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 degrees and 25 degrees C) and food densities (1 x 104 and 1 x 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 degrees C fed with N. oculata (1 x 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 degrees 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 degrees C. Moreover, the rotifer fed with S. obliquus reached the maximum size. Our hypothesis is that when temperature increase 5 degrees C, the rotifer may shorten its embryonic development, thereby increasing r and net reproduction rate.

Automated summary

This study evaluated the combined effects of different temperatures and food densities on the life history of Euchlanis dilatata, and investigated the impact of temperature on various biological processes. The results showed that the highest instantaneous growth rate was achieved when E. dilatata was fed with N. oculata at 25 degrees C, while the lowest growth rate was observed when fed with C. vulgaris at both temperatures. Additionally, at 20 degrees C, the mean generation time and age at first reproduction exhibited higher activation energy.