Algologies: 635+ Species and Counting

A rock pool ecosystem (June 2021) (Photo: Anna Dumitriu)

Seaweed identification is hard! I have been exploring the rock pools at the Undercliff and the more I look, the more diversity I see. I am still nowhere close to being able to identify many species without hours of research though, in fact what is surprising is just how overlooked these life forms are. I’ve been searching through Seaweed Collections Online, which seems to be the best resource but most of the images are of dried seaweeds from collections and these look so hugely different from the living or recently washed up examples I find.

Red coloured Coralina officinalis (Coral Weed) in a rock pool (Photo: Anna Dumitriu)

There is a lovely set of dried seaweed images from the Booth Museum in Brighton which holds some of Mary Philadelphia Merrifield’s collection. Merrifield was a pioneering Victorian seaweed collector and botanist (as well as art and fashion historian) based in Brighton. I expected to find all the species I’ve been finding in her collections but I’m not so sure. They all look so different. When I think I’ve identified one I search for it on the web, only to find it doesn’t have even a wikipedia page. I can’t imagine this happening with bacteria (an area I am much more familiar with) which are so much more studied.

I want to know why seaweed are not so well studied. Maybe it’s because they aren’t usually out to kill us like a small but infamous percentage of bacteria. Or maybe it’s because seaweed study is actually difficult.

Coralina officinalis (Coral Weed) skeleton attached to an anatomical heart-shaped rock on a background of Ulva intestinalis (Gutweed Chlorophyta) and Fucus vesticulosus (Bladderwrack) (June 2021) (Photo: Anna Dumitriu)

I learned that algae are not a ‘natural group’. Red and green algae are related to higher plants, but brown algae are not. These brown seaweeds (including wracks and kelps) are more related to diatoms and not plants at all. British seaweed is very diverse and apparently one of the richest seaweed ecosystems in the world. Seaweeds of Britain and Ireland states there are more than 635 species of seaweed, but only 238 of which are included in that book (the most comprehensive guide I’ve managed to find).

My well thumbed and slightly damp copy of “Seaweeds of Britain and Ireland: Second Edition”

They are not studied extensively so far through genomics yet, but there has been some interesting work done on economically important species. There are also moves afoot to use synthetic biology to use microalgae as biofuels and I cannot help but think there is huge untapped potential here for biohackers or kitchen/garage/citizen scientists to explore more.

What is incredible to me is how different these seaweeds look at different times of the day. I’ve tried to name the species as best I can here but if I’ve made a mistake and you know better I would love to hear from you. (via my contact form here).

Fucus vesticulosus (Bladderwrack) (Photo: Anna Dumitriu)

The Bladderwrack (above) – which is not a plant, -is very tolerant to drying out so it seems to live highest up the beach on the chalky rock pools. You can see in this picture just how different it looks in the water, compared to in the sun.

Ulva intestinalis (Gutweed Chlorophyta) (Photo: Anna Dumitriu)

Ulva intestinalis (Gutweed Chlorophyta) is the green seaweed which covers the rocks and breakwaters of the Undercliff like a soft green (somewhat fly infected) carpet has a faint smell of truffle produced by a chemical called dimethyl sulphide. This chemical is of critical importance for regulating climate by controlling cloud formation and most of it comes from seaweeds!

I think this is also Ulva intestinalis (Gutweed Chlorophyta) grows from ropes in the inner harbour at Brighton Marina (Photo: Anna Dumitriu)

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