600 / 2024-09-18 15:58:57

Effects of Temperature Variation on Copepod Grazing, Respiration, Growth, and Reproduction: A Multigenerational Experiment

temperature change,copepod feeding,copepod respiration,copepod reproduction

Temperature changes have been shown to influence the physiological activities, growth, and reproduction of marine zooplankton, particularly copepods. However, research on different life stages, especially egg-carrying females, is limited, and few studies have conducted multi-generational continuous experiments. In this study, we examined the effects of temperature changes (either a decrease or an increase of 7°C from 25°C) on the grazing rate, respiration rate, growth, and reproduction of the euryhaline calanoid copepod Pseudodiaptomus annandalei collected from Wuyuan Bay, Xiamen, China. The grazing and respiration rates of egg-carrying females responded differently to acute temperature changes compared to juveniles (nauplii and copepodite), males, and non-egg-carrying females. An increase in temperature significantly enhanced their grazing rate by 32% (p = 0.002), while a decrease reduced it by 18% (p = 0.037). Temperature decreases significantly suppressed respiration rates by 68% (p = 0.047). Following these temperature changes, we conducted similar experiments on copepod individuals across three generations (F1, F2, and F3) at three different temperatures. Under conditions of sufficient food, the multi-generational tracking results revealed a strong impact of temperature changes on individual growth: high temperatures significantly reduced the developmental time from nauplii to adult across three generations (F1, p = 0.042; F2, p = 0.041; F3, p = 0.002), but also significantly decreased the developmental success rate (F1, p = 0.006; F2, p = 0.029; F3, p = 0.007). In contrast, low temperatures significantly extended the developmental time (F1, p = 0.002; F2, p = 0.003; F3, p < 0.001), with no significant impact on the developmental success rate. These results correlate with the grazing and respiration performance at each stage. This study underscores the impact of temperature changes on the physiological activities, growth, and reproduction of zooplankton, which is crucial for understanding the population dynamics and vulnerability of zooplankton under climate change.