What Do You Know About Marine Algae?

Our lives depend on algae. Without these marine plants, there would be a collapse of aquatic ecosystems, meaning no seafood for our plates. Algae are primary producers at the base of aquatic food webs, vital for the health and vitality of marine organisms and ecosystems. Furthermore, in evolutionary terms, all land plants derived from a class of freshwater green algae. It is calculated that roughly 50% of the oxygen produced comes from these slippery organisms. Not only do we need algae to eat and breathe, algae could also potentially provide us with a form of green energy, helping us to deviate away from fossil fuels. Sustainable biofuel production is just one way algal may provide us with fuel thanks to its photosynthetic abilities. Not forgetting to mention that the pharmaceutical potential of algae too, these wonder organisms may even hold the key to treating deadly diseases like cancers and AIDs.

These marvellous organisms that float around our oceans are often forgotten, overtaken by the sharks, whales and dolphins. Why not try and get acquainted with them below?

The Chlorophyta (Green Algae)

Green Algae
Photo Credit: http://www.seealgae.com

Firstly, this is the type of algae you probably associate with the ocean – the green stuff. Green algae can be classified in two ways; in the broad sense as Chlorophyta having over 7,000 species, or under one clade of Viridiplantae with just over 4,000 species. The green algae you tend to find in marine habitats are chlorophytes, whereas those found in freshwater environments are charophytes. Beta-carotene is a really useful pigment found in green algaes, which can be used in food colourings and may even hold a cure for some cancers. Some really cool species of chlorophyta include Mermaid’s wine glass (Acetabularia crenulata), Sea grapes (Caulerpa racemosa) and the Three finger leaf alga (Halimeda incrassate).

The Phaeophyta (Brown Algae)


Brown Algae
Photo Credit: Green Light Images


Here’s the stuff you commonly see on the beach and around marinas across the UK. For me, the coolest brown algae is kelp. If you’re an avid viewer of nature documentaries, you’ve probably seen huge kelp forests. These underwater forests are incredibly important, hugely dynamic and productive ecosystems. Kelps can grow up to 18 inches a day, which is just mindboggling. Roughly 2000 species of brown algae are currently known. Another order, Fucales, are commonly found along rocky shores within intertidal zones. Usages for phaeophyta include edible seaweed as well as the extraction of alginic acid for food thickening agents. There are some inventive names for brown algae too – Bladders wrack (Fucus vesiculosus) and Oarweed (Laminaria digitata) being my personal favourites.

The Rhodophyta (Red Algae)


Red Algae
Photo Credit: Peter Southwood 2012

By far the prettiest of the bunch. Phycoerythrin and phycocyanin are the two pigments causing the red colouration of rhodophyta, by masking their other pigments, including chlorophyll-a. These corals have a number of commercial uses, including animal feed, with over 500,000 tonnes being harvested every year. Coralline algae – an important group belonging to the rhodophyta – have even been utilised in bone-replacement therapies! These rhodophyta  can be integral for coral reef formation as they secrete a calcium carbonate, much like corals do. Despite all the red algae’s being a wonder to look at, the geliriums take the prize for me.

So there you have it, a brief introduction to the three major phylums of marine algae. Next time you’re sauntering along the beach and notice a mound of green and brown foliage (maybe even some red if you’re lucky), don’t think of how grotesque and slimy it looks, remember how integral it is to all of our lives.


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