Coupled physical-chemical-biological models to predict losses of cold-water fish from inland lakes under climate warming

Cold-water fish are disappearing from many midwestern lakes as they warm. This loss is due to a combination of de-oxygenation of the deep waters with heating of the surface waters. Together, these climate-driven changes squeeze the depth distribution of fish that require cold, well-oxygenated water, sometimes eliminating their habitat entirely. We will investigate where this combination of factors has likely caused extirpation of cold-water fishes, and where future warming is most likely to eliminate more populations. In addition to hydrodynamic modeling, we are partnering with genomics experts to assess selection on functional genes associated with surviving temperature or oxygen challenges.

The goals of this project are to:

• Manage cold-water lake fishes.
• Manage fish species of special concern in the state.
• Guide pre-emptive efforts to prioritize sites for management interventions.

Collaboration launched with Midwest Glacial Lakes Partnership and USGS Wisconsin Co-Op Fisheries Unit to analyze natural selection on immune system and thermal stress genes in cold-water fish at risk of extirpation across Indiana, Wisconsin, Minnesota, and Michigan. There is both strong population genomic structure in these inland lake cisco, and wide differences in genetic diversity and effective population sizes. Moreover, we have found extensive variation in the MHC immune system genetic diversity across populations. We have now completed physical modeling, and are in the process of consolidating both perspectives.