Artificial light at night alters lake zooplankton distribution

Artificial light at night significantly impacts the vertical distribution of zooplankton in lakes, affecting both individual populations and the broader community structure. This phenomenon, known as "diel vertical migration" (DVM), is a crucial behavior where zooplankton ascend to surface waters at night to feed and descend to deeper, darker waters during the day to avoid predators. However, the presence of artificial light at night disrupts this natural cycle.

The study found that artificial light sources, such as those from human settlements, interfere with the zooplankton's ability to navigate and execute their DVM. This disruption leads to zooplankton remaining at shallower depths than they typically would, even during daylight hours. The research highlights that this change in vertical distribution occurs at both the population level, affecting the behavior of individual species, and at the community level, influencing the interactions and overall structure of zooplankton assemblages within the lake ecosystem. These alterations can have cascading effects on the food web, impacting fish populations that rely on zooplankton for food and potentially altering nutrient cycling within the lake.