Riffles inhabiting benthic macroinvertebrate communities in a spring• fed tributary of River Alaknanda (Garhwal Himalaya)

Bachchan Gad is a spring-fed tributary of River Alaknanda in the Garhwal region of Uttarakhand. Benthic macroinvertebrates in the riffles of Bachchan Gad was investigated during March 2008 to February 2009 at four sampling sites between 590 m tol600 m above sea level. Pre I iminary observations revealed that riffle inhabiting benthic macroinvertebrates communities in the Bachchan Gad comprised of 36 insect genera belonging to 8 orders and 29 families along with I genus each of crustacean and annelida. Dominated by Ephemeropteran, Trichopteran and Co/eopteran genera the density was highest (1300±142 Individual m?) during winter at confluence, the downstream site, it was recorded lowest (80± 15.2 Individual m) during monsoon at Pata, the headwater site.