Seaweed, What Are They And Their Benefits

There are over 12,000 species of seaweed, with researchers now suggesting  that between 50 and 70% of the Earth's oxygen comes out of the oceans, from seaweed species such as kelp, phytoplankton and algal plankton. I truly find that incredible, that's more than our forests and rainforests can produce by far!

Did you know that the Western Australia coasts alone are home to around 1,000 species of seaweed, and around 240 species known to be found in southern Australian waters.

The history of seaweed and it's uses goes back thousands of years, with written evidence dating back at least 1500 years from Japan where it has been used for food, and medicinal purposes. But it is not only the Japanese that have known the benefits of this amazing group! Various European countries, Indigenous Australians, the Philippines and more have all long known about these beautiful sea dwellers and gathered them for various purposes, but, as with most things this knowledge has faded and dwindled and is only in recent years being relearned.

What are seaweed? 

Seaweed is a very broad term that encompasses many species of marine plants and algae and are broken down into three groups, that all range hugely in size, shape and colour. Seaweed are a group of macro-algae that are believed to have existed for around a BILLION years! With the oldest seaweed fossil being that of a Proterocladus antiquus (a green seaweed varitey found in China).

Seaweed are plant-like organisms but are definitely not plants! They do not have a stem or roots, nor do they have flowers, seeds or leaves, and therefore, are not plants but algae.

Seaweed don't have roots, instead they have a 'holdfast' which anchors them to rocks etc to keep them from drifting away, it is not designed to absorb nutrients.

Following this holdfast is the stipe, which is essentially a stalk connecting the holdfast to the blade/leaf like structure above. Most will also have one or several gas bladders/floats, this ensures they stay closer to the surface for photosynthesis purposes.

The three groups of seaweed are browns, reds and greens.

Green seaweeds were the first group to appear around a billion years ago, and contain chlorophyll, which as most know, is the pigment responsible for photosynthesis. They tend to prefer temperate and tropical waters along rocky shorelines and tide pools where light can be easily accessed.

Red seaweeds (rhodophyta) appeared about 500 million years later, they can be anything from red to purple, light pink, even almost black, and contain phycoerythrin  and phycocyanin  pigments. They are the largest group of algae containing more species  than the greens and browns combined with over 2400 species worldwide!

Although generally found in shallow waters they can survive in deep waters and low-light situations. This is due to the phycoerythrin which reflects red light and absorbs the blue. Because blue light penetrates deeper this is what allows the red seaweeds access to those deeper waters.

Nori is one important seaweed! It is eaten worldwide and particularly Japan as its high in vitamins and protein content.

Have you ever wondered what carrageenan is on your food packets? Well it's a thickener/emulsifier and can be used to preserve food and drinks. It is brought to us courtesy of red seaweed, specifically, Chondrus crispus.

Brown seaweeds, or Phaeophyta (Phaeo meaning dark or dusky, and Phyton meaning plant) were the last group to emerge but they are no less spectacular! They are usually found in temperate and artic waters, the brown contain an extra pigment caled fucoxanthin, which is repponsibe for that browner colouring as it generally masks the green pigmentations. This means they tend to be 'browner' in colour; yellow-brown, olive greens, various shades of brown and some are almost black. Their cell walls have two layers, their inner layer provides strength, whereas their outer layer is mostly algin, which when wet, makes the seaweed jelly-like, but when dry the seaweed becomes brittle.

There is a fantastic section in Where The Wild Things Grow By David Hamilton describing the different varieties that is absolutely worth the read! Although I will take this opportunity to note, it is highly important you know what type of seaweed it is you're eating and where it is from as not all seaweed is edible! Some are lethal or are poisonous causing digestive issues. Seaweeds absorb toxins from polluted water, and consuming these can cause major issues, others contain harmful acids, inorganic arsenic, or iodine which can be extremely harmful in large quantities. Whilst others can cause dermatitis and burning lesions.

Also head over to Spotify and listen to Alie Ward's Ologies about the amazing world of seaweed!

    

Although from water, seaweed has many benefits on land, including food both for humans and livestock, and being used in medicines and pharamcuticals. Seaweed is found in or used for:

. Wound dressings

. Dental moulds

. Adhesives

. Dyes and textiles

. Biomedicines

. Dieting pills

. Toothpaste

And so so much more.

Seaweed of course has many uses in our gardens, it can boost soil health, act as a fertiliser and feed essential micro-organisms. Some seaweeds also act as plant growth regulators aka, hormones. The most commonly known ways are brought to us by Seasol; a concentrated seaweed tonic designed to boost the health and pest resistance of our plants and Seamungus; which is a plant and soil conditioner combining seaweed and many other goodies to help protect and boost our plants and soils. These companies have taken our seaweedy friends and sent them through various processes making it easier for us to use and our plants to access, because, lets face it, not all of us like trekking down to the beach with a bucket. (Also, if you do, check with the local councils regarding limitations and foraging regulations).

I know we've touched on the benefits of these products for your garden in various other posts but it had to be done again as it's very important!

Seasol uses Bull Kelp; Durvillaea potatorum, and Knotted Kelp; Ascophyllum nodosum and turns them into a liquid extract. It contains nutrients and trace elements, along with alginic acid and various other bioactive compounds. It is not a feriliser however, due to the low levels of nitrogen, phosphorrus and potassium.

Seamungus uses Bull Kelp thats washed ashore, rather than harvesting, which ensures Neutrogs more sustainable approach to their products. The seaweed contains natural stimulants that aid plants in ther battle to survive the elements and bugs and diseases.

Eco-seaweed is a highly concerntrated product, where a little quite literally goes a long way. Made from Ascophyllum nodosum, more commonly known as Knotted Kelp. Eco-seaweed is 100% certified organic and contains over 60 vital nutrients, it's packed full of goodness!

Seaweed plays a vital role in boosting your plants immune system, think of it like a vitamin supplement for us, the stronger our immune system is the less likely we are to get viruses and bacterial infections, same with plants, they find it easier to fend off bugs and diseases that may otherwise cause irreversible harm.

Seaweed are incredible organisms which we have barely scratched the surface of and will absolutely cover in more later down the track, but for now, appreciate all those wonderful seaweeds that sacrifice themselves for your garden, and help our planet thrive.