While a GRP modeling approach offers a more mechanistic means than linear regression to estimate target nutrient loads, this approach is static, and hence, cannot account for the likely feedbacks and indirect effects that might exist as temperature and hypoxia vary through space and time. For example, behavioral avoidance of hypoxia has been shown to lead to highly dynamic predator–prey interactions

and density-dependent growth, and these changes in predator–prey interactions can cascade to not only affect a single predator–prey pair, but also the entire food web. Thus, we also have been exploring the effects of hypoxia and other habitat attributes (e.g., temperature, prey availability) on fish using more dynamic approaches, such as individual- and population-based bioenergetics simulations (individual-based TGF-beta inhibitor modeling; D. Goto, personal communication), fish population behavior (patch-choice modeling; K. Pangle, personal communication), trophic interactions (Ecopath with Ecosim; e.g. Langseth et al., 2012), and comprehensive ecosystem responses (Comprehensive Aquatic Systems Modeling, CASM;

e.g. Bartell, 2003). These modeling approaches differ greatly in their spatial and temporal resolution and focus on the entire foodweb versus a subset of abundant, representative species. The differential emphasis on behaviorally mediated habitat selection, trophic interactions and trophic cascades among these models may lead to somewhat dissimilar predictions regarding ecological effects of hypoxia in Lake Erie. The integration learn more Erastin solubility dmso of output from these diverse modeling approaches collectively provide a suite of plausible forecasts, as well as by help to identify key uncertainties that can guide future monitoring and research decisions. Because

of increases in hypoxia since the mid-1990s and because other eutrophication symptoms and potential impacts have become stronger since then, consideration of new phosphorus loading targets seems warranted. The use of models to assist in developing nutrient loading targets for the Great Lakes has a long history. Bierman (1980) reviewed their use as part of the negotiation of the earlier GLWQA, at which time five models were used to develop P loading objectives. The models ranged from simple, empirical correlations to complex mechanistic models (Bierman and Dolan, 1976, Bierman et al., 1980, Chapra, 1977, DiToro and Connolly, 1980, DiToro and Matystik, 1980, Hydroscience, 1976, Thomann et al., 1975, Thomann et al., 1976 and Vollenweider, 1977). Since that time, a variety of biogeochemical models have been developed to understand ecological interactions within Lake Erie and other Great Lakes. While some models were constructed during the 1980s (e.g., DePinto et al., 1986c, Di Toro et al., 1987, Lam et al., 1987a, Lam et al.