New red seaweed species discovered on Indian coasts

Marine botanists have discovered two new species of red seaweed from the coasts of Tamil Nadu, Gujarat, and Daman and Diu1. The red seaweed species are economically important because they contain carrageenan, an important biomolecule that is used widely in the food industry, the researchers say.

They say that mixing minute amounts of such red seaweeds in animal fodder has been shown to substantially reduce methane production in cattle.

Methane is an important greenhouse gas that contributes to global warming. “Reducing its production in the guts of cattle might be an important step towards mitigating climate change,” says marine botanist Felix Bast from the Central University of Punjab.

The discovery also opens up new opportunities for the commercial cultivation of the seaweeds that could support the livelihood of coastal communities in India, Bast told Nature India.

Seaweeds, also known as marine algae, come predominantly in three colours: red, green and brown. They grow abundantly along the coastline of India.

During a trip to assess the diversity of red seaweeds, Bast and his colleague Pushpendu Kundu collected samples from various locations along the south and west coast of India. They noticed that some of their collected specimens were very distinct from any known red seaweed species.

Analysing the structural features and specific molecular markers of the odd seaweed specimens, the researchers identified two new species. One of the species, with rough (bullate) or blister-like features, was named Hypnea bullata while the other was named as Hypnea indica. “H. indica has a spiral branching pattern with fork-like tips, and cells in the main axis surrounded with a group of rectangular cells,” says Bast. However, H. bullata has a unilateral (one side only) branching pattern.

The red seaweed species were also found to contain calcareous (calcium-based materials) deposits. “Such deposits could dissolve in acidic seawater and degenerate tissues, making the seaweeds vulnerable to the effects of ocean acidification,” Bast explains.

The red seaweeds could also be used as an indicator of ocean acidification, a phenomenon in which excess atmospheric carbon dioxide dissolves in seawater, turning it acidic, he adds.

Vaibhab A. Mantri, a marine biologist from the CSIR-Central Salt and Marine Chemicals Research Institute in Gujarat, says that the discovery of the new red seaweed species is significant since such seaweeds influence the marine ecosystems by providing shelter, diet and breeding grounds for various marine organisms.

The red seaweeds contain carrageenan, a polysaccharide that, in experiments, has shown antiviral, antibacterial and other medicinal properties including an inhibitory effect against the novel coronavirus, says Mantri, who is not involved in this research. He warns, however, that such properties need to be critically assessed in the near future.