Ecological Profile of Sharavathi River Basin
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Sahyadri Conservation Series 22 ECOLOGICAL PROFILE OF SHARAVATHI RIVER BASIN Ramachandra T V Subash Chandran M D Joshi N V Sreekantha Raushan Kumar Rajinikanth R Desai, S.R. Subhash Babu Western Ghats Task Force, Government of Karnataka Karnataka Biodiversity Board, Government of Karnataka The Ministry of Science and Technology, Government of India The Ministry of Environment and Forests, Government of India ENVIS Technical Report: 52 November 2012 Environmental Information System [ENVIS] Centre for Ecological Sciences, Indian Institute of Science, Bangalore - 560012, INDIA Web: http://ces.iisc.ernet.in/energy/ http://ces.iisc.ernet.in/biodiversity Email: [email protected], [email protected] ECOLOGICAL PROFILE OF SHARAVATHI RIVER BASIN Ramachandra T V Subash Chandran M D Joshi N V Sreekantha Raushan Kumar Rajinikanth R, Desai, S.R. Subhash Babu Western Ghats Task Force, Government of Karnataka Karnataka Biodiversity Board, Government of Karnataka The Ministry of Science and Technology, Government of India The Ministry of Environment and Forests, Government of India ENVIS Technical Report: 52 November 2012 Environmental Information System [ENVIS] Centre for Ecological Sciences, Indian Institute of Science, Bangalore - 560012, INDIA Web: http://ces.iisc.ernet.in/hpg/envis http://ces.iisc.ernet.in/energy/ http://ces.iisc.ernet.in/biodiversity Email: [email protected], [email protected] [email protected] ECOLOGICAL PROFILE OF SHARAVATHI RIVER BASIN Ramachandra T V Subash Chandran M D Joshi N V Sreekantha Raushan Kumar Rajinikanth R, Desai, S.R. Subhash Babu Content 1 Aquatic ecosystem 2 2 Water and sediment characterization 7 3 Phytoplankton diversity 38 4 Zooplankton 61 5 Freshwater fish diversity and fisheries 66 PUBLICATIONS 6 Developmental mode in white-nosed shrub frog Philautus cf . 91 leucorhinus 7 A New Frog Species from the Central Western Ghats of India,and Its Phylogenetic Position 8 Two New Fish Species of the Genus Schistura Mcclelland (Cypriniformes: Balitoridae) from Western Ghats, India 9 Fish diversity in relation to landscape and vegetation in central Western Ghats, India 10 Nestedness Pattern in Freshwater Fishes of Western Ghats: An Indication of Stream Islands Along Riverscapes 11 Bioenergy Status of Sharavathi River Basin, Western Ghats, India 12 Cumulative Environmental Impact Assessment 1 AQUATIC ECOSYSTEMS Freshwater river systems are among the most diverse and productive ecosystems in the world. Much of the biodiversity associated with the riverine landscapes is attributable to heterogeneity at the habitat scale. From a holistic landscape perspective, riverine habitats comprise running and standing waters, permanent and temporary waters, wetlands and groundwater (Ward, 1998). At the same time, the biodiversity of most microbial, plant, and animal groups of stream, lake, and wetland ecosystems is very poorly known (Wetzel, 2001). Human evolution exhibited repeated speciations from Australopithecus to Homo habilis, H. erectus, and H. sapiens; and from their hominoid ancestor to orangutans, gorillas, chimpanzees, and humans (Ayala and Ananias, 1996) and this event spanned approximately 4 million years. This emergence from a position of a social ape of the savannas to its present position of global dominance has been a key in the changes that already took place and those still happening world over. Such changes are the clever manipulation of the environment, deflecting energy from other parts of the natural food webs into the support of one species (Cox and Moore, 2000). Part of the success of the human species has been their ability to influence the hydrological cycle: storing water for drinking, growing food and driving industrial processes and harnessing its power to generate power and fight against natural hazards, such as floods and droughts (Acreman, 2001). Our overall activities and their side effects have shaped the natural resource base as human-modified ecosystems. Human interaction with the physical environment has increasingly transformed Earth- system processes (Dillehay and Kolata, 2004). Wherever human land use is located near sensitive natural areas, such as wetlands, it had significant impacts on biodiversity in such areas (Eppink et. al 2004). These ecosystems share a common set of traits including simplified food webs, landscape homogenization, and high nutrient and energy inputs. Ecosystem simplification is the ecological hallmark of humanity and the reason for our evolutionary success. However, the side effects of our profligacy and poor resource practice are now so pervasive as to threaten our future no less than that of biological diversity itself (Western, 2001). The magnitude of the resulting change is