Techniques developed for enclosing viable natural planktonic ecosystems pro vided the opportunity for prolonged and detailed investigation of dynamic events within the pelagic system of a known water body. Recent investigations into plankton ecology, using enclosure systems in dif ferent marine environments, are discussed in relation to the data obtained from the Nanaimo, British Columbia, Canada, plastic-sphere experiments of 1960 and 1962. Three types of modern enclosure experiments are recognized: floating systems within nutrient levels maintained or running down, and benthic attached...