Context

Seaweeds help maintain ecological balance and need to be conserved.

About

What are Seaweeds?

• Seaweeds are the primitive, marine non-flowering marine algae without root, stem and leaves.
• They vary vastly in size, shape and colour.
• The seaweeds derive nutrition through photosynthesis of sunlight and nutrients present in seawater.
• They release oxygen through every part of their bodies. 
• It is used as an ingredient in preparing toothpaste, cosmetics and paints. 
• Conservation status: The conservation status of seaweeds is yet to be evaluated by the IUCN.

Why Seaweeds are important?

• Marine ecosystem

Seaweeds play a major role in marine ecosystems.

• Habitat: The thousands of species of this organism provide habitats for marine lifeforms and protect them from threats. 
• Underwater nurseries: Large seaweeds form dense underwater forests known as kelp forests, which act as underwater nurseries for fish, snails and sea urchins. The herbivorous marine animals also feed on its thallus. 
• Balancing the ecosystem: Some nutrients found in large waterbodies are toxic to the marine life and can even kill them. Seaweeds, found mostly in the intertidal region, in shallow and deep waters of the sea and also in estuaries and backwaters, absorb the excess nutrients and balance out the ecosystem.
• Supply organic nutrients: They also supply organic nutrients, which they are capable of producing, to other marine lifeforms.
• Trap dangeorus metals/mineral: These aqautic organisms heavily rely on iron for photosynthesis. When quantity of this mineral (iron) exceeds healthy levels and becomes dangerous to marine life, seaweeds trap it and prevent damage. Similarly, most heavy metals found in marine ecosystems are trapped and removed by seaweeds.
• Bio-indicator: They also act as a bio-indicator.

Agriculture and animal husbandry

• Fertilizers: The importance of seaweed in agriculture and animal husbandry is noteworthy. They can be used as fertilizers.
• Increase fish production: They can also be used to increase fish production.
• Cut on methane emission: Also, when livestock is fed with seaweed, methane emission from cattle may be reduced substantially.

Can they mitigate climate change?

• Seaweed has a significant role in mitigating climate change.
• By afforesting 9 percent of the ocean with seaweed, it is possible to sequester 53 billion tons of carbon dioxide annually.
• Hence, there is a proposal termed as ‘ocean afforestation’ for farming seaweed to remove carbon. 
• Additionally, they may be buried in beach dunes to combat beach erosion. 

Harmful Seaweeds However, some rare species of seaweed clash coral reefs and damage them severely. The exotic, invasive Kappaphycus alvarezii seaweed is posing a serious threat to the coral reefs. PepsiCo (an American multinational food, snack and beverage corporation)  have started smothering the coral reefs and slowly killing them. In 2005, a government order was issued restricting the cultivation of the exotic species only to the seawaters north of the Palk Bay and south of Thoothukudi coast. The forest department is carrying out manual removal of the seaweed annually since 2014 to protect the coral reefs.

What is harming seaweeds?

• Nutrient imbalancing: When waste from agriculture, industries, aquaculture and households are let into the ocean, it causes nutrient imbalance leading to algal blooming, the sign of marine chemical damage.
• Mechanical dredging: Mechanical dredging causes damage to the kelp forests formed by large seaweeds.
• Indiscriminate collection: Indiscriminate collection of seaweed also causes severe damage to the useful algaes. Fisher folk collect tonnes of seaweeds daily around the islands. And while doing so, they break the corals.