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Dr. Suchandra Dutta

Very rare species of mangroves rediscovered after 63 years

Dr. Suchandra Dutta

A mangrove species, believed to be extinct from city forests, has been documented across Gorai and Charkop mangroves for the first time in 63 years. The last documentation of this ‘very rare’ species – Lumnitzera racemosa – was in 1957 from Mumbai, according to Mangrove Cell.

The details were revealed in a report ‘Status of Mumbai’s Mangrove’s’, prepared and submitted to the state mangrove cell, by Suchandra Dutta from the department of botany, RD and SH National College, Bandra.

“We found less than 10 shrubs of the Lumnitzera racemosa towards the northwestern suburbs of Mumbai,” said Dutta, principal investigator of the project.

Mangrove Cell also released location-wise sapling plantation data for the Konkan coast from 2015 to 2020 with survival rate ranging from 75% to 80%. The mangrove plantations were done over 1,480 hectares (ha) along the west coast including Mumbai at a cost of ₹40.36 crores over five years. “With 20 lakh saplings in our nursery, post-monsoon plantations over 200 ha has been planned this year,” said Virendra Tiwari, additional principal chief conservator of forest (Mangrove Cell).

Researchers from the National College identified 13 species and 37 mangrove associates from Mumbai while studying 260 plant species belonging to 231 genera and 92 families across 17 locations. Mumbai has 6,600 ha of mangrove cover, about 90% of which are dominated by one species, Avicennia marina or the grey mangrove – a fruiting plant with dark green leaves. The remaining 10% is dominated by other species such as Acanthus ilicifolius, Ceriops tagal, Bruguiera cylindrica, and Aegiceras corniculatum. However, species such as Kandelia candel, Sonneratia caseolaris and Avicennia alba that were documented from Mumbai between 1905-1957 have gone missing. Lumnitzera racemosa was one of them until the latest rediscovery.

Though it is common across Ratnagiri and Sindhudurg districts, it was identified from Bandra and Thane by late Dr Arvind Untawale from National Institute of Oceanography (NIO) in 1957. N Vasudevan, former Mangrove Cell chief, said, “This is an important find as this is a locally threatened species and brings to the fore the unique biodiversity of Mumbai’s mangroves.”

Growing urbanisation and demand for development in the space-starved city had made mangrove forests a target for developers altering their ecosystem, the report said. “Dumping of construction waste, sewage discharge and encroachment are some of the issues behind the depleting cover,” said Dutta. “Mangroves across Bandra, Gorai, Dahisar, Lokhandwala and Mira Bhayander are facing these issues leading to ecosystem changes.”

The study also identified the differentiating characteristics among four species of Avicennia, and documented a fifth member (new taxa) as Avicennia marina forma pumila near Tarzan Lake, Charkop. “Distinguishing factors showed this was a dwarf tree having different leaf shape, apex, and fruit,” said Dutta. She is now working on a study to check whether Salavadora alii (a mangrove species discovered in 2016) is present in Mumbai.

The National College report recommended mangrove tourism (as developed along with the Thane flamingo sanctuary) be replicated across Bandra, Gorai, Mira Road, Virar, and biodiversity-rich water bodies at Nerul (Talawe wetlands), Charkop (Tarzan lake) and Lokhandwala lake. “Apart from establishing a mangrove information centre, locals can act as tourist guides, which help develop awareness and reduce further anthropogenic disturbances,” said Dutta.

Tiwari said all recommendations would be considered. “The small grants program by our Mangrove Foundation is being given for similar research with unique findings to help strengthen mangrove and marine ecosystem conservation efforts,” he said.

Source: Hindustantimes website

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