The comprehensive effects of varied photoperiods and algal abundance fluctuations on the key life history parameters of herbivorous rotifer Brachionus plicatilis

The variation of photoperiod affects the photosynthesis of primary producer algae in the ocean, leading to fluctuations in algal abundance. The changes in photoperiod and algal abundance may have complex integrated effects on primary consumer herbivorous zooplankton. Therefore, in this study, we exposed two clones of rotifer Brachionus plicatilis to the combinations of five photoperiods (0 L: 24 D, 6 L: 18 D, 14 L: 10 D, 18 L: 6 D, and 24 L: 0 D) and three algal abundances (3 × 10⁴, 10 × 10⁴, and 100 × 10⁴ cells mL⁻¹) and recorded the key life history traits. Results showed that the two clones of rotifer B. plicatilis had similar responses to the combinations of photoperiod and algal abundance. Reduced algal abundance delayed development and impaired fecundity, but prolonged survival time. Algal abundance fluctuations affected the resource allocation patterns of rotifers. Short photoperiods had a tendency to reduce the life span of rotifers. There was a significant interaction between photoperiod and algal abundance on the key life history parameters of rotifers. As algal abundance decreased, extreme photoperiods delayed the sexual maturity time of rotifers. Low algal abundance exacerbated the negative effects of light deficiency on rotifers, while high algal abundance alleviated the effects of the extreme photoperiod. Such findings are of great significance for understanding the effects of food fluctuations on the structural stability of the bottom food chain in aquatic ecosystems under the variation of photoperiod with different latitudes and seasons.