Planktos

Planktos is a term of Greek origin meaning wandering or drifting. In biology, the root planktos appears in the word plankton, the collective term for small drifting organisms in aquatic environments. Plankton includes phytoplankton (photosynthetic) and zooplankton (heterotrophic). The distinction between plankton and nekton is based on locomotion.

In addition to its scientific use, Planktos, Inc. was a company formed in the early 2000s in California that proposed ocean iron fertilization as a geoengineering method to enhance phytoplankton growth and sequester atmospheric CO2. The company planned field trials in the open ocean, notably a proposed expedition using a research vessel to release iron near the Galápagos region. The plan attracted significant criticism from scientists, environmental groups, and regulators who argued about uncertainties and potential ecological risks, including disruption of marine ecosystems and possible carbon cycle effects.

Due to regulatory, financial, and reputational challenges, the company suspended its activities and eventually ceased operations within a few years. Its case is frequently cited in discussions of geoengineering research governance and the ethics of large-scale ocean fertilization.