Population dynamics and diversity of Odonata (insecta) at Mini and Mahi rivers of Gujarat, India

Abstract

Population dynamics, diversity and community structure of Odonata were studied on three adjacent riparian microecosystems in Vadodara district, Gujarat, India. Population dynamics was studied by observing their population by point count method on three microhabitats (Mini River at Sankarda, Sindhrot and Mahi River at Fazalpur). In the course of a twenty-eight-week study, a total of 4783 Odonata were encountered on three microecosystems. Odonata density 9% throughout September 2014 (39th Meteorological Week) and gained its peak during October 2014 (44th Meteorological Week). A definite drop in the density was observed during November 2014 (48th Meteorological Week) and it achieved precisely 1% throughout December 2014 (51st Meteorological Week). Amongst the three microecosystems, at Fazalpur, species richness began rising from the 4th week of September (6%) and made it to its highest (11%) throughout the 4th week of October. At Sankarda, maximum absolute richness (12.61%) was recorded in 3rd week of October. At Sindhrot, the relative abundance of odonates started increasing in 3rd week of September (7%) and achieved its highest (13%) during 4th week of October. A total of twenty-five species were encountered in the terrain. The diversity index was maximum for Sankarda (2.35) followed by Fazalpur (2.27) and Sindhrot (2.01). A total of four species (Ditch Jewel (26.6%), Pigmy Dartlet (19.5%), Green Marsh Hawk (10.3%) and Senegal Golden Dartlet (8.3%) were dominant in all three microhabitats.