Long Term Effects of Climate on Two Pond Predators

Abstract

This study assessed the influence of annual snowpack on long term changes in the predatory regime of four high elevation ponds in the mountains of northwest Wyoming. Over 36 y of observation, in two ponds the primary predator alternated between phantom midge Chaoborus americanus larvae and Diaptomus shoshone predatory copepods, whereas the predatory regime did not change in the other two shallower ponds. Switching of predators correlated with extreme amounts of winter snow, either high or low, which determined the depth at which drying or complete freezing of the pond occurred. Chaoborus americanus colonized ponds after the wettest years and disappeared after the driest years. The results provide an unusual long term perspective of the effects of weather on predator dominance.