Replacement analysis of non-equilibrium competition between rock pool Corixids (Hemiptera, Corixidae).

The resource use of rock pool Corixids Arctocorisa carinata (Sahlb.) and Callicorixa producta (Reut.) was compared in single-species and mixed populations established in the natural environment. The experimental recruitment consisted of daily transfer of newly moulted first-stage larvae to the study pools. The changes in numbers of larvae and the increase of the biomass corresponded closely to the changes in natural populations. The growth of populations was limited by elimination of the youngest individuals. The maximal biomasses attained per unit of pool surface area were same in all cases. This indicates that the species have completely overlapping resources and use them with nearly equal efficiency. The strong interference by A. carinata is an additional reason for the unstability of the competitive interaction.