At Leclerc
. . . in Lannilis I saw a small book about algae (seaweed) in the supermarket’s book department. As I browsed through, I became increasingly interested and wanted to learn more about the green/brown mass that lies on our doorstep from Sandpiper Cottage by the Sea. Here in Plouguereau and on the coast of Finistére, algae (seaweed) is part of the cultural heritage and is still an important industry today. Earlier this year, I addressed the topic of algae in one of my blogs, entitled “The Power of Seaweed“. Today I’d like to tell you some basic facts of marine biology.
Oxygen producer and CO2 binder
What amazes me is that algae is an essential producer oxygen for our ecosystem. Algae was important in the emergence of the first life forms on Earth. Through photosynthesis, and absorption of CO2, algae released oxygen and thus contributed to changing the Earth’s atmosphere billions of years ago. Two thirds of atmospheric oxygen is derived from the photosynthesis of algae. This means that besides the rainforest, algae form the second “green lung” of our planet. Probably that’s why I feel so comfortable on the world’s shores; especially here in Brittany.
Algae not only produces oxygen, it also removing CO2 from the atmosphere and is therefore partly responsible for preventing global warming. So algae, a real “powerhouse” for our ecosystem.
Some algae develop a special symbiotic relationship with fungi called lichens and they benefit each other. The fungal component absorbs water and minerals and provide them to algae. The algae provides products of photosynthesis like glucose or sugar to the fungus. Lichens are always named after the fungus that forms the lichen, as it is usually this one that gives it the shape and structure.
Reproduction
There is also something amazing to report about sexual reproduction among algae. There are two varieties. Rapid asexuel reproduction without genetic diversity, meaning it duplicates itself. The 2nd one is sexual reproduction which results in algae which is more genetically adaptable to their environment. As you can imagine, the second version takes longer to find the right “partner”, considering the restless sea movement 🙂
Coastal zoning
Especially in the coastal area, the structure (zoning) is clearly visible on the feature image above. My illustration below (compiled from different sources) shows the structure in a simplified way. The images I took further below show algae in the area around Sandpiper Cottage by the Sea which correspond to the four different zones.
The Supralittoral zone is the splash/spray water zone where lichens can be found
The Mediolittoral zone is the tidal zone
The Infralittoral zone begins at the lower waterline, i.e. from the constantly submerged area of the coast
The Circalittoral zone begins where the light becomes too weak for light-loving organisms (such as seaweed) to thrive. I couldn’t take any images in that darkness.
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