Indiscriminate collection of seaweeds severely damages the algae, which is critical for balancing marine ecosystems and plays a role in thwarting climate change. Seaweeds, the primitive, marine non-flowering marine algae without root, stem and leaves, play a major role in marine ecosystems, say the scientists in a study published by downtoearth organisation.
The thousands of species of this organism that vary vastly in size, shape and colour, provide habitats for marine lifeforms and protect them from threats. 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.
On their part, the seaweeds derive nutrition through photosynthesis of sunlight and nutrients present in seawater. They release oxygen through every part of their bodies. 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.
They also act as a bio-indicator. 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.
These aquatic organisms heavily rely on iron for photosynthesis. When the quantity of this mineral 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.
They also supply organic nutrients, which they are capable of producing, to other marine lifeforms. Seaweed has a significant role in mitigating climate change. By afforesting 9 per cent 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. The importance of seaweed in agriculture and animal husbandry is noteworthy. They can be used as fertilizers and to increase fish production. Also, when livestock is fed with seaweed, methane emission from cattle may be reduced substantially.
Additionally, they may be buried in beach dunes to combat beach erosion. It is used as an ingredient in preparing toothpaste, cosmetics and paints.
The southeast Indian state of Tamil Nadu has 1,076km coastline with the convergence of the Bay of Bengal, Arabian Sea and the Indian Ocean. The southern Gulf of Mannar’s rocky intertidal and lower intertidal regions maintain rich populations of several seaweed species.