Do Reservoirs Facilitate Invasions into Landscapes?

TLDR

Reservoirs, created by dam construction, have become widespread standing freshwater habitats that act as stepping‑stones, facilitating the dispersal of exotic species across fragmented landscapes. The authors hypothesize that reservoirs are more susceptible to invasion than natural lakes because of their altered physicochemical conditions, increased connectivity, and disturbance, and they link river flow manipulation to the accelerating spread of exotic species. They summarize reservoir properties—such as altered flow regimes, nutrient enrichment, and connectivity—that predispose them to invasions and provide examples of reservoirs that have accelerated range expansion.

Abstract

The extensive construction of reservoirs over the past century has radically altered the environmental landscape on a global scale. Construction of dams on most large rivers has interrupted the connectivity of water flow and greatly increased the abundance of standing freshwater habitats. Reservoirs act as stepping-stones for the dispersal of exotic species across landscapes. A variety of passively dispersing species have invaded reservoirs, spread through interconnected waterways, and been transported to nearby disconnected habitats. We hypothesize that reservoirs are more readily invaded than natural lakes, because of their physiochemical properties, greater connectivity, and higher levels of disturbance. Here we summarize properties of reservoirs that would make them prone to invasions and discuss cases in which reservoirs have facilitated rapid range expansion. Our overview illustrates linkages between two important forms of global environmental change: the widespread manipulation of river flows and the accelerating spread of exotic species.