Algae is incredible

This week at college, we have been looking at aquatic plants and ponds in gardens. Aside from our aquatic plant ident, featuring some of the most challenging botanical names I’ve come across (Lysichiton camtschatcensis, I’m looking at you), we were also asked to research algae. Before I starting this research, I thought algae was just that scummy green stuff that grew on stagnant water. How wrong I was. Sure, it can be the scummy stuff collecting on top of a forgotten bucket of water like a horrible froth on an equally concerning flat white, but it’s also the kelp forests that bring an invaluable food source and habitat to marine organisms. Algae is incredibly diverse and so much more significant to the economy and ecology than I could have imagined. So if you’re ready, let’s dive into the algae, in all its forms.

So what is algae?

The term Alga (or the plural Algae) refers to a simple, non-flowering and often aquatic plant belonging to a large group that includes seaweeds and other single-cell forms. Algae is an informal term for a large polyphyletic group (meaning that they are grouped together not because they have a confirmed common ancestor, but because they display similar characteristics). Algae can range from unicellular microalgae to a large brown alga known as giant kelp, which can grow up to 50 metres long. It is believes that the term Alga (the Latin word for ‘seaweed’) derives from the Latin alliga, which means binding or entwining. However, there is no confirmed etymological source.

Alga differs from plants because they lack many of the distinct cell and tissues types found in tracheophytes, including the following:

  • Stomata
  • Xylem
  • Phloem
  • Phyllids
  • Roots

Additionally, some algae types use complex sexual reproduction that is not commonly found in the land plants with vascular systems.

There are three main types of algae:

  • Phaeophyceae (brown algae): these are multicellular algae, including many seaweeds found in colder waters. Phaeophyceae live in marine environments and are ecologically important as a food source and a habitat for marine wildlife. There are between 1,500 and 2,000 brown algae species around the world. There are two visible features that set this type of algae apart from other forms: their characteristic olive green to brown colour and their multicellular status. There are no organisms in the Phaeophyceae group that exist in single cell or colonies of cells.
  • Chlorophyta (green algae): This informal group consists of several photosynthetic alga species, including unicellular types, colonial types, macroscopic types and multicellular seaweeds. Overall, there are about 22,000 species of green algae, with many species existing as single cells. Chlorophyta are distinctive due to their vibrant green colour, as a result of their chloroplasts that contain chlorophyll. Microscopically, all green algae can be identified through their mitochondria and flat cristae. While brown algae are exclusively found in marine environments and red algae are found mostly in marine environments, green algae mainly live in freshwater. Finally, oth red and brown algae are sessile (meaning that they do not move), whereas green algae are motile (meaning that they can move).
  • Rhodophyta (red algae): This is one of the oldest groups of eukaryotic and it contains over 7,000 recognised species. Of these, 6,793 are multicellular marine algae, making red algae abundant in marine habitats, although a small percentage of species do exist in freshwater habitats. As with brown algae, one of the significant characteristics that sets red algae aside is its colour. Its name Rhodo is Latin for ‘rose’, making it an distinctive feature that likely led to the classification of red algae.

While colour, cellular and habitat differences are visible differentiators, scientifically, the photosynthetic pigments of each algae group is what characterises them:

PigmentsBrown algaeGreen algaeRed algae
Chlorophyll axxx
Chlorophyll b x 
Chlorophyll cx  
Chlorophyll d  x
Phycobilins  x
Algae’s life cycle

While some algae reproduce through sporic meiosis, all algae can grow and repair itself through cell division, or mitosis. Mitosis is a process of cell duplication, where one cell divides into two genetically identical daughter cells.  The chromosomes of the cell are copied and distributed equally between the two nuclei of the daughter cells.

Here is an overview of how cell division works, using the cell divison of chloroplasts as an example:

  1. Proteins assemble into bundles of filaments, creating a ring inside the chloroplast
  2. A second ring is formed on the outside of the chloroplast membrane
  3. This outer ring begins to apply pressure to the chloroplast
  4. A fourth ring is created on the outside, which them moves under the outer plastid ring, applying even more pressure
  5. The chloroplast completes division, separating into two daughter chloroplasts

This process is significant in algae, as this helps some species grow very quickly, as well as repair damaged tissue fast. For example, the giant kelp can grow as much as 30cm in one day.

