THE CLADOCERA (CTENOPODA AND ANOMOPODA) IN RICE FIELDS DURING A CROP CYCLE AT NAKHON SI THAMMARAT PROVINCE, SOUTHERN THAILAND

A study of the cladoceran community in three rice fields at Nakhon Si Thammarat was carried out from June to September 2007. A total of 21 taxa of Cladocera was recorded. Of these, nine belong to the family Chydoridae, three are from the Macrothricidae, two each from the families Bosminidae, Daphniidae, Moinidae, and Sididae, and one species from the family Ilyocryptidae. The primary species of these three areas were Moinodaphnia macleayi, Diaphanosoma excision, and Bosminopsis deitersi, and these were also the most frequently found taxa. The dominant species changed throughout a crop cycle: during the seedling stage. B. deitersi (27.91%); during the growing period. Macrothrix triserialis (30.05%); and in the harvesting period, D. excisum (35.40%). Nitrogen, nitrite, and phosphate were shown to play a major role in establishing the distribution of the cladoceran community over a crop cycle.