ASL's AZFP Documents Deep Vertical Migration Of Chaoborus Edulis In Lake Malawi

These adaptations enable this insect to escape predatory fish by descending into oxygen-depleted waters more than 200 m below the surface. Laboratory experiments demonstrated that mature larvae’s air sacs can withstand pressures equivalent to depths exceeding 500 m. A key component of the research was the deployment of ASL’s multi-frequency Acoustic Zooplankton Fish Profiler (AZFP) on a deep-water mooring in Lake Malawi. Operating continuously at depths approaching 300 m, the AZFP recorded the daily vertical migrations of Chaoborus edulis as well as detected the presence and depth of fish. Water quality parameters were also recorded, documenting dissolved oxygen, temperature, and pH throughout the water column. Together, these observations demonstrated that the larvae descend into the lake’s anoxic hypolimnion during daylight hours, effectively avoiding fish predators that remain in the oxygenated waters above. The research builds upon ASL’s 2023 AZFP Research Award, which supported the Lake Malawi field program and reflects ASL Environmental Sciences’ commitment to advancing aquatic research through innovative scientific instrumentation. Reference to paper: https://www.science.org/doi/10.1126/science.aed0667