Do the rivers of Chota Nagpur Dry Forests (Jharkhand), Damodar and Subarnarekha differ in biodiversity of aquatic macrozoobenthos, functional feeding groups and biological water quality?

Abstract

The Damodar and Subarnarekha Rivers are the first and second largest running waters of Jharkhand, having variable river bed morphology with naturally hard substrates. The riverine biodiversity is outstanding, as it includes endemic taxa on species and subspecies levels. Aquatic habitats are mostly colonized by native species. Macrozoobenthic animals are important bioindicators of the habitat quality of the river and are used for rapid assessment of river quality globally. In order to have preliminary information on the biodiversity of macrobenthos, the first survey was undertaken to find the impact of domestic pollution, mining, and thermal power plants on the aquatic life of the Damodar in May 2004. On the basis of our observations and species records, systematic field sampling for macro-benthic invertebrates in the Damodar and Subarnarekha Rivers was conducted from 2007 to 2012 during different hydrological conditions to cover the seasonal variation. Synoptic sampling was done to allow comparison between the two rivers. Aquatic invertebrate fauna has been inventoried with 124 identified taxa. The highest proportion of functional feeding groups recorded were detritivores, followed by carnivores and herbivores, respectively. This present study demonstrates the seasonal disappearance of macrozoobenthic invertebrates caused by urban and industrial pollution and that the fauna of the two main rivers of Jharkhand are similar in species inventory. This reflects the ecological conditions of the shared ecoregion known as Chota Nagpur Dry Forests. The results of the present research provide an essential database to evaluate the future environmental impact of restoration and changes in water quality.