Algal composition in ecosystem of rice field under the application of herbicides and insecticides

The ecosystem of rice fields is subjected to fluctuations between dry and wet conditions. Therefore, it contains a unique biodiversity of aquatic organisms. The present study was conducted in the rice field to assess the algal composition and changes in algal population after the application of herbicides and insecticides. The physicochemical parameters were measured in situ while algal identification and examination were investigated through microscopy. The results showed that there were insignificant changes in terms of water chemistry except for the temperature. Algal examination revealed the composition of 4 phyla (Euglenophyta, Bacillariophyta, Chlorophyta and Cyanophyta) with 18 genera in the rice field. Despite the heavy application of herbicides and insecticides in the rice field, Euglenophyta significantly bloomed in the entire length of study where Euglena and Trachelomonas were the most dominant genera. Phylum of Bacillariophyta slightly bloomed during control and after the application of herbicides with the most dominant genus was Nitszchia. The application of herbicides and insecticides significantly affected the abundance of Chlorophyta even though the total abundance was below than 100 ind/mL. The Cyanophyta were the rarest algae in the ecosystem with only a single genus found, Oscillatoria. Conclusively, although the herbicides and insecticides affected the abundance of algae, but it did not induce a shift in algal community. The ecosystem of rice field supports a sustainable growth of Euglenophyta when compared to other phyla.