How seaweeds benefit us all

Seaweed is a commonly used term for a vast and complex genus of plants covering some 6000 species. The term refers to the large marine algae that grow in the shallow waters at the edge of the world’s oceans.

Seaweeds provide a natural habitat and a source of food for a huge range of marine animals and enhance the natural beauty of the shore and underwater landscape. They are hugely valuable to humankind as a food, an industrial raw material and increasingly as a highly active cosmeceutical ingredient.

Seaweeds are correctly classified as plants because they use photosynthesis to produce carbohydrates. They are simpler in their biology than land plants – getting the nutrients they require from the surrounding water with no need for roots or complex conducting tissues.

Some large seaweeds such as the kelps do have root-like parts called holdfasts, but these are only used as anchor points to attach the seaweed to the rock. Most seaweeds need to be attached to something in order to survive, and only a few will grow while drifting loose in the sea.

Three groups of seaweeds are recognised based on the colour of the plant – red, green or brown. Needing light to survive – seaweeds are found only in the relatively shallow parts of the oceans, which means around the shores at depths of up to 40 metres.

Here they occur in a wide variety of forms and sizes, from the large kelps that form forests on cooler coasts, to the hard “encrusting corallines” that are vitally important in building and cementing coral reefs in the tropics.

Some of the larger red seaweeds are extremely attractive and highly visible – others are small and inconspicuous, growing over the rocks at the water’s edge.

Sea weeds are actually not ‘weeds’ at all since they are essential and highly valuable to human life. Together with phytoplankton (microscopic floating plants) seaweeds form the basis of the food chain in the sea. Thousands of tiny sea animals feed on seaweeds and are then in turn eaten by larger animals, and so on through to fish and ultimately perhaps to man.

Seaweed extracts are incredibly widely used in modern life across thousands of everyday objects and foods from yoghurts and pet food to toothpaste, cosmetics and beer.

In the West, the seaweed industry is based mainly on the production of these extracts but in the East the emphasis is on seaweed cultivation for food. Vast seaweed farms are found in China, Japan and Asia and in Japan the farming of Nori or Porphyra is an industry worth billions. This crop and others like the brown seaweeds called “Wakame” and “Kombu” are regarded as delicacies and sold for high prices.

In recent times marine algae have become a huge focus for scientific research as the potential of the genus as a high protein nutrient and antioxidant has become apparent.

Read further information on marine algae

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