Phytoplankton Pigments: In vivo bio-optical properties of phytoplankton pigments

Introduction In this chapter we focus on spectral in vivo bio-optical (absorption, scattering and fluorescence) characteristics of phytoplankton. As such, the importance of measuring in vivo bio-optical properties of a culture, population or mixed community of phytoplankton is that the optical signatures provide us with important taxonomic, phylogenic and eco-physiological information. The optical signature in the PAR region (400–700 nm) of phytoplankton is central to understand the processes affecting the optical properties of the water column, the potential rate of primary production, phytoplankton community structure, and phytoplankton physiology and photo-ecology. This chapter gives important bio-optical information for interpretation of data from remote sensing and in situ monitoring of phytoplankton blooms (Chapter 14, this volume) and as an aid to study photo-acclimation processes (Chapter 11). Light, or more precisely, a flux of photons (quanta) hitting a living phytoplankton cell can either be absorbed, scattered, transmitted, emitted as fluorescence/heat or induce photochemistry. The absorption spectrum (PAR) of phytoplankton is a composite signature of cellular photosynthetic and photoprotective pigments, with some contribution from intermediary electron transport components (e.g. flavins, quinines and cytochromes). The nature of the pigmentation varies significantly among phytoplankton groups and with environmental conditions.