Spatial averaging and disturbance lead to high productivity in aquatic metacommunities

Dispersal in heterogeneous ecosystems, such as coastal metacommunities, is a major driver of diversity and productivity. According to theory, both species richness and spatial averaging shape a unimodal relationship of productivity with dispersal. We experimentally tested the hypothesis that disturbances acting on local patches would buffer the loss of productivity at high dispersal by preventing synchronized species oscillations. To simulate these disturbances, our experimental assemblages involved species that self-organized in isolation under three inflow pulsing frequencies, where hydraulic displacement and nutrient loading affected assemblage diversity and composition. At steady-state, the emerging isolated assemblages were connected at three levels of dispersal creating three metacommunities of different connectivity. Consistent with theory, as dispersal increased, species richness in the metacommunity declined; productivity however remained high. This occurred because the most pr...