Freshwater Biodiversity in India’s "Hottest Hotspot" in Peril

Shaji C P
Thursday, December 8, 2011

The rivers and wetlands of the Western Ghats support 174 species of dragonflies.
The rivers and wetlands of the Western Ghats support 174 species of dragonflies.
K.A. Subramanian

India’s Western "Ghats," which means "river landing stairs" in Hindi, is a mountain range from which numerous rivers and streams flow. These waterways provide sustenance for the moist and fertile lands that surround them. The rivers are also home to diverse fish species, many of which are found only in these rivers. The Western Ghats is the world’s most heavily populated Biodiversity Hotspot, and its rivers provide approximately 400 million people with drinking and irrigation water, and electricity generated through hydropower.

A recent IUCN “Red List” publication on freshwater biodiversity in the Western Ghats describes the crisis of biodiversity loss in the region. The assessment confirms that the river-rich Western Ghats is a globally significant center of biodiversity warranting urgent conservation strategies.

The Western Ghats run for 1,600 km parallel to the west coast of India and are divided into eight riverine regimes. From a biodiversity point of view, the Western Ghats is one of the eight “hottest hotspots” of the world’s 34 biodiversity hotspots. While the earliest dams were built downstream for irrigation, hydropower dams started devouring the upper forested catchments later on. Flows have been diverted and beautiful waterfalls, like the Jog, reduced to trickles. Dams upstream have impacted downstream water needs, fishing livelihoods, ecological functions, and led to deep saline ingress in delta farmlands. Presently a number of controversial dams – including the Gundia, Athirappilly, Pooyamkutty, Kalu and Shai, Dandeli and others ­– are at different stages in the planning and approval process. They are also being opposed by peoples’ movements.

A faunal and floral analysis of the biogeographic zones underscores the richness of the life in this region. Approximately 175 species of amphibians (130 endemics) and 290 freshwater fishes (189 endemics) have been reported from these most ancient mountains of the world. Of the 212 freshwater molluscs reported from India, 77 are found in the Western Ghats. The rivers and wetlands of the Western Ghats support 174 species of dragonflies, with 69 endemics. Roughly 608 aquatic plant species are reported from this eco-region.

Most of the Western Ghats streams have torrential flows in the upper catchments. Almost all the torrential streams at an altitude of 1500-2000m harbor several species of aquatic insects in their specialized microhabitats. Their life cycles get disrupted when these niches are submerged by dams. The food spectrum of several fishes consists of aquatic insects and their larvae. Alteration of flows due to dams in turn changes the diversity and density of aquatic insects, directly impacting fish populations and leading to disruption of entire ecosystems.

The IUCN report affirms that dams and diversions are the major impediments altering the river hydrology, consequently changing the habitat and making it less suitable for the survival of many specialized life forms. A study on dams in the region reveals a staggering 871 dams constructed by the year 2000, including 13 mega-dams and 34 large dams, which have submerged substantial riparian zones and prime evergreen forests.

Mining and quarrying have boomed in the Western Ghats during the past two decades, which is another menace to biodiversity. Water quality has changed considerably and large-scale sediment deposition has prevented the algal growth in the streams near the mines, disrupting the entire web of life. IUCN estimates that 6% of fishes, 5% of molluscs and 4% of plants are threatened due to mining and energy production.

In addition, residential and commercial developments, agriculture and aquaculture, and invasive alien species play a significant role in the depletion of the biodiversity of aquatic ecosystems of the Western Ghats.

The IUCN Red List further reveals that 12 freshwater fishes, 6 molluscs and 4 dragonflies are critically endangered and 53 species of freshwater fishes and 4 molluscs are endangered. An urgent policy and legal level intervention and awareness campaign are necessary to save the rivers and conserve riverine biodiversity in this important region.

IUCN puts forward some suggestions that are crucial for the very survival of biodiversity in the long run. Several species in the region are poorly documented due to lack of expertise and scarcity of information. The taxonomic inventories and monitoring of river systems deserves a high priority in the conservation agenda. The compilers of the Red List also recommend habitat restoration involving pesticide control, preservation of unique habitats like Myristica swamps, prevention of flow modifications, etc. which are apt in the present scenario. The study recommends to avoid large dams where unacceptable impacts to freshwater species are predicted.

One strong, novel and feasible recommendation is the prioritization of the Key Biodiversity Areas with the involvement of local communities to address the conservation issues based on the outcome of the Red List 2011. These areas are proposed to legally ensure the conservation of diversity while catering to the needs of stakeholders.  Establishing Key Biodiversity Areas with appropriate management plans and regulatory mechanisms seems to be a promising approach to curb the onslaught of dams and restore aquatic ecosystems.

The rivers in this “hottest of hotspots” are struggling to reach the seas. Aquatic species are facing habitat fragmentation and degradation from dams and other threats, often disappearing even before they have been recorded. More dams are in the pipeline. Ecological restoration of the remaining river catchments with due legal protection, and reviving flows in already dammed rivers, is urgently needed to preserve the remaining biodiversity of Western Ghats rivers.

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