Section 11
Chapter 10,535

Effect of salinity on competition between the rotifers Brachionus rotundiformis Tschugunoff and Hexarthra jenkinae (De Beauchamp) (Rotifera)

Sarma, S.S.S.; Elguea-Sanchez, B.; Nandini, S.

Hydrobiologia 474: 183-188


ISSN/ISBN: 0018-8158
DOI: 10.1023/a:1016535821741
Accession: 010534076

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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 [x] 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[plus or minus]3 and 203[plus or minus]28 ind. ml-1. The maximal rates of population increase for B. rotundiformis and H, jenkinae when grown alone were 0.264[plus or minus]0.003 and 0.274[plus or minus]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.

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