Planktology is the science and teaching about organisms that float in the ocean and freshwater, which are labeled plankton. It is a section of oceanography. it is also covering topics like primary production, predator prey relationships and energy flow. Especially the flow of carbon is a hot issue in the last years. Plankton drives the "biological pump", a process by which carbon is transported to the abyss by the help of the physiology of the organisms. Such processes are important in the discussions about carbon sequestration, a big hope to catch some of the carbon which is currently accumulating in the atmosphere due to combustion of fossil fuel (anthropogenic global warming). Modern planktology also includes now more and more the behavioral aspects of the life adrift, engaging modern in situ imaging devices, like in the LEO project, some even allowing the public to participate online.
The alternative form planctology is a mis-spelling.