Diel vertical migration (DVM) is the most common behavioral phenomenon in zooplankton, and numerous studies have evaluated DVM under strong seasonality at higher latitudes. Yet, our understanding of the environmental drivers of DVM at low latitudes, where seasonal variation is less pronounced, remains limited. Therefore, we here examined patterns of vertical distribution in copepods in six subtropical Bahamian blue holes with different food web structure and tested the role of several key environmental variables potentially affecting this behavior. Day and night samplings showed that copepods generally performed DVM, characterized by downward migration to deeper depths during the day and upward migration to surface waters at night. Across all blue holes, the daytime vertical depth distribution of calanoid copepods correlated positively with both predation risk and depth of food resources (Chlorophyll a), but was less affected by ultraviolet radiation (UVR). A potential explanation is that since UVR is a continuous threat across seasons, zooplankton have established photoprotective pigmentation making them less vulnerable to this threat. The copepods also showed a size-structured depth segregation, where larger individuals were found at deeper depths during the day, which further strengthens the suggestion that predation is a major driver of DVM in these systems. Hence, in contrast to studies performed at higher latitudes, we show that despite the constant exposure to UVR, predator avoidance and food availability are the most pronounced drivers of copepod DVM at those low latitudes, suggesting that the main driver of DVM may vary among systems, but also systematically by latitude.

Diel垂直迁移（DVM）是浮游动物中最常见的行为现象，许多研究已经评估了DVM在较高纬度的强季节性下的情况。但是，我们对低纬度地区DVM的环境驱动因素的了解仍然有限，那里的季节变化不太明显。因此，我们在这里研究了六个具有不同食物网结构的亚热带巴哈马蓝洞中co足类的垂直分布模式，并测试了可能影响这一行为的几个关键环境变量的作用。白天和晚上的采样表明，co足类动物通常执行DVM，其特征是白天向下迁移到更深的深度，晚上向上迁移到地表水。在所有的蓝色洞中a），但受紫外线（UVR）的影响较小。一个可能的解释是，由于紫外线辐射在各个季节都是一个持续的威胁，浮游动物已经建立了光保护性色素沉着，使它们对这种威胁的抵抗力降低。pe足类动物还表现出大小结构的深度隔离，在白天，较大的个体被发现在更深的深度，这进一步证实了捕食是这些系统中DVM的主要驱动力。因此，与在较高纬度上进行的研究相反，我们表明，尽管持续暴露于UVR，但在那些低纬度下，捕食者的回避和食物供应是co足类DVM的最明显驱动力，这表明DVM的主要驱动力可能会因系统而异，也可以通过纬度系统地进行。