pleuston

/ˈpluːstɑn/
noun
  1. Small organisms that live floating on or just below the surface of a body of water.
    • The pond's surface was covered with pleuston, including tiny water ferns and floating algae.
    • Scientists study pleuston to understand how life adapts to living at the water-air boundary.
    • Dragonfly larvae are sometimes part of the pleuston community in calm lakes.