Daphniids avoid Utricularia on a horizontal plane

Marcin T. Mazurkiewicz, Barbara Płaskonka, Marta Galas, Marta Kret, Barbara Pietrzak 

Besides animal predators, carnivorous plants, such as the littoral bladderwort Utricularia vulgaris, also strongly impact cladoceran communities by efficiently capturing passing planktonic animals, including small daphniids, in their bladder traps. Therefore, we hypothesized these animals should avoid direct contact with these carnivorous plants. We measured the distance Ceriodaphnia and small-bodied Daphnia keep from plants in both a horizontal and a vertical setup. Predatory plant Utricularia, non-predatory coontail Ceratophyllum, or an artificial plant were placed in either bladderwort conditioned water or control medium. The measurements performed in the horizontal setup showed that the studied daphniids stayed further away from predatory bladderwort than from the non-predatory plant and further from an artificial plant in bladderwort conditioned water than in control water. Thus, our results suggest that by this behavioural avoidance cladocerans navigate through the even more complex than previously thought landscape of fear - that of planktivorous fish, invertebrate predators, and now also evidenced plant predators.