Extinction Debt of Fishes in Great Lakes Coastal Wetlands

Session: Imperiled Species in the Great Lakes Basin: Identifying Threats and Restoring Populations (2)

Fielding Montgomery, University of Toronto, [email protected]
Scott Reid, Ontario Ministry of Natural Resources, [email protected]
Nicholas Mandrak, Biological Sciences, University of Toronto Scarborough, [email protected]

Abstract

Declines in North American freshwater biodiversity can be largely attributed to anthropogenic disturbances. Anthropogenic disturbances can reduce habitat quantity, quality, and connectivity. Extinction-debt theory suggests that species will exhibit a time-lag between habitat loss and local extinction. Laurentian Great Lakes wetlands have been significantly lost as a result of agricultural land-use practice, yet high species richness and several at-risk fishes persist. We tested the hypothesis that fishes of Great Lakes coastal wetlands, specifically unprotected wetlands, are in extinction debt using species-area curves. Species richness was significantly higher than expected in unprotected wetlands, indicating that the fishes in them are in extinction debt. We identified 17 wetlands of high priority for conservation and restoration, which contained eight at-risk fishes. We determined how much area was required to support current species richness and compared this to minimum area requirement for eight at-risk fishes. Evidence of extinction debt suggests that there is still time to restore disturbed wetlands and prevent local extinction. Our results indicate that the restoration of 178 km² of wetland habitat would reduce the risk of further biodiversity loss. Extinction-debt assessments in aquatic systems are needed to extend the ecological theory and fundamental application of extinction debt beyond terrestrial systems.