Ramachandra TV and Karthick B
Energy & Wetlands Research Group, Centre for Ecological Sciences, Indian Institute of Science
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Citation : Ramachandra T.V. and Karthick B., 2009. Research prospects in western Ghats stream ecology: Perspective from river Sharavathi, Pollution Research, 28(1):19-20.
The Western Ghats is one of the hottest hotspots of biodiversity (Myers, et al., 2000), with tremendous species richness and high levels of endemism. The region is a repository of biodiversity evident from sprawl of description of new species (Aravind, et al., 2004) in recent times. Western Ghats acts as watershed for the major peninsular rivers like Tapti, Krishna, Cauvery and plentiful of small rivers in the state of Gujarat, Maharastra, Goa, Karnataka, Tamilnadu and Kerala. Most of the west flowing rivers along with their terrestrial ecosystems plays a pivotal role in maintaining the ecological balance. Recent efforts confirm that these fresh water ecosystems are the treasure trove for the description of new species. River Sharavathi is one such river rises in Ambuthirtha in Shimoga district and joins in Arabian Sea at Honavar of Uttara Kannada district of Karnataka. Biodiversity exploration in this river ecosystem reveals a vast range of algae, micro and macro invertebrates, fishes, amphibians and an array of mammal and bird species. As of date, biological records reveal about 242 species of algae, 39 species of zooplankton, 37 genera of aquatic insects, 115 species of fishes and 35 species of amphibians.
The biological exploration of this river dates as early as 1958 for algae by Iyengar, (Randhawa, 1959) followed by Gandhi during 1959 to 1970. Iyengar laid the foundation of biological exploration with a description of 4 new species of green algae (Debarya jognsis, Zynemopsis saravatiensis, Zynemopsis jogensis, and Spirogyra jogensis). Subsequently Gandhi’s(1958, 1959a, 1960c, 1966 and 1970) meticulous work on taxonomy heralded further with description of 22 new species of diatoms (Ceratoneis jogensis, Cymbella rivularis, Cymbella sagarensis, Eunotia jogensis, Eunotia rivularis, Eunotia saravathense, Gomphonema sarvathense , Navicula jogensis, Neidium grandis, Neidium jogensis, Nitzschia pseudogracilis, Pinnularia mysorense, Pinnularia sagittata, Surirella capronioides, Gomphonema spiculoides, Gomphonema tenius , Navicula fridrrichii, Pinnularia balatoneis, Pinnularia pseudoluculenta, Synedra jogensis, Frustulia jogensis, Navicula subdapaliformis). This trend got major boost with recent work of Bhat and Jayaram (2004) describing a new fish species Batasio sharavathiensis and by Sreekantha et al. (2006) with a discovery of Schistura nagodiensis and Schistura sharavathiensis and Philautus neelanethrus sp. nov. (Gururaja et al., 2007). However there are many more species yet to be explored in other taxa too, and most of them are in the verge of extinction due to large scale rampant degradation due to unplanned development initiatives. This might prove detrimental to the sustainability of this ecologically fragile and a very sensitive hot spots of biodiversity.
Deforestation has impaired hydrological regimes. River flow regulation by dams (Linganamakki and Gerusoppa Dam) and non-point sources of pollution due to agricultural activities has imposed tremendous pressure on river biota. Due to large scale land-use changes in unregulated rivers and streams lacks natural hydrological regimes (Ramachandra, et al., 2004). The deleterious consequences of drainage basin misuse and forest clearance are evident throughout the region, resulting in increased runoff, sediment transport and changes in river flow. In essence, large scale changes in flow are an inevitable result of deforestation. The construction of dams to regulate the flow regime and to generate energy, appears more of short term gain options (Ramachandra, et al., 2007).
The NRDMS division, Ministry of Science and Technology, Government of India supported this work.