Rapid Bioassessment of Magura haor (Floodplain wetland), Cachar District, Assam, India using Aquatic Insects

Investigation on the water quality of the floodplain wetland, Magura through rapid assessment survey using aquatic insects for the four seasons were done during 2013-14. Aquatic insects were collected from the two sites and were identified up to family level. All together 5 orders (Hemiptera, Coleoptera, Odonata, Ephemeroptera and Diptera) and 21 families were recorded from the wetland. 17 families from site 1 (Hemiptera- 7 families, Coleoptera- 4 families, Odonata- 3 families, Ephemeroptera- 1 family and Diptera- 2 families) and 18 families from site 2 (Hemiptera- 6 families, Coleoptera- 6 families, Odonata- 2 families, Ephemeroptera- 1 family and Diptera- 3 families) were recorded. Four family level biotic indices- SIGNAL 2, ASPT, BMWP and FBI were used to determine the status of the water quality. According to SIGNAL 2 and BMWP scores it was moderately polluted, whereas ASPT showed doubtful quality but FBI proved very good (site 1) and good water condition (site 2). This study revealed that only one biotic index cannot give proper justification of the water quality status of a wetland.