Abstract
Recently, new experimental techniques to map two-dimensional oxygen distributions in benthic communities have been developed. The oxygen distributions are visualized by the use of planar sensor foils with an oxygen-sensitive fluorophore layer, containing a photo-stable ruthenium complex that is reversibly quenched by oxygen. Recording the fluorescence intensity from the sensor foil using a light-sensitive digital camera system allows the two-dimensional oxygen distribution to be quantified over an area of several square centimeters at a spatial resolution better than 50 mum. Larger areas can be covered by changing the optics of the system; however, the spatial resolution decreases. Since the first primitive approaches, more sophisticated systems have been developed, in which both fluorescence intensity and fluorescence lifetime imaging is possible in one as well as two dimensions (planar optodes). We have applied planar optodes for mapping the oxygen dynamics in benthic systems exhibiting various degrees of heterogeneity (e.g., biofilms, microbial mats, and sediments with and without significant faunal activity). The technical developments of sensors, camera systems, and applications of the imaging techniques are reviewed here.