Question (Bell): What types of biomass measuring techniques have been tried, which work best, and what are some of the confounding factors involved in working with these crusts? Answer: Several methods have been tried. Biomass can be quantified in direct counts using quantitative counting chambers (such as hemacytometer) and fluorescence microscopy. This gives some indication of numbers and kinds of organisms, although only the common cyanobacterial and diatom species can be identified with confidence. Obtaining biovolume estimates can be done with this method but is very laborious. Another direct method is chlorophyll a determination. This is the easiest and fastest method, but has the drawback that lichen phycobionts and free-living [...]