The Mobile Basin is a prime example of a system that has undergone extensive channel modification with corresponding declines in the distribution and abundance of the native aquatic fauna. However, many of the declining aquatic species of the Mobile basin may persist within unmodified subbasins. The Noxubee River is a subbasin of the Mobile basin that has had very little alteration throughout its watershed. I investigated the species richness and assemblage structure to determine if the contemporary fish assemblage attributes resembled the conditions represented by historic collections. The findings of this study are important because the Noxubee River has not been extensively investigated since 1983, and the river could serve as refugia for declining riverine species of the Mobile basin. After examination at both local and regional levels, I determined that a diverse contemporary fish assemblage comprising 87 species, similar to historic collections, still persists in the Noxubee River system.

The deluxe, comprehensive guide to the native species of Mississippi Download Plain Text version Where was the largest bass caught in Mississippi? What streams are sometimes home to the gulf sturgeon? How can an angler tell a grass pickerel from a walleye? In Inland Fishes of Mississippi, Stephen T. Ross answers these questions and many more. Mississippi waters are some of the richest inland fish habitats in the United States. In fact, only four states have more native fish than Mississippi's 204. Inland Fishes of Mississippi is for anglers and nature lovers who want to learn more about this thriving diversity. Introductory chapters present the history of the study of fish in Mississippi, the distribution patterns of species, important conservation issues, and valuable information on identifying fish by examining body shape and structure. Following these are illustrated keys to all the families of fish known to inhabit inland waters. Each key is a detailed guide to identifying the specific species within a family of fish. Keys include: color photographs of freshly collected examples meanings of scientific names for fish descriptions of color and physical changes maximum sizes of fish, including records for game fish precise maps of distribution vital information on habitat requirements, feeding, and behavior tips on where to catch a species status of conservation efforts For both the casual angler and the ichthyologist, Inland Fishes of Mississippi will prove a constant resource and an irreplaceable asset for identifying, observing, and catching the state's various species. Stephen T. Ross is professor of biological sciences and Curator of Fishes at the University of Southern Mississippi. The editor for ecology and ethology of Copeia, he has also published articles in numerous journals such as American Naturalist, Environmental Biology of Fishes, and Transactions of the American Fisheries Society.

In rivers that shift in their natural or modified physical structure, it is expected that organisms alter their resource use with the shifts in physical changes. The Upper Mississippi River System (UMRS) is a modified river basin and stark contrasts in both the physical structure of habitat types and biological structure in the types of organisms present exist spatially. The upper reaches of the basin contain more complex habitat types than the lower reaches which suggests resource use of fishes likely differs at least between upper and lower reaches. To date, the resource use of some commercially important, invasive, and imperiled species has been studied. However, little information regarding resource use exists for most native fishes. Understanding resource use and how it differs across time and space would benefit managers of the UMRS as programs are underway to restore and manage the system. To determine how resource use of native fishes differs spatially and temporally in the UMRS, I quantified resource use of ten native fishes across six reaches of the UMRS using multiple techniques. At the largest spatial and temporal scale, I quantified the natal origins of six prey and two predatory fishes using trace element analysis. At a seasonal scale, I quantified the collective resource use of eight species using carbon and nitrogen isotopes to compare isotopic niche space, niche overlap, and community metrics. At the shortest scale, I quantified the diets of two predatory species that are thought to compete with one another. Both large scale similarities and nuances in resource use existed in the UMRS depending on the spatial and temporal contexts. At the longest scale, fishes consistently used network connectivity as tributaries and other mainstem river reaches contributed recruits to the mainstem river. However, the percentage of individuals resulting from network connectivity and the specific rivers that lent the recruits differed among species and reaches. Particularly, large tributaries like the Minnesota and Missouri rivers contributed relatively high numbers of recruits to nearby reaches compared to other tributaries, and the most downstream reaches had the greatest contributions from network connectivity. Prey fishes recruited more often from tributaries than predators whereas consumed prey and prey collected directly from the UMRS had similar origins which were consistent across years. At a seasonal scale, breadth of resource use of individual species and the assemblage and some community metrics increased whereas overlap decreased moving downstream in the UMRS. This shift in resource use metrics coincides with shifts in the physical structure of the system. At the shortest scale, diet compositions of the two predators were similar to one another and spatially among upper reaches in the UMRS. These two predators likely coexist in part due to diet plasticity and prey size allocations that differ between species. Additionally, the relative physical homogeneity of the upper reaches of the UMRS may have led to the spatial similarity in prey use. Together, these results suggest the physical structure of the system impacted the resource use of fishes, where trophic niches and use of network connectivity shifted with the shift in physical structure of the Mississippi River. At a minimum, spatial gradients in isotopic niches and percentage of individuals coming from network connectivity suggest the resource use of fishes in downstream reaches at seasonal and life-long scales differs from the upstream reaches within this system. These differences could stem from longitudinal or functional process zone shifts in the physical structure which cannot be determined given these data. In the context of management of the system, fishes use network connectivity to at least some degree across all species and sampling reaches, indicating that the connectivity in the system should at least be maintained if not improved. Additionally, fish move among reaches (i.e., through lock and dams) and tributaries, which highlights the need for interjurisdictional management not just in the UMRS but in nearby tributary systems like the Minnesota and Missouri River where fish originated.

We investigated differences in adult and young-of-the-year (YOY) fishes within each of the six Long Term Resource Monitoring Program study areas, using monitoring data from 1993 to 2001. Our objective was to investigate the relative roles of seasonal, annual, in situ, and physical habitat factors in explaining assemblage structure patterns within the Long Term Resource Monitoring Program study areas. Adult and YOY assemblage structure within each reach was dominated by one to three numerically abundant species. The percent of the total abundance for which these species accounted was 10-88% and varied among age classes and study areas. Physical habitat classes were only weakly associated with differences in fish assemblage patterns within each study area. The amount of variation in fish abundance explained by physical habitats varied among the reaches. Differences among physical habitat classes accounted for 3-23% of the variation in the adult fish assemblage and for 3-20% of the difference in the YOY fish assemblage within each reach of our study area. Factors associated with interannual differences in environmental conditions were strongly correlated to patterns in assemblage structure within each of the six study areas. This was particularly true for YOY assemblages. Such a result would not have been attainable without long-term standardized data. Little is known regarding YOY assemblage patterns and dynamics in large river systems and long-term data sets are vital for continued investigation. The influence of environmental gradients on fish assemblage structure varied among the six study areas and explained 9-31% of the variation in assemblage structure. In the northern four reaches, water velocity was one of the primary factors associated with differences in fish assemblage structure. In the Unimpounded Reach (Upper Mississippi River) and Illinois River study areas, river elevation was one of the primary factors associated with differences in assemblage structure. Depth of gear deployment was influential in explaining differences in assemblage structure patterns in all reaches except the Upper Mississippi River Pool 4 and the Illinois River study areas. In all study areas, the amount of variation in fish abundance patterns explained by sampling period was relatively low. However, assemblage structure differed among sampling periods. In the northern reaches, sampling periods 2 and 3 were the most similar.