seaweed.

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References for Edible Sea Vegetable Fishery Then:

• Abbe Museum. (n.d.). About the Wabanaki Nations. Retrieved from https://www.abbemuseum.org/about-the-wabanaki-nations
• Daly, C. B. (1989, July 16). COURT RULING STEMS TIDE OF BEACH-GOERS IN MAINE. Retrieved from https://www.washingtonpost.com/archive/politics/1989/07/16/court-ruling-stems-tide-of-beach-goers-in-maine/736f04bf-7f56-4d1f-b06e-2ed3545dcc35/?noredirect=on&utm_term=.c0106166cf2e
• Dillehay, T. D., Ramírez, C., Pino, M., Collins, M. B., Rossen, J., & Pino-Navarro, J. D. (2008, May 09). Monte Verde: Seaweed, Food, Medicine, and the Peopling of South America. Retrieved from http://science.sciencemag.org/content/320/5877/784.full
• Four Directions Development Corporation, FDDC. (2001). Wabanaki Tribes. Retrieved from http://www.fourdirectionsmaine.org/wabanaki-tribes/
• Goldfarb, B. (2018, May 30). How Seaweed Connects Us All. Retrieved from https://www.smithsonianmag.com/science-nature/seaweed-connects-us-all-180969199/
• Graham, I. Graham, J. Wilcox and M. Cook IJLM Press (2016). Algae, 3^rd Original diagram modified with permission by Jaclyn Robidoux.
• Harper, B., & Ranco, D. (2009). Wabanaki traditional cultural lifeways exposure scenario. Environmental Protection Agency, Washington, DC.
• Hirst, K. (2018, January 26). Kelp Highway Hypothesis Theorizing the Diet of the First Colonists in the Americas. Retrieved from www.thoughtco.com/kelp-highway-hypothesis-171475.
• Jacobsen, R. (2017, March 30). Seaweed Dreaming. Retrieved from https://newengland.com/yankee-magazine/today/seaweed-dreaming/
• Madlener, J. C. (1977). The Sea Vegetable Book: Foraging and Cooking Seaweed. C.N. Potter.
• Maine Sea Grant. (n.d.). Resources for Seaweed Growers. Retrieved from https://www.seagrant.umaine.edu/aquaculture/resources-for-seaweed-growers
• (2015). Marine Algae. Marine Education Society of Australasia. Retrieved from http://www.mesa.edu.au/marine_algae/
• Monterey Bay Aquarium. (2019). Education. Retrieved from https://www.montereybayaquarium.org/education
• O’Connor, K. (2017). Seaweed: A Global History. Reaction Books.
• Pinet, P. R. (2011). Invitation to oceanography. Jones & Bartlett Publishers.
• Purcell, A. (2015, May). Seaweed | Basic Biology. Retrieved from https://basicbiology.net/micro/microorganisms/protists/algae/seaweed
• Sanger, D. (1986). An introduction to the prehistory of the Passamaquoddy Bay region. American Review of Canadian Studies, 16(2), 139-159.
• Shetterly, S. H. (2018). Seaweed Chronicles: A World at the Water’s Edge. Algonquin of Chapel Hill.
• Slade, D. C. (2007). White Paper on the Public’s Right of Seaweed Harvesting in the State of Maine. Retrieved from https://www.seaweedcouncil.org/wp-content/uploads/link-for-white-paper-in-Who-owns-the-seaweeds-of-Maine.pdf
• Stettner, L., Morrison, B., & Hinckley, S. (2010). Cooking for the common good: The birth of a natural foods soup kitchen. Berkeley, CA: North Atlantic Books.
• White, S. and M. Keleshian (1992). A field guide to economically important seaweeds of northern New England. University of Maine/University of New Hampshire Sea Grant Marine Advisory Program.
• Williams, R. (2019, March 02). What Is the Function of Air Bladders in Seaweed? Retrieved from https://sciencing.com/function-air-bladders-seaweed-8003965.htm