Biodiversity and Abundance of Rotifers in Bueng Boraphet, Nakhon Sawan Province, Thailand(Thai)

Abstract

The species diversity and abundance of rotifers in Bueng Boraphet, Nakhon Sawan Province, Thailand, were studied for two years between August 2002 and April 2004. Seventeen families, twenty-nine genera and 103 species were identified, and Brachionus nilsoni (Ahlstrom) is new to Thailand. The most diverse family was Lecanidae with 34 species, followed by Brachionidae with 19 species. The number of species recorded in this study was between 66 and 90. The number of species recorded in the rainy, cool and hot seasons were not different significantly (p>0.05) and most of the taxa recorded are circumtropical species. In the first year (August 2002-April 2003), the species richness in the rainy season was 74 species (71.8 %), followed by hot and cool seasons with 70 (67.9 %) and 66 species (64.1 % of the total species recorded), respectively. The average maximum and minimum abundances of 1,096+339 and 327+157 individuals/litre were recorded in cool and hot seasons, respectively. The most abundant species were Polyarthra vulgaris (Carlin) and Anuraeopsis coelata (De Beauchamp). In the second year (August 2003-April 2004), the species richness in the rainy season was 90 species (87.4 %), followed by hot and cool seasons with 80 (77.7 %) and 78 species (75.7 % of the total species recorded), respectively. The average maximum and minimum abundances of 621+307 and 445+288 individuals/litre were recorded in hot and rainy seasons, respectively. The most abundant species were P. vulgaris and Keratella tropica (Apstein). However, 76 species (73.8 %) were found in all seasons. Common and perennial species were P. vulgaris and Lecane bulla (Gosse). In addition, the species richnesses correlated with the abundance. There was low species diversity, e.g. 66 species in cool season 2002, due to high abundance of dominant species (P. vulgaris and Keratella cochlearis (Gosse) with 1,426 and 852 individuals/litre, respectively). This study suggests that Bueng Boraphet was disturbed by human activities.