so large and so strongly linked to ecosystem processes and society’s use of natural resources that biodiversity change is now considered an important global change in its own right (Sala, et. al 2000). At present, species are going extinct at a rate 100 times the natural background rates (Pimm and Lawton, 1998). Beginning of the human civilization is believed to on the banks of world’s major rivers. Due to this, river basins are renowned as the cradles of civilization and cultural heritage. Ancient and modern communities alike have depended on rivers for livelihood, commerce, habitat and the sustaining ecological functions they provide. Throughout the history alterations to rivers – have affected riverine communities in one-way or other (WCED 2000). Human pressures have now reached a state where the continental aquatic systems can no longer be considered as being controlled by only Earth system processes, thus defining a new era, the Anthropocene (Maybeck 2003). 2 Riverine ecosystems are critical components of the global environment. In addition to being essential contributors to biodiversity and ecological productivity, they also provide a variety of services for human beings, including water for drinking and irrigation, recreational opportunities, and habitat for economically important fishes. However, aquatic systems have been increasingly threatened, directly and/or indirectly, by human induced activities. Aquatic ecosystems, in addition to the challenges posed by land-use change, environmental pollution, and water diversion, are expected to experience the added stress of global climate change. Available information suggests that over the past 30 years, freshwater biodiversity has declined much faster than either terrestrial or marine biodiversity. The ever-increasing demands placed on freshwater resources in most parts of the world has led to the uneven and continued loss of biodiversity. Pollution, siltation, canalization, water abstraction, dam construction, over-fishing, and introduced species will all play a part, although their individual impacts will vary regionally. The greatest effects will be on biodiversity in fresh waters in highly diverse and densely populated parts of the tropics, particularly South and Southeast Asia, and in dry-land areas, although large-scale hydro-engineering projects proposed elsewhere could also had catastrophic impacts (Jenkins 2003). River ecosystems of India The Indian sub-continent is traversed by a large number of rivers, which played a major role in shaping the history of human civilization in the sub-continent. It has very rightly been said that River Ganga has been the cradle of civilization in the Indian sub-continent. The rivers have been extensively used for various purposes, including irrigation, drinking water, recreation, fishing, transport, etc (Venkataraman, 2003). There is a dense network of rivers all over India, constituting the most important water resources for the country. The river systems are grouped on the basis of their drainage - basin area into major (more than 20,000 km2), medium (2000 – 20,000 km2) and minor (<200 km2) rivers. Accordingly, 15 major, 45 medium and 120 minor systems, besides numerous ephemeral streams in the western arid region drain the mainland. The rivers of the Indian mainland can be grouped according to their origin, into Himalayan and peninsular rivers (Sinha and Sinha 2003). Human population in India has reached 102.8 crores in 2001, which was 84.6 crores in 1991 with 21.3% increase (Census of India, 2001). Major portion of the water requirement of this population is met from the rivers. Consequently, human impacts on rivers throughout the country extend well beyond direct use of water to all activities in the floodplain and the entire catchment. Uncontrolled discharge of untreated (or partly treated) muncipal sewage and industrial effluents has reduced many river stretches into wastewater drains (Gopal, 2000). Now India is determined to go ahead with its single- point agenda of economic growth, the proposal to link major rivers for combating local water deficits. Over the next 10 years, it is envisaged that 37 major rivers in India will be linked through 12,500 km of canals and requiring the construction of at least 400 reservoirs (Daniels, 2004). Western Ghats’ scenario Western Ghats that lies in the western part of peninsular India is a series of hills stretching over a distance of 1,600 km from north to south and covering an area of about 3 1,60,000 Sq. km. Western Ghats’ extraordinary biological heritage makes the region one of the highest priorities for international conservation efforts and is recognized as one of the 25-biodiversity hotspots of the world (Myers et al., 2000). These Ghats are known for exceptional species richness and endemism