Seasonal Variation of Macrofuana in Harohar River, Bihar

Harohar river sub-basin is situated between Lat 24o10’N and 25o30’N and long 84o40’E and 86o8’E. The basin is distinctly divided in two zones. The upper zone in the south, lying in Chhotanagpur is hilly and covered with forest where as the lower zone falls in the gangetic planes. The basin is mainly drained by the river Harohar and Sakri. The lower portion of the basin is saucer shaped and forms a group of Tals commonly known as Mokama Group of Tals. Present investigation was carried out to assess the seasonal variation of benthic macro-invertebrates from the Harohar river, Lakhisarai, Bihar during December, 2003 to November, 2005. The seasonal benthic diversity was correlated with various physic-chemical parameters which documented that the macrobenthic diversity is mostly regulated by the dissolved oxygen in the water while temperature and free CO2 were found to be inversely correlated with the benthic fauna. Maximum diversity of benthos was reported at the upstream site (‘H’ 0.204) during the winter season while it was recorded minimum during the rainy season at all the sites. Maximum diversity is reported during the winter season at all the sites. The benthic fauna is represented by three phylum, 4 classes and 10 orders with Insecta emerging as the most dominant class. Maximum genera were reported from midstream site as it acts as ecotone between upstream and downstream.