pleuston
/ˈpljuːstɒn/ /ˈpljuːst(ə)n/Ecology
noun
Originally: the macroscopic plants found free-floating on, or partly under, the water surface. Later also: any of the organisms floating at the water surface, considered collectively.
Origin
Early 20th century. From German Pleuston from ancient Greek πλευστέον necessity of sailing, after German Plankton, Nekton.