Diversity and Spatial Distribution of Freshwater Macro-Invertebrates in Poba Reserve Forest of Assam, India

Abstract

Seasonal investigation of aquatic macro-invertebrates in the aquatic bodies of Poba reserve forest (PRF) of Assam, India revealed altogether 55 species belonging to 29 families, 13 orders and five classes from three phyla viz., Arthropoda, Annelida and Mollusca. Class Insecta was found to be the dominant taxa represented by six orders and 17 families that comprised 35 species (63.63% of the total species richness). Gastropoda was the second dominant class represented by the families viz., Viviparidae, Ampullaridae, Pachychilidae, Thiaridae and Planorbidae, contributing with 17.24 % to the total 29 families. With two families (6.89%) class Bivalvia was represented by Unionidae and Cyrenidae families. On the contrary, the class Clitellata was comprised of only a single family and represented by the annelid Hirudinaria manillensis. Dytiscidae and Unionidae were found to be the dominant families comprised of seven species each, which contributed 12.72% to the total recorded species richness in the PRF. A spatial distribution pattern of the aquatic macro-invertebrate assemblages was observed during the study period. The highest abundance of macro-invertebrate species was recorded during the post-monsoon season (N=6148) proceeded by reduced abundance during the winter season (N=5101), pre-monsoon (N=4807) and monsoon season (N=4136) respectively. The present study is the first account of the freshwater macro-invertebrates diversity in the PRF which provides a piece of baseline information on the copiousness of different aquatic macro-invertebrate species of the reserve forest.