The economic and ecological importance of algae

Algae in general have several uses, and are economically significant. Here are a few ways in which algae are used commercially:

  • Food

Algae is a source of fats, proteins, vitamins A, B, C and E, carbohydrates, iron, potassium, magnesium, calcium, manganese and zinc. This makes it an amazing food source and could potentially be used to help fight hunger.

  • Fertiliser

Due to the vitamins and minerals listed above, algae are often used as liquid fertilisers.

  • Binding agent

All brown algae contain alginic acid in their cell walls, which is commercially extracted and used to thicken foods, among other things, including lithium-ion batteries.

  • Biological indicator

Due to their sensitivity to changes in environments, changes in their pigments are often used as an indicator in water pollution testing.

  • Pisciculture

Alginic acid can also be used in aquaculture, as it can help to strengthen the immune system of some fish, and this can increase yield and survival rate of fish.

  • Fodder

Algae can be used to feed livestock such as cattle and chickens. In certain regions, it is used as a grain for this same purpose.

Furthermore, algae is ecologically important, as it supports wildlife and helps to fight climate change:

  • Brown and red algae have adapted to a series of marine environments, including the tidal splash zone, rock pools and relatively deep shoreline waters. They provide habitats for a wide range of animals, as well as being edible. In freshwater environments, green algae and some red algae can serve these purposes too.
  • Importantly, algae fix a significant portion of carbon dioxide in the world through photosynthesis, with some scientists claiming that algae are the source of more than half of the world’s oxygen through photosynthesis.

While this may sound beneficial on the economic and ecological front, there are some serious issues associated with algae:

Toxic algal blooms: Some algae species produce toxic blooms which poison filter feeding shellfish, which go on to poison their predators – mussels and clams. These shellfish in turn become poisonous to any animals, including humans, that consume them. This leads to fatal outbreaks of shellfish toxicity that kill people, marine mammals, birds, fish and invertebrates. These toxic blooms are made by mostly red algae, which is where the name ‘red tides’ comes from, to describe these deadly blooms.

Dead zones: An excess of nutrients can enter the ocean through agricultural chemicals and human or animal waste. This then leads to an excess of algae in marine habitats. As they die and decompose, the ocean is depleted of oxygen, making it unlivable. Wired Science states that there are 400 major dead zones in oceans around the world, with one covering over 18,000 squared kilometers.

In aquaculture: Algae can pose issues and threats to wildlife, as they can deplete the water of oxygen, while also immobilizing corals, for example.

By reducing the damaging chemicals that enter the ocean, managing algae populations and improving detection of ‘red tides’, we can benefit from the immense economic and ecological advantages of algae, safely.

There’s no doubt – I have only just scratched the surface when it comes to the beauty and importance of algae. However, I hope this brief synopsis has made you think a little differently about this interesting little corner of the plant kingdom. I know the second I’m back in Muizenberg in Cape Town, I’ll be jumping right in the ocean to get a closer look at the beautiful kelp forests. For now, I’ll work on getting over my fear of sharks. Wish me luck!


Anwar, S., 2020. What is the Economic Importance of Algae?. [online] Available at: <,provide%20oxygen%20to%20the%20water&gt; [Accessed 27 January 2021].

Keim, B., 2020. Ocean Dead Zones May Be Worse Than Thought. [online] Wired. Available at: <; [Accessed 27 January 2021].

Mackay, J., 1836. “Flora hibernica”, comprising the flowering plants, ferns, characeae, musci, hepaticae, lichenes and algae of Ireland, arranged, according to the natural system, with a synopsis of the genera according to the Linnaean system, by James Townsend Mackay ... Dublin: W. Curry Jun.

Pediaa.Com. 2019. What is the Difference Between Red Brown and Green Algae – Pediaa.Com. [online] Available at: <; [Accessed 27 January 2021].

Tidal Film, 2018. On that note… if you haven’t gone for a dive in False Bay yet, we can DEFINITELY recommend it! 🐟 [image] Available at: <> [Accessed 27 January 2021].

Willson, J., 2017. Harmful Effects of Algae. [online] Sciencing. Available at: <; [Accessed 27 January 2021].

Gardening Journal – Entry 6

Tuesday 22 September 2020

Today was another busy day spent hedge cutting down by the river Thames. We worked on cutting back the Trachelospermum jasminoides, which is attached to a wire frame above beds of lavender.

