The effect of tadpoles on algal growth in temporary, rain-filled rock pools

SUMMARY.

• 1 Small, temporary, rain-filled rock pools in Malawi, Central Africa, are colonized by algae, insect larvae and tadpoles. Algal growth in these pools is largely controlled by nutrient supply, flushing rate and the presence of tadpoles.
• 2 Dissolved nitrogen and phosphorus concentrations were usually high following filling but subsequently declined. Nitrogen supply may limit algal growth at times. The flushing rate of the pools is an over-riding factor in determining the population size of floating algae.
• 3 Experiments and field observations showed that tadpoles apparently, paradoxically, promoted the growth of the epineustic and phytoplanktonic algae on which they grazed. The explanation of this paradox probably has in the transfer, by the tadpoles, of nutrients from the sediments to the overlying water. This nutrient enrichment stimulates the growth of the epineuston and phytoplankton.