Diversity of Zooplankton in the Rice Fields in Suphan Buri Province, Thailand, with a New Record of Cyclopoid Copepod

Rice fields are dynamic ecosystems with complex niche structures for organisms, and they have been hypothesised to have high biodiversity. Accordingly, in this study, the diversity of zooplankton in rice fields in Suphan Buri Province, a large area of rice plantations in the central region of Thailand, was examined. A total of 100 species, including 52 rotifers, 18 cladocerans, and 30 copepods, were recorded, including Mesocyclops kayi, which was a new record in Thailand. A high Simpson’s diversity index (0.63) and a low Pielou’s species evenness index (0.02) confirmed various potential niches for zooplankton in this ecosystem, leading to a low Jaccard similarity index both among the current rice fields and those in other regions. Moreover, the species richness estimators suggested that more species are expected to be discovered in the rice fields. Rotifer and copepod communities are influenced by local environmental variables, including dissolved oxygen, salinity, conductivity, and chlorophyll a. The results of this study fill a gap in the knowledge regarding the diversity and ecology of zooplankton in rice fields. However, further research is needed to fully comprehend the function of this ecosystem and the actual diversity in Thailand.