Aquatic Habitat Fragmentation: Barrier to Native Species Conservation or Invasive Species?

Habitat degradation and aquatic invasive species are the two greatest threats to freshwater species at risk in North America. These threats act synergistically with each other and other threats, often resulting in complex management scenarios. Habitat fragmentation, as a result of damming or other habitat degradation, may directly threaten freshwater species by disrupting metapopulation dynamics. Conversely, such fragmentation may reduce the interactions between native and invasive species by maintaining a separation in their distributions. However, habitat fragmentation may facilitate colonization of degraded or new habitats (e.g. reservoirs) by invasive species. The nature and extent of these interactions, and the management actions required to address them, are species and location dependent. The complexities of these species interactions and management actions will be explored using native and invasive fish and mussel species in the Grand River, Ontario as a case study.