Combined effects of zinc and algal food on the competition between planktonic rotifers, Anuraeopsis fissa and Brachionus rubens (Rotifera)
Por:
Sarma S.S.S., Azuara-García R., Nandini S.
Publicada:
1 ene 2007
Resumen:
We evaluated the combined effects of algal (Chlorella vulgaris) food levels (low, 0.5 × 106 (or 2.9 ?g C ml-1); and high, 1 × 106 cells ml-1 (or 5.8 ?g C ml-1)) and zinc concentrations (0, 0.125, and 0.250 mg l-1 of ZnCl 2) on the competition between two common planktonic rotifers Anuraeopsis fissa and Brachionus rubens using their population growth. Median lethal concentration data (LC50) (mean ± 95% confidence intervals) showed that B. rubens was more resistant to zinc (0.554 ± 0.08 mg l-1) than A. fissa (0.315 ± 0.07 mg l-1). A. fissa when grown alone or with Zn was always numerically more abundant than B. rubens. When grown in the absence of zinc, under low- and high-food levels, the peak abundances of A. fissa varied from 251 ± 24 to 661 ± 77 ind. ml-1, respectively, and the corresponding maxima for B. rubens were 52 ± 3 and 102 ± 18 ind. ml-1. At a given food level, competition for food reduced the peak abundances of both rotifers considerably. Increase in Zn concentration also lowered the rotifer abundances. The impact of zinc on competition between the two-rotifer species was evident at low-food level, mainly for A. fissa. At zinc concentrations of 0 and 0.125 mg l -1, the populations of both rotifers continued to grow for about 10 days, but thereafter B. rubens began to decline. Role of zinc on the competitive outcome of the two species is discussed in relation to the changing algal densities in natural water bodies. © 2007 Springer Science+Business Media B.V.
Filiaciones:
Sarma S.S.S.:
Division of Research and Postgraduate Studies, National Autonomous University of Mexico, Campus Iztacala, Av. de Los Barrios no.1, Los Reyes, Tlalnepantla, State of Mexico CP 54090, Mexico
Azuara-García R.:
Postgraduate Program in Marine and Freshwater Sciences, National Autonomous University of Mexico, Mexico City, Mexico
Nandini S.:
UIICSE, National Autonomous University of Mexico, Campus Iztacala, Av. de los Barrios no. 1, Los Reyes, Tlalnepantla, State of Mexico CP 54090, Mexico
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