Watersprites

A Watersprite is a magical creature that comes from the general Sprite family. Like Woodsprites or Firesprites, these creatures are tied to their elemental foundations and can harness the power of water.

Mainstream Smurfs Media
Two Watersprites have been featured in separate episodes of the Smurfs cartoon show, starting in "Bubble, Bubble, Smurfs in Trouble," where Dewey is introduced with Scaredy Smurf and allows him to use his magic impenatrable bubble for safety until dusk.

Later on in another episode, an unnamed female Watersprite is startled by the Smurfs when they go to the beach, so she turns Smurfette into a mermaid.