Estimation of calanoid copepod prosome length from pixel-based measurements derived from the ZooScan and ZooProcess systems

Abstract

Computer-automated image capture and analysis techniques are increasingly used for the study of plankton. Unfortunately, because most of the automatic image processing software packages recognize only numbers of pixels and grey scale values, although a great many parameters are automatically measured on each image (area, perimeter, average level of grey, etc. . . .), these do not directly equate to variables that appear in the biological literature. The relationships between prosome lengths and computer-generated characters were derived from images acquired using the ZooScan system for two of the most common copepod families off south–eastern Japan: Calanoida and Poecilostomatoida. The equivalent spherical diameter (ESD), a character automatically measured by the ZooScan-ZooProcess system, was found to be highly correlated with prosome length in the two orders, and a single equation could be established (regression coefficient r² = 0.943) for all Calanoida excepting those of the family Eucalanidae: PL (mm)＝0.08＋0.023*ESD (pixels).