Just add water: rapid assembly of new communities in previously dry riverbeds, and limited long-distance effects on existing communities

Abstract

Barriers preventing species from dispersing to a location can have a major influence on how communities assemble. Dispersal success may also depend on whether dispersers have to colonise an established community or a largely depauperate location. In freshwater systems, dams and weirs have fragmented rivers, potentially limiting dispersal of biota along rivers. Decommissioning aqueducts on two weirs, each within a tributary of different regulated rivers, delivered flow to previously dry riverbeds and additional flows to the main stem, regulated rivers further downstream. This provided an opportunity to test how removal of dispersal constraints affected community assembly in new habitats and w..