On the accuracy of assessing copepod size and biovolume using FlowCAM and traditional microscopy

Abstract

In this paper, based on the biovolume estimation of different genera of copepods, we present the fact that only the Area-based Diameter (ABD) algorithm of FlowCAM has the efficiency to measure the bio-volume of copepods better than traditional microscopy. Also, we have demonstrated that the efficiency of the Equivalent Spherical Diameter (ESD) algorithm of FlowCAM over traditional microscopy is lesser while assessing the copepod biomass, and it depends on the morphological characteristics of various copepod genera. The ESD algorithm overestimates (8-140 times) while traditional microscopy method underestimates (2-8 times) the copepod biovolume, chiefly because of the inclusion of the entire image field for volume estimation in the former case and avoidance of extended body parts such as appendages in the latter case. These observations have special implications in aquatic environmental monitoring as many of the modern researchers prefer FlowCAM as a better tool to accurately quantify plankton biomass.