ABSTRACT
In oceanic waters small heterotrophic flagellates are important components of the pelagic microbial food web and are a major link in the detrital decomposer pathway. Aggregates of phytodetritus of various sizes fall from the euphotic zone and form the main energy source for the deep sea. Aggregates generally originate in the upper mixed layer of the oceans and contain high concentrations of bacteria and bacterivorous protozoa. Protozoa from euphotic waters can function under high-pressure and low-temperature conditions to varying degrees and this seems to depend on the species. Bacterivorous flagellates can be cultured under in situ pressure and temperature from most water depths by enriching seawater with a source of particulate material in order to enhance the growth of bacterial prey. A mixed population of flagellates will develop within 4 to 8 weeks and can be maintained by adding 5 ml of the original culture to 200 ml seawater enriched with five barley grains.
