PANAJI
The Mhadei watershed has emerged as one of the richest amphibian habitats in Goa, with the Madhei river-Satrem tributary watershed recording 19 amphibian species -- the highest species richness among the 12 watersheds surveyed in a new Goa University study.
The study, published in the Journal of Threatened Taxa, last month, surveyed 102 sites spread across 12 watershed zones in Goa’s Western Ghats and recorded 22 amphibian species, including eight Western Ghats endemics.
The findings could add fresh scientific weight to the ecological concerns surrounding Goa’s long-running battle against diversion of the Mhadei river by Karnataka. The documentation of high amphibian richness and the sensitivity of these communities to habitat and microclimatic changes underscores the ecological significance of the Mhadei landscape. The Madhei river-Satrem tributary watershed, identified as W3 in the study, recorded 19 species, ahead of the other watersheds surveyed. The researchers found that watersheds with intermediate canopy cover of around 80-95 per cent and deeper leaf litter supported greater amphibian diversity, highlighting the importance of the forest floor and microhabitat conditions in sustaining amphibian populations.
The findings are particularly significant for the Mhadei landscape, where forest streams and their surrounding habitats provide critical conditions for amphibians. The study found that leaf litter depth was the strongest environmental factor associated with amphibian alpha diversity. Species richness showed a positive correlation with leaf litter depth and humidity, while it declined with increasing temperature.
The researchers observed that species richness across the 12 watersheds ranged from nine to 19 species, with the Madhei-Satrem tributary registering the highest figure. The study found that the richest watersheds generally combined intermediate canopy cover with deeper leaf litter, creating favourable conditions at the forest-floor interface. The researchers said their findings “highlight the value of mid-successional forest patches for conserving anuran biodiversity amidst ongoing habitat alteration in this global biodiversity hotspot.” The study also cautions that complete canopy closure does not necessarily translate into better conditions for amphibians. According to the researchers, dense canopy can contribute to litter compression and higher temperatures, potentially reducing habitat suitability.
With climate change and habitat fragmentation placing increasing pressure on Western Ghats ecosystems, the researchers have called for the preservation of undisturbed leaf-litter layers and structurally diverse forest habitats, particularly around tropical montane streams.
The study covered 1,335.95 sq km of the Western Ghats region of Goa, including the Mhadei Wildlife Sanctuary, Bhagwan Mahavir Wildlife Sanctuary, Mollem National Park, Netravali Wildlife Sanctuary and Cotigao Wildlife Sanctuary.
