Effect of salinity on competition between the rotifers Brachionus rotundiformis Tschugunoff and Hexarthra jenkinae (De Beauchamp) (Rotifera)
Por:
Sarma S.S.S., Elguea-Sánchez B., Nandini S.
Publicada:
1 ene 2002
Resumen:
We studied the effect of different concentrations (0, 3, 6, 9 and 12 g l-1) of sodium chloride at one food level of Chlorella (1 × 106 cells ml-1) on competition between the rotifers B. rotundiformis and H. jenkinae, both of which were isolated from a saline lake. The population growth experiments were conducted for 3 weeks. Both the rotifer species did not survive beyond one week at a salinity of 0 g l-1. Regardless of salt concentration and the presence of a competitor, H. jenkinae reached higher densities than B. rotundiformis. When grown alone, both B. rotundiformis and H. jenkinae showed optimal peak population densities at the salinity of 6 and 9 g l-1. Since biomass wise, B. rotundiformis was larger than H. jenkinae, it showed a lower numerical abundance. Thus, the maximum peak population densities of B. rotundiformis and H. jenkinae recorded in this study were 107±3 and 203±28 ind. ml-1. The maximal rates of population increase for B. rotundiformis and H, jenkinae when grown alone were 0.264±0.003 and 0.274±0.004, respectively. Our results also indicated that B. rotundiformis and H. jenkinae coexisted better at a salinity of 6 and 9 g l-1 of sodium chloride while a salinity of 3 g l-1 favoured Hexarthra over B. rotundiformis. At 12 g l-1, both the rotifer species grown alone or together showed lower growth rates compared to those at lower salinity levels. Except 0 g l-1, in all other salinity treatments, H. jenkinae was a superior competitor to B. rotundiformis.
Filiaciones:
Sarma S.S.S.:
Division of Research and Postgraduate Studies, Campus Iztacala, National Autonomous University of Mexico, Av. de los Barrios s/n Los Reyes, Tlalnepantla, St. of Mexico CP 54090, Mexico
Elguea-Sánchez B.:
Colegio de Ciencias y Humanidades, Plantel No. 2, Naucalpan, Mexico
Calzada de los Remedios S/N, Col. Bosque de los Remedios, Municipio de Naucalpan de Juárez, Estado de Mexico C.P. 53030, Mexico
Nandini S.:
Division of Research and Postgraduate Studies, Campus Iztacala, National Autonomous University of Mexico, Av. de los Barrios s/n Los Reyes, Tlalnepantla, St. of Mexico CP 54090, Mexico
|