Experimental Venue and Estimation of Interaction Strength

Ecologists utilize laboratories, mesocosms, and field environments as the settings for their experiments. However, the ways in which these venues influence experimental outcomes remain poorly understood. I tested the effect of experimental venue by conducting parallel manipulations in mesocosms and in the field. A target-neighbor experiment estimating the impact of larval wood frog (Rana sylvatica) density on the performance of spring peeper (Pseudacris crucifer) larvae was carried out in a set of artificial pond mesocosms and within mesh enclosures placed in natural ponds. Larvae of P. crucifer suffered sharp reductions in growth and development in the presence of increasing R. sylvatica densities when reared in mesocosms, but showed no response in field enclosures. A comparative test suggested that mesocosms yielded relatively unrealistic responses. These findings demonstrate that, apart from other considerations such as spatial scale, experimental venue can alter conclusions regarding interactions between species. If venue dependence is widespread, ecologists will need to strategically assess the choice of venue when considering the goals of their experiments.