Intentional Fragmentation as a Management Strategy in Aquatic Systems

Rhine–Main–Danube Canal, which resulted in a massive biotic exchange between the Rhine and Danube drainages (Rahel 2007, Leuven et al. 2009). Less clear cut are situations that involve restoring connectivity in waterways that were historically connected or fragmenting currently connected systems (Fausch et al. 2009, Jackson and Pringle 2010). In fact, maintaining isolation or even intentionally fragmenting systems may be beneficial. The benefits fall into four main categories: preventing the spread of nonnative species, preventing the spread of exotic diseases, preventing hybridization between hatchery and wild populations, and preventing organisms from entering attractive human-created habitats that act as ecological traps. Therefore, natural resource managers face a tension in balancing the pros and cons of connectivity in aquatic systems (figure 1).