, 2009). More tolerant fish species, such as white perch (Morone americana) and yellow perch also altered their diets to consume more zooplankton in response to hypoxia, but these shifts were more subtle ( Roberts et al., 2009 and Roberts et al., 2012). Finally, these species-specific distributional and foraging responses to hypoxia are generally supported by seasonal trends in fish condition in CB. While condition of emerald shiner improved from summer into fall, rainbow smelt condition declined during hypoxia (Ludsin et al. unpublished). Condition of tolerant yellow perch in Lake Erie did not decrease during

the height of hypoxia ( Roberts et al., 2009) and yellow perch RNA:DNA ratios (an index of short-term condition)

did not reveal a selleck chemical strong negative response to hypoxia ( Roberts et al., 2011). While empirical evidence points to a variety of taxon-specific negative and positive effects of hypoxia on fish feeding, growth, and production in Lake Erie, the magnitude of such potential effects and their population-level consequences remain open questions. Through the Ecofore-Lake Erie program, we have explored such effects through a variety of models. Given the variety of pathways through which hypoxia may affect fish vital rates, models differ in their relative emphasis on diverse processes. The simplest and most straightforward approach has consisted of developing statistical relationships between measures of hypoxia and fish population metrics at the lake-basin scale. For example, we found a significant negative relationship between the number of modelled hypoxic (DO ≤ 2 mg/l) selleck chemicals llc days and the condition (elative-weight based) of both mature (2 +) female and male yellow perch captured in the CB during fall (September–October) 1990–2005 (Fig. 8), suggesting that observed distributional and foraging responses at hypoxic CB sites during summer (Roberts et al., 2011)

may have until population-level impacts. Brandt et al. (2011) and Arend et al. (2011) modeled growth rate potential (GRP) of selected fishes in the CB as a surrogate for fish habitat quality. Brandt et al. (2011) argued that hypoxia had a temporary positive effect on walleye (Sander vitreus) GRP as prey fish were forced into areas where temperature, DO, and light conditions were favorable for efficient walleye foraging and growth. In contrast, Arend et al. (2011) found that GRP of yellow perch, rainbow smelt, emerald shiner, and round Goby (Neogobius melanostomus) improved with reductions in P loading and hypoxia prior to the mid-1990s, but did not continue to improve from the mid-1990s through 2005 (and may even have decreased). Arend et al. (2011) also showed that hypoxia impacts were most severe for adult stages of non-native species, including cold-water rainbow smelt and round Goby, a benthic species that typically forages on the lake bottom.