There are a number of organisms in nature that live just above or below the surface film, collectively called the neuston (pronounced “noo-stun”). No doubt you are familiar with several of the larger neuston, like water striders or duckweed. There are also many microscopic species that live at the surface.

Some neuston spend only a part of their lives in the surface film, as either larvae or as eggs. Others will live their entire life at or around the surface. These organisms may live above the surface film, supported by the surface tension, or they may live below, hanging from the surface tension. Adaptations of the neuston include spindly legs, water repellant bodies, light weight, “hairy” feet, etc. The neuston living below the surface may have adaptations that, not unlike a coat hanger, allow the organism to suspend itself from the surface film.

Neuston are adapted to take advantage of the higher concentrations of organic matter found in the “surface scum”. Some algae species thrive in the nutrient and sun-rich surface film. The larger neustonic organisms typically consume the smaller neuston that are “eating” in the surface film.

There’s a lot going on in the lake’s top eighth of an inch. That’s why you should always skim the surface of the water and make sure your bottle goes well under the surface when sampling. We don’t want to misrepresent the lake by inadvertently sampling this nutrient and microbe-rich surface layer. Keep the neuston out of the sample bottle!

Tony Thorpe

Brought to you by the Lakes of Missouri Volunteer Program