Forecasting Effects of Climate and Land-Use Change On Lake Erie's Central Basin Fish

Continued increase of global temperatures will have important consequences for aquatic habitats and lake stratification dynamics. Higher temperatures will shift optimal habitats and cause stratification to develop earlier with a thicker thermocline. In the central basin of Lake Erie, these factors will likely increase the duration, extent, and severity of seasonal hypolimnetic hypoxia. Moreover, nutrient inputs from surrounding agricultural land may exacerbate these climate-induced effects. We used hydrodynamic and limnological models to drive a 1-dimensional, spatially-explicit, individual-based model to forecast effects of future land-use and climate on walleye, yellow perch, rainbow smelt, and emerald shiner. A warmer epilimnion, combined with severe hypolimnetic hypoxia, created an oxy-thermal squeeze that compressed vertical distributions as fish avoided both sub-optimal thermal and oxic environments. Higher nutrient levels increased hypoxia, further aggravating vertical distribution compression. Concentration of prey fish increased production of predators to a point. However, some scenarios became sufficiently inhospitable so as to indicate exclusion of our focal species from the central basin. Benefits of increased zooplankton prey generated by increased nutrients were generally obscured by concomitant worsening of hypoxia and increased temperatures. Our results demonstrate the difficulty in balancing future agricultural and fisheries production in the context of climate change.