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, Chlorella vulgaris, Nannochloropsis oculata and Scenedesmus obliquus on the life history of Euchlanis dilatata were evaluated. Our work integrated: effects of temperature on the activation energy (Ea), and evaluation of the rate of decrease or increase through the temperature coefficient (Q10) in the different biological processes of the life table of E. dilatata, including, morphometric values and hatching egg percentages. The best conditions to reach the highest instantaneous growth rate (r) in E. dilatata were 25˚C fed with N. oculata (1×10⁶ cells/mL) while the lowest r value was registered with C. vulgaris with both temperatures. In the mean generation time and age at first reproduction, the Ea was higher at 20˚C, where Q10 values < 1 indicate that these rates decrease with increasing the temperature. We found an exception to the temperature-size rule when rotifer was fed C. vulgaris at 25˚C. Moreover, the rotifer fed with S. obliquus reached the maximum size. Our hypothesis is that when temperature increase 5°C, the rotifer may shorten its embryonic development, thereby increasing r and net reproduction rate.