The Benthic Macrofaunal Community in Agricultural Ditches in Kole Paddy Fields, Vembanad Kole Wetlands, India

Abstract

Paddy fields are connected by drainage ditches (channels),that are considered as drivers of biodiversity inagricultural areas. The macrobenthic community structure in agricultural ditches of Kole paddy fields, a part ofthe Ramsar site Vembanad kole wetlands during a complete crop season was analyzed. The macrobenthicfauna belonged to phyla Annelida, Arthropoda and Mollusca and classes Oligochaeta (60.39%), Insecta(39.31%), Mollusca (0.15%) and Hirudinae (0.15%). The class Oligochaeta was represented by Tubificidae,Naididae, Lumbriculidae; Insecta by Diptera, Coleoptera, Odonata; Mollusca by Bivalvia, Gastropoda.Composition of macrobenthos resembled to that of fresh water wetlands and paddy fields. The average numberof macrobenthos was 1475±2064 ind./m2. There was an unusually high abundance in May (5155 ind./m2); butthe environmental parameters remained usual. The abundance of good quality food or some specific, localizedcondition acting on a microscale which could not be recorded in the environmental analysis would haveresulted in the unusual distribution of the fauna. Highest diversity (3.17) and species richness (1.95) wasobserved during May 2011, during the unusual abundance. Predominant functional feeding group wascollector gatherers indicating the abundance of fine organic particulate matter (FPOM) in the substrate. Nosignificant correlation emerged between macrobenthic abundance and environmental parameters.