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Tuesday, May 17, 2022

Growing human interference, declining rainfall threat to forest swamps of Western Ghats: Study

In recent decades, the swamps are facing existential threats mainly due to the growing human interference and expanding agriculture.

Written by Anjali Marar | Pune |
March 22, 2022 1:31:28 pm
Myristica swamps are seen in Karnataka’s Uttara Kannada district. ARI Photo.

Scientists from Pune have identified as many as 44 novel species of diatom—algae rich in oxygen generation and have single-walled silicon cell walls—from the Myristica swamps in the Uttara Kannada district of Karnataka.

The joint study by Karthick Balasubramanian from the Agharkar Research Institute (ARI) and Mital Thacker, a PhD student working at ARI and affiliated with Savitribai Phule Pune University (SPPU), was aimed at understanding the biological, physical and chemical assessment of these swamps with respect to the changing water quality.

They studied diatom diversity inside the Myristica swamps in the Uttara Kannada district and identified 91 diatom species from 17 sites. The study has been published in the journal Diversity.

“Finding 44 novel diatom species means nearly half of them are novel and endemic. But this finding points towards our limited knowledge and understanding of the diatom diversity from tropical countries like India,” said Mital Thacker.

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Myristica swamps are endemic to the Western Ghats but are now restricted to only small patches found in Southern Kerala, Northern Karnataka, Goa, and a single swamp in Maharashtra because of fast shrinking and fragmentation.

These swamps are water-saturated regions within which trees grow with pneumatophores or breathing roots and stilt roots in order to survive in a submerged condition. In recent years, several new species of butterflies, diatoms, frogs, and mushrooms have been identified from these swamps.

However, in recent decades, the swamps are facing existential threats mainly due to the growing human interference and expanding agriculture.

Thacker said these swamps are under tremendous pressure from human activities like gradual conversion of swamps to agriculture fields, and various anthropogenic interferences, such as diversion of swamp water towards irrigation to cultivate areca nut, and various developmental projects like construction of roads and check dams.

“Diversion of the swamp water can be fatal for these swamp-dwelling biodiversity, which has evolved to survive in perennially-flowing water bodies. The diatom assemblages, which are affected by the water chemistry, serve as powerful bioindicators in any aquatic system. A change in land use can lead to a drastic change in water chemistry, and depleting water quality will alter and threaten the associated diatom diversity,” she explained.

Myristica swamps are a unique aqua-ecosystem, and in order to survive, the region must receive an average annual rainfall of 3000 mm or above. What makes these among the most extreme habitats is their acidic nature, and the ability to thrive in high humic decomposition.

Besides human interference, Balasubramanian said climate change could heighten the threat to the swamp expanse. “These unique habitats are disappearing at an alarming rate. We are not only losing these ancient habitats and their associated biodiversity but unknowingly erasing the biological history that shaped the past,” said Balasubramanian from the Biodiversity and Paleobiology Group at ARI.

Of the 17 sites, rich species diversity was traced at a site identified as New Kathlekan, whereas at another site, Assoli, the species diversity was the least, according to the study supported by the Union Ministry of Earth Sciences as a part of the paleoclimate programme.

“Anthropogenic disturbances were low and agricultural impacts were less in areas with high species richness and diversity. Besides, sacred groves, religious and traditional conservation practices could be the reasons for fewer human disturbances. Species richness and diversity of diatoms can be used to evaluate pollution status across these swamps,” said Thacker.

They have proposed both an increased protection and a greater need for studying microorganisms growing in these swamps (the wetland ecosystem), which act as natural environment health indicators.

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