Zooplankton are important in ocean ecosystems as they link primary productivity to higher trophic levels. Large planktivores such as reef manta rays (Mobula alfredi) often aggregate at predictable locations and rely on zooplankton productivity hotspots to meet their energetic requirements. However, limited high-resolution data of zooplankton concentrations at these predator foraging grounds remains a major obstacle to understanding their feeding environments.
Certain acoustic Doppler current profilers (ADCP) have the capacity to undertake sustained (3 months) high vertical resolution (3mm) biological surveys using the integrated wideband echosounder. In this study, predator-prey interactions were investigated using data collected by bed-mounted, upwards-facing Nortek Signature ADCP deployed in Hanifaru Bay, the Maldives. The acoustic data were supported by in situ zooplankton samples and video surveys of M. alfredi behaviour to provide a representative baseline to validate the acoustic backscatter measurements from the ADCP. These localised datasets that link the hydrodynamics responsible for plankton accumulation to the foraging landscape of M. alfredi will help to understand the mechanisms that link predator-prey interactions to the properties of their habitat. The novel use of this technology expands the application of ADCP data for taxa that are complex and difficult to observe.