In environments with strong seasonality, many herbivorous zooplankton remain active only during the productive season and undergo a period of inactivity and suppressed development termed ‘diapause’ during the unproductive season. The ability to time the diapause entry and exit in response to the seasonality of the environment is thus essential for their survival. However, timing of diapause may become challenging when environmental conditions vary stochastically across shorter and longer timescales, and particularly when zooplankton lack external cues to predict these variations. In this study, we used a novel individual-based model to study the emerging patterns of diapause timing of the high-latitude marine herbivorous copepod Calanus finmarchicus under shorter- (6-h) and longer-term (interannual) environmental stochasticity. The model simulated growth, development, survival and reproduction (income breeding) of a C. finmarchicus population over multiple calendar years and traced the emergence of behavioral responses and life history strategies. The emergent timing of diapause entry and exit were robust to shorter-term environmental stochasticity, which was manifested through morphological (i.e., body and energy reserve sizes) and behavioral plasticity (i.e., diel vertical migration). Longer-term stochastic variations of temperature and food environments altered the timing of diapause entry, which occurred earlier in warmer years with higher growth potential and vice versa. Irrespective of the modelled environmental variability, diapause exit occurred asynchronously throughout the year. This appeared to be a consequence of a diversified bet hedging strategy, where parents spread the starvation mortality risk of ascending to the upper pelagial at food-deprived times of the year among their offspring. This was a potent strategy, particularly in simulations where the timing of the algal bloom varied stochastically between years, since a fraction of the population was present in the upper pelagial year-round and those that coincided with the emergence of the pelagic primary production survived and produced the next generation.

在季节性强的环境中，许多食草浮游动物只在生产季节保持活跃，在不生产季节经历一段不活动和抑制发育的时期，称为“滞育”。因此，根据环境的季节性来确定滞育进入和退出时间的能力对于它们的生存至关重要。然而，当环境条件在较短和较长的时间尺度上随机变化时，尤其是当浮游动物缺乏外部线索来预测这些变化时，滞育的时间可能会变得具有挑战性。在这项研究中，我们使用一种新的基于个体的模型来研究高纬度海洋食草桡足类Calanus finmarchicus滞育时间的新模式在短期（6 小时）和长期（年际）环境随机性下。该模型模拟了C. finmarchicus 的生长、发育、生存和繁殖（收入繁殖）多个日历年的人口，并追踪行为反应和生活史策略的出现。滞育进入和退出的出现时间对短期环境随机性是稳健的，这通过形态学（即身体和能量储备大小）和行为可塑性（即日间垂直迁移）表现出来。温度和食物环境的长期随机变化改变了滞育进入的时间，滞育进入发生在较温暖的年份更早，具有更高的生长潜力，反之亦然。无论模拟的环境变化如何，滞育退出全年都是异步发生的。这似乎是多元化投注对冲策略的结果，父母在一年中食物匮乏的时期将上升到上层层的饥饿死亡风险分散到他们的后代中。这是一种有效的策略，特别是在藻华时间随年份随机变化的模拟中，因为一小部分种群全年都存在于上层浮游层中，而那些与浮游初级生产出现一致的种群幸存下来并且产生了下一代。