Dissolved Oxygen Tolerance Guilds of Adult and Juvenile Great Lakes Fish Species

Habitat suitability matrices (HSM) for calculating habitat supply have long been an irreplaceable tool in fish habitat assessments. A key component in HSM is defining fish guild assemblages. We selected dissolved oxygen (DO) tolerance as the essential factor to characterize fish guild assemblages for fish habitat assessments in the Great Lakes. Hypoxia is a form of habitat loss that can cause physiological stress on fish and lead to widespread mortality and changes in fish community assemblages. To determine 'sensitive,' 'mesotolerant,' and 'tolerant' DO tolerance guilds for Great Lakes fish species, we conducted a one-dimensional k-means cluster analysis using mean DO tolerance levels extracted from the literature. To verify our 'HABLAB' results, we assigned confidence values to our classifications based on a weight of evidence approach. Our results were further refined by combining with other known indices of general and DO fish tolerances (Barbour et al. 1999; Meador and Carlisle 2007; Trebitz et al. 2007; Eakins 2019) using a weighted average approach (Method 1) and a majority rule approach (Method 2). The final guild classification was decided using a decision tree, which took into account a combination of the lines of evidence provided by our HABLAB dataset and other reported tolerance indices. Of the 164 Great Lakes freshwater fish species considered in this study, 43 (27%), 81 (50%), and 20 (12%) species were assigned to the sensitive, mesotolerant, and tolerant guilds, respectively. To our knowledge, this study is the first to use a weight of evidence approach incorporating summarized information from literature and existing guild classification in sorting DO tolerance fish guilds. The results from this study can further provide a foundational framework to inform future fish habitat assessments in the Great Lakes.