Estimating primary productivity of marine macroalgae in East Antarctica using in situ fluorometry

Abstract

Photosynthetic activity of marine macroalgae in the Windmill Islands, East Antarctica, was measured in situ using submersible modulated fluorometers. An empirical relation incorporating terms for respiration and non-linear electron transport was derived from simultaneous in vivo measurements of effective quantum yield () and oxygen evolution. This relation was used with in situ measurements of and photosynthetic photon flux density acquired over 24-h periods to estimate oxygen evolution rates of algae over the course of the measurement period. Productivity ranged from −8 to 19 µmol O2 g−1 FW h−1 (FW = fresh weight), with daily carbon gain ranging from −1.5 to 3.6 mg C g−1 FW d−1 for midnight ice-covered algae and midday ice-free algae, respectively. These values were similar to published values of productivity of Antarctic species derived from oxygen- and carbon-based techniques. The technique described here provides a simple and rapid means of estimating primary productivity in marine systems.