Thursday, November 3, 2011

Simply Unique Seaweed

Seaweed is one of the simplest, most unique, and interesting plants.  But calling seaweed a plant is a slight misconception.  Technically, seaweed is not like the land plants we commonly encounter, seaweed is actually an algae.  What's the difference between plants and algae?  Land plants are much more complex, they absorb nutrients and water through extensive root systems, and have vascular systems to distribute these through out the plant.  Algae on the other hand have no root system, instead they have a holdfast, which simply anchors them to the ocean floor.  Instead of a stem, algae have a stipe, which is like a stem but does not contain woody vascular tissue.  Lastly, algae may have what looks like leaves but actually are called lamina because they also lack vascular tissue.  Nutrients, instead of being absorbed from the soil, through the roots, and then transported to the leaves through the stem like land plants, algae directly absorb everything they need directly from the ocean.  Nutrients move from the ocean directly into lamina where it feeds the algae.  One major function land plants and algae have in common though is both harvest light using photosynthesis to produce sugar for energy.

All kinds of algae grow throughout the ocean, the largest and most interesting grow in the tidal zone.  These are distributed by elevation within or near the tidal zone.  Some species are located just above the tidal zone gaining nutrients from wave spray or splash.  Other species only like to be covered with with water for a short time each day so are in the highest portion of the tidal zone.  Others like weak waves and others very strong waves.  Each has their specific preference of conditions.  The largest are the furthest out from shore.  Bull Kelp, for example, can grow in water 100 feet deep with their highest lamina floating on the surface.  Kelp grows with amazing speeds of up to 20 inches in one day during the summer.
An underwater kelp forest.
The following video is great, showing how seaweed is harvested and the type of environment it is typically found it.  I have spent a decent amount of time in tidal areas like this and they are truly amazing places.  Typically, places like these are only accessible during low tide.  A few locations where deeper water algae grow may only be accessible during the lowest low tides which only happen a few days a month or a few days a year.  The waves, ocean, rocks, and great abundance of sea life in these areas is both beautiful and amazing.  At the same time these areas are extremely dangerous and only highly skilled and informed people can experience these areas on a relatively safe basis.  I say relatively because the constantly pounding waves, the rocks, and currents can be quite unpredictable, even to the most experienced.  Larch Hanson, the person harvesting the seaweed, is amazing at how he handles this dangerous environment, making it appear quite easy.

The Perennial Plate Episode 76: Seaweed Man from Daniel Klein on Vimeo.

Seaweed is truly remarkable for the number of things it can be used for.  Of course, most people know that sushi is wrapped in seaweed, specifically Porphyra.  Seaweed salads available in Japanese restaurants are typically made from Wakame.  Agar and other gelatinous materials are also produced from a variety of different alga.  It is also an excellent source of many different nutrients that are not typically present in other foods, but especially iodine.  This great diversity of available nutrients also makes it an excellent organic fertilizer.  Research is also being done on how to efficiently use seaweed to produce bio-fuels.  This all makes for a booming but relatively small seaweed agricultural industry that is still in its infancy having only started about 50 or so years ago.

More information on seaweed: Maine Seaweed: the Seaweed Man

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