Measuring Photophysiology of Attached Stages of Colacium sp. by a Cuvette-Type Fast Repetition Rate Fluorometer v1

Abstract

Fast repetition rate fluorometer (FRRf) is a beneficial method for measuring photosystem II (PSII) photophysiology and primary productivity. Although FRRf can measure PSII absorption cross section (σ PSII ), maximum photochemical efficiency (F v /F m ), effective photochemical efficiency (F q ′/F m ′), and non-photochemical quenching (NPQ NSV ) for various eukaryotic algae and cyanobacteria, almost all FRRf studies to date have focused on phytoplankton. Here, we describe how to measure PSII photophysiology of an epizoic alga Colacium sp.Ehrenberg 1834 (Euglenophyta), in its attached stage (attached to zooplankton) using cuvette-type FRRf. First, we estimated the effects of substrate zooplankton (Scapholeberis mucronata O.F. Müller 1776, Cladocera, Daphniidae) on background fluorescence and σ PSII , F v /F m , F q ′/F m ′, and NPQ NSV of planktonic Colacium sp. To validate our methodology, we recorded photophysiology measurements of attached Colacium sp. on S. mucronata and compared these results with its planktonic stage. Representative results showed how the protocol can determine effects of Ca and Mn on Colacium sp. photophysiology and identify the various effects of Mn enrichment between attached and planktonic stages. Finally, we discuss the adaptability of this protocol to other periphytic algae.