Use of Imaging Particle Analyzer (FlowCam®) for characterizing metrics for zooplankton

Evaluations of zooplankton body size, biomass, density, and community composition are critical for understanding ecosystem structure and function. The process of enumerating, identifying, and measuring zooplankton has traditionally been accomplished through microscopy, which can be time intensive and accrue high-cost over time. The development of fully or semi-automated methods are becoming viable and potentially cost effective alternatives to historic approaches. Here we present an approach to studying zooplankton using the imaging particle analyzer FlowCam and FlowCam Macro, along with portions of a study conducted by the Illinois Natural History Survey that compared FlowCam and microscopy for characterizing mesozooplankton body size, biomass, density, and community structure. In the study, estimates of body size varied slightly, but variation was consistent due to varying methods in which size was estimated. A strong relationship was observed in density and community structure estimates between FlowCam and microscopy methods and underestimation from the FlowCam® can be rectified with mathematical equations. Similarly, individual biomass estimation from 2-dimentional profile area derived from FlowCam was similar to estimates from a commonly used length-mass regression model. Under most conditions evaluated, the semi-automated approach yielded an average time savings of 11 minutes per sample compared to the traditional microscopy method.