Seaweed farms near the Indonesian island of Nusa Lembongan, southeast of Bali. Photo: courtesy sookut.com

Seaweed farms near the Indonesian island of Nusa Lembongan, southeast of Bali. Photo: courtesy sookut.com

kdropcapsaren Phillips writes for deeperblue.com that algae are the alveoli in the ocean lungs of our planet, vitally important to the health of the seas as home, food source, sanctuary and above all the source of over half the oxygen on this planet.

In coral seas there are two main kinds of flora – the microalgae that live within the coral and provide not only food for the fish, but color for the reef. Then there are the macroalgae, which include seaweed and can be either soft or hard – the soft is food, the hard is calcareous. Both work together to shape the seascape.

  • Reef Builder: Red algae such as Hydrolithon and Lithophyllum produce limestone, which cements together broken pieces of coral, holding the reef together when the storms come and providing a foundation for growth. Without this cement the corals would not be able to build up vertically.
  • Sandmaker: Crusty species of green algae like Halimeda create our sandy beaches. While coral debris and the skeletons of marine invertebrates like molluscs and sea urchins are found in sand, the biggest single contributors is broken up Halimeda.
  • Food Source: Algae, both fleshy and calciferous serve as food for vegetarian fish and invertebrates, forming the first link in the undersea food chain.

With more than half of the world’s populating living within 150km of a coastline, and with the cost of treating waste being so high, many emerging economies are discharging waste into the oceans untreated. Weed thrives in this kind of nutrient rich waste. Algae blooms and weed influxes in tourist destinations are unwelcome but what if the weed were being used to clean up the seas?

In a recent article for Blue Economy, Nicholas Paul, Principal Research Fellow at James Cook University, Townsville, Australia (Blue Economy), made the case for using weed to clean our oceans:

“They [seaweeds] are essentially miniature solar powered treatment plants whose products are valuable. Consider this: for every 100,000 tons of dried seaweed produced in Indonesia, this seaweed has removed from the coastal water: 500 tons of nitrogen; 50 tons of phosphorus; and 15,000 tons of carbon (which equals more than 50,000 tons of CO2 sequestered).”

He puts forward the idea of creating floating wastewater treatment plants of seaweed that “not only remove nutrients (the nitrogen and phosphorus) but also deal with carbon capture and ocean acidification.” It can form the basis of sustainable development in vulnerable coastal economies.

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