We used the long-arm hedgecutter to cut the jasmine back to the bed size beneath it, keeping the sides well trimmed. Unfortunately the T. jasminoides above two of the beds was in a poor stte, with a lot of yellowing leaves and plenty of dead branches. These were more tricky to work with, as there was less wiggle room when it came to finding the ‘lowest point’ to cut into. Finally, we cut the tops of the jasmine, nonetheless, as it was trained to climb towards an upwards slope, ever bed became more and more challenging to cut, without the use of a platform ladder.

Initially, I used the harness as it is meant to help take some of the weight off the machine and make it easier to manoeuvre. I did not find this to be the case, as the harness was too big for me and did not fit on my back. Instead, it pushed my head forwards when I was working and made it difficult to looking up a the plants without straining my neck. This is another in several examples of manual handling aids causing more issues. Eventually, I used the machine without the harness and – while this made it a lot tougher on my arms and shoulders – it helped my keep the lines (and my neck) straight.

We worked on these hedges for four hours straight and by the time we had finished, we were absolutely shattered. Bear in mind, this included lugging the machinery, cones, green bags, 150m of hose and the rest up and down two flights of stairs; hello manual handling hazard! Just when our arms were about to give out, we lugged more wheelbarrows about to cut the lavender under the jasmine. The lavender is on its last legs – and quite leggy at that – so we gave it a hard prune back. It usually isn’t advised to cut back into the woody part of the plant, however, it can be a way of extending its lifespan, when left unpruned for years.

This week so far has been very hard on our bodies and I’m full of aches and pains again, like I was when I first transitioned into this job! I’m not sure how a whole day of practicals at college is going to go tomorrow but I can’t wait to see our class and tutor again and work on a different site. In the meantime, keep my arms and shoulders in your prayers.

Gardening Journal – Entry 5

Monday 21 September 2020

After a lovely but busy weekend, waking up this morning was a bit of a struggle and I feel like the fogginess of the morning stuck with me throughout the day.

Today, we kicked off the week with a litter round. Seeing as the country feels days from a huge lockdown, people went ham with the public drinking last weekend and we collected two full bags of rubbish.

After our first break of the day, we went back to Greyfriars to finish cutting the low Euonymus japonicus hedge. I also worked on three Ilex topiary balls and managed not to make them look like eggs on their sides like last time!

This afternoon, we spent some time cutting six Taxus baccata hedges. When cutting Taxus, you tend to cut at an angle, creating a wider base and a tapered top. This allows more sunlight to reach the base of the hedge, encouraging vigorous growth and promoting overall health for the hedge. As the hedges were almost as tall as me, Laurence worked on the tops of the hedges using the long-arm hedgecutter and I cut the sides with the normal hedgecutter.

I’m starting to feel more confident cutting different species and heights of hedges and if the feeling in my arms right now is anything to go by, I’m going to be JACKED by the end of this apprenticeship.

Gardening Journal – Entry 4

Friday 18 September 2020

Fridays are always busy, even though I only work until 12:30pm. This is because on Friday I go to the launderette to do our washing and catch up with any work I’ve missed during the week. 

Today we had a discussion about COVID concerns for the team in the morning and then Laurence and I went on our litter round. Since our litter round was shortened a few months ago, it usually only takes about half an hour to complete. As such, we treated ourselves to a coffee before our tea break and looked through some of our plant idents. 

After tea, I worked with my supervisor on some of the raised lavender and Trachelospermum jasminoides beds. As we didn’t have much time, we worked on the lavender exclusively and will start cutting back the T. jasminoides next week. 

When left unpruned, lavender becomes leggy and woody and eventually, very little of the stems bear flowers. Usually, lavender has a lifespan of four to five years. In order to encourage the lavender to produce some new growth and extend its life, we cut back all the diseased, damaged and dead before pruning back to any new growth at the base, keeping any remaining stems to 5-10cm. Hopefully in a few months, we will start to see some fresh, new growth and we can wait a few more years before having to replace the plants. 

After I finished at work, I spent the afternoon wrapping up some of the assignments I didn’t have time to finish on Wednesday. This included my assignment on Health and Safety legislation and the costing of planting five different species of hedge. I particularly enjoyed working on the latter, as it was fun to work on a hypothetical gardening project.