Jon M Vallazza
Science and Products
Influence of a high-head dam as a dispersal barrier to fish community structure of the Upper Mississippi River
In river systems, high‐head dams may increase the distance‐decay of fish community similarity by creating nearly impermeable dispersal barriers to certain species from upstream reaches. Substantial evidence suggests that migratory species are impacted by dams, and most previous studies in stream/river networks have focused on small streams and...
Anderson, Rebekah L.; Anderson, Cory A.; Larson, James H.; Knights, Brent C.; Vallazza, Jon; Jenkins, Sean E.; Lamer, James T. Estimating the degree to which distance and temperature differences drive changes in fish community composition over time in the upper Mississippi River
Similarity in community composition declines as distance between locations increases, a phenomenon that has been observed in a wide variety of freshwater, marine and terrestrial ecosystems. One driver of the distance-similarity relationship is the presence of environmental gradients that alter the suitability of sites for particular species....
Larson, James H.; Vallazza, Jon; Knights, Brent C. Evaluating potential effects of bigheaded carps on fatty acid profiles of multiple trophic levels in large rivers of the Midwest, USA
Recent work indicates that the establishment of bigheaded carps (Hypophthalmichthys spp.) in the United States has led to a reduction in condition of native planktivores and may detrimentally affect other trophic levels by altering the base of aquatic food webs. We used fatty acids to evaluate potential effects of bigheaded carps on taxa from...
Fritts, Andrea; Knights, Brent C.; LaFrancois, Toben; Vallazza, Jon; Bartsch, Lynn A.; Bartsch, Michelle R.; Richardson, William B.; Bailey, Sean; Kreiling, Rebecca; Karns, Byron Spatial and temporal variance in fatty acid and stable isotope signatures across trophic levels in large river systems
Fatty acid and stable isotope signatures allow researchers to better understand food webs, food sources, and trophic relationships. Research in marine and lentic systems has indicated that the variance of these biomarkers can exhibit substantial differences across spatial and temporal scales, but this type of analysis has not been completed for...
Fritts, Andrea; Knights, Brent C.; Lafrancois, Toben D.; Bartsch, Lynn A.; Vallazza, Jon; Bartsch, Michelle R.; Richardson, William B.; Karns, Byron N.; Bailey, Sean; Kreiling, Rebecca Using pharyngeal teeth and chewing pads to estimate juvenile Silver Carp total length in the La Grange Reach, Illinois River
The Silver Carp Hypophthalmichthys molitrix is an invasive species in the Mississippi River basin; an understanding of their vulnerability to predation as juveniles may inform control by native predators and predator enhancement (e.g., stocking). Digestion of Silver Carp prey recovered from diets makes it difficult to determine the size‐...
Lampo, Eli G.; Knights, Brent C.; Vallazza, Jon; Anderson, Cory A.; Rechkemmer, Will T.; Solomon, Levi E.; Casper, Andrew F.; Pendleton, Richard M.; Lamer, James T. Evidence of Asian carp spawning upstream of a key choke point in the Mississippi River
Bighead Carp Hypophthalmichthys nobilis, Silver Carp H. molitrix, and Grass Carp Ctenopharyngodon idella(collectively termed “Asian carp”) were introduced into North America during the 1960s and 1970s and have become established in the lower Mississippi River basin. Previously published evidence for spawning of these species in the...
Larson, James H.; Knights, Brent C.; McCalla, S. Grace; Monroe, Emy; Tuttle-Lau, Maren T.; Chapman, Duane C.; George, Amy E.; Vallazza, Jon; Amberg, Jon J. Using a gradient in food quality to infer drivers of fatty acid content in two filter-feeding aquatic consumers
Inferences about ecological structure and function are often made using elemental or macromolecular tracers of food web structure. For example, inferences about food chain length are often made using stable isotope ratios of top predators and consumer food sources are often inferred from both stable isotopes and fatty acid (FA) content in consumer...
Larson, James H.; Richardson, William B.; Vallazza, Jon; Bartsch, Lynn A.; Bartsch, Michelle R. Effects of food resources on the fatty acid composition, growth and survival of freshwater mussels
Increased nutrient and sediment loading in rivers have caused observable changes in algal community composition, and thereby, altered the quality and quantity of food resources available to native freshwater mussels. Our objective was to characterize the relationship between nutrient conditions and mussel food quality and examine the effects on...
Bartsch, Michelle R.; Bartsch, Lynn A.; Richardson, William B.; Vallazza, Jon; Moraska Lafrancois, Brenda Spatial and temporal dynamics of suspended particle characteristics and composition in Navigation Pool 19 of the Upper Mississippi River
Suspended particles are an essential component of large rivers influencing channel geomorphology, biogeochemical cycling of nutrients, and food web resources. The Upper Mississippi River is a large floodplain river that exhibits pronounced spatiotemporal variation in environmental conditions and biota, providing an ideal environment for...
Milde, Amanda S.; Richardson, William B.; Strauss, Eric A.; Larson, James H.; Vallazza, Jon; Knights, Brent C. Genetic analysis shows that morphology alone cannot distinguish asian carp eggs from those of other cyprinid species
Fish eggs and embryos (hereafter collectively referred to as “eggs”) were collected in the upper Mississippi River main stem (~300 km upstream of previously reported spawning by invasive Asian carp) during summer 2013. Based on previously published morphological characteristics, the eggs were identified as belonging to Asian carp. A subsample of...
Larson, James H.; McCalla, S. Grace; Chapman, Duane C.; Rees, Christopher B.; Knights, Brent C.; Vallazza, Jon; George, Amy E.; Richardson, William B.; Amberg, Jon J.