ABSTRACT
Ciliates may be a major component of planktonic food webs. These protists act as heterotrophs, functional autotrophs, and mixotrophs and may use resources more rapidly and efficiently than metazoan competitors. Consequently, planktonic ciliates influence energy flux both as primary and secondary producers and by contributing to nutrient regeneration. Typically in food web studies, ciliates have been lumped into a few groups identified by silhouettes (all that can be seen in settling chambers). Protargol is a recommended approach to examine ciliates. Originally a brand name, protargol is now vernacular for the silver proteinate stain. Many ecologists view protargol silver staining of ciliates with trepidation, maintaining that it is difficult and time consuming. Slightly modified quantitative protargol stain (QPS), descriptions of the reactions likely to occur during staining, and adjustments that can overcome the variability with which taxa react to staining.
