Seasonal pattern and induction cues of diel vertical migration of Chaoborus flavicans in Lake Fukami‐ike, Nagano, Japan

Abstract

AbstractDiel vertical migration (DVM), which is a well‐known behavior of planktonic organisms, is influenced by several factors, including predation, ultraviolet radiation, temperature, and food. The larvae of Chaoborus (Diptera) exhibit DVM in lakes and ponds. However, it is unclear whether the DVM of Chaoborus larvae changes seasonally and whether induction cues influence the seasonal pattern of DVM. In this study, we report that Chaoborus larvae showed DVM throughout the year in a eutrophic lake (Lake Fukami‐ike, Japan). Our laboratory experiment demonstrated that the larvae showed DVM in response to light change even when they were not exposed to fish kairomone at water temperatures typical of winter and summer in the studied lake. These results differed from those of previous studies on other Chaoborus populations showing that both fish kairomone and light change were necessary to induce DVM, which suggests variation in the induction cues among local populations. We suggest that for Chaoborus larvae in Lake Fukami‐ike, a seasonally continuous DVM induced solely by light change is adaptive to their particular habitat where the population is exposed to fish predation throughout the year.