EFFECTS OF AGROCHEMICAL RESIDUES ON AQUATIC INVERTEBRATES IN SEMI-ORGANIC RICE FIELDS
Keywords:Ecotoxicology, Semi-Organic Rice Farming, Aquatic Invertebrate, Soil Ecology
This study presents a case study for rice farming change from a conventional to semi-organic process. Alterations of aquatic invertebrate composition and diversity between these two rice farming methods were compared. Aquatic invertebrates were collected in flooded rice fields between August and October 2015. Four phyla comprising 12 taxa were identified with average abundances in conventional and semi-organic samples of 5,717 and 10,676 individuals/m2, respectively, while the Shannon diversity index ranged between 0.45-0.62 and 0.35-0.59, respectively. Evenness index in conventional and semi-organic ranged between 0.26-0.65 and 0.23-0.71 respectively, while the dominant index was highest in semi-organic farming. Water quality parameters as temperature, dissolved oxygen and pH were not significantly different between the two farming methods. Contamination occurred from chemical substances remaining in semi-organic rice fields. Abundant pollution indicator species such as Oligochaeta, ChironomidaeandViviparidae suggested pesticide or herbicide contamination from water sources as agrochemical residues persisted from previous conventional rice farming.