Pollen as food: effects of consumption on tadpole growth, development, and mobility

The structure of many aquatic food webs is influenced by tadpole survivorship and duration of seasonal occupancy, which depend on tadpole diet. Pollen has been occasionally reported to occur in tadpole diets, and the available studies show that tadpoles have a strong preference for this supposedly nutritive resource. Thus, we aimed to test whether a diet composed of pollen from varied plant species would boost tadpole growth, development, and agility/mobility, compared to a regular artificial balanced and nutritive diet. Tadpoles in initial developmental stages 25 and 30 grew more when fed with pollen, compared to artificial food and a mixture of both diets. Those initially in stage 30 advanced more developmental stages during one month when fed exclusively with pollen. Tadpoles fed with pollen moved longer distances in response to an aversive stimulus simulating a predatory attack than tadpoles fed with artificial food or a mixed diet. Our results corroborate the hypotheses of pollen being a very important food source to aquatic consumers such as tadpoles, being likely to influence the structure of aquatic food webs through tadpole nutrition and modulation of growth/development speed, as well as tadpole ability to escape predators.