Assessment of adaptive strategies on life history of the rotifer Euchlanis dilatata (ROTIFERA) at different temperature and food regime

The combined effects of two temperatures (20˚ and 25˚C) and food densities (1×10⁴ and 1×10⁶ cells/mL) of three microalgae, <i>Chlorella vulgaris</i>, <i>Nannochloropsis oculata</i> and <i>Scenedesmus obliquus</i> on the life history of <i>Euchlanis dilatata</i> were evaluated. Our work integrated: effects of temperature on the activation energy (<i>Ea</i>), and evaluation of the rate of decrease or increase through the temperature coefficient (<i>Q</i>10) in the different biological processes of the<i> </i>life table of<i> E. dilatata</i>, including, morphometric values and hatching egg percentages. The best conditions to reach the highest instantaneous growth rate (<i>r</i>) in <i>E. dilatata</i> were 25˚C fed with <i>N. oculata</i> (1×10⁶ cells/mL) while the lowest <i>r</i> value was registered with <i>C. vulgaris</i> with both temperatures. In the mean generation time and age at first reproduction, the Ea was higher at 20˚C, where <i>Q</i>10 values < 1 indicate that these rates decrease with increasing the temperature. We found an exception to the temperature-size rule when rotifer was fed <i>C. vulgaris </i>at 25˚C. Moreover, the rotifer fed with <i>S. obliquus</i> reached the maximum size. Our hypothesis is that when temperature increase 5°C, the rotifer may shorten its embryonic development, thereby increasing <i>r</i> and net reproduction rate.