Multiple anthropogenic forces have pushed river ecosystems into undesirable states with no clear understanding of how they should be best managed. The advancement of riverine fish habitat models intended to provide management insights has slowed. Investigations into theoretical and empirical gaps to define habitat more comprehensively across different scales and ecological organizations are crucial in managing the freshwater biodiversity crisis. We introduce the concept of novel riverscapes to reconcile anthropogenic forcing, fish habitat, limitations of current fish habitat models, and opportunities for new models. We outline three priority data-driven opportunities that incorporate the novel riverscape concept: fish movement, river behavior, and drivers of novelty that all are integrated into a scale-based framework to guide the development of new models. Last, we present a case study showing how researchers, model developers, and practitioners can work collaboratively to implement the novel riverscape concept.

This study examines the impact of boldness on foraging competition of the highly invasive round goby Neogobius melanostomus Pallas 1815. Individual risk tolerance, or boldness, was measured as the time to resume movement after a simulated predation strike. Fish that resumed movement faster were categorized as "bold," fish that took more time to resume movement were categorized as "shy" and those that fell in between these two categories were determined to have "intermediate" boldness. Competitive impacts of boldness in N. melanostomus were determined in a laboratory foraging experiment in which interspecific (juvenile Atlantic cod Gadus morhua Linnaeus 1758) and intraspecific (intermediate N. melanostomus) individuals were exposed to either bold or shy N. melanostomus competitors. G. morhua consumed fewer prey when competing with bold N. melanostomus than when competing with shy N. melanostomus, whereas intermediately bold N. melanostomus foraging was not affected by competitor boldness. Bold and shy N. melanostomus consumed similar amounts of prey, and the number of interactions between paired fish did not vary depending on the personality of N. melanostomus individuals. Therefore, intraspecific foraging competition was not found to be personality dependent. This study provides evidence that individual differences in boldness can mediate competitive interactions in N. melanostomus; nonetheless, results also show that competition is also governed by other mechanisms that require further study.

Differences between individuals in behavioral type (i.e. animal personality) are ecologically and evolutionarily important because they can have significant effects on fitness components such as growth and predation risk. In the present study we are used the invasive round goby (Neogobius melanostomus) from an established population in controlled experiments to examine the relationships among personality, metabolic performance, and growth rate (inferred as size-at-age). Boldness was measured as the time to return to normal behavior after a simulated predator attack, where fish with shorter freezing times were categorized as "bold" and fish with longer times were categorized as "shy." We show that bold fish have significantly higher standard metabolic rate (SMR) than their shy conspecifics, whereas there was no difference between personality types in their maximum metabolic rate (MMR) or aerobic scope (AS). Bold fish furthermore had a smaller size-at-age as compared to shy fish. Together this provides evidence of a metabolic underpinning of personality where the high-SMR bold fish require more resources to sustain basic life functions than their low-SMR shy conspecifics, indicating that bold round goby from established populations with high densities (and high competition for food) pay a price of reduced growth rate.

Invasive species are currently one of the main causes of biodiversity loss across the globe and recent research has shown that the personality of an invader can have significant impacts on the invasion dynamics for that species. Therefore, this study examined the impact of personality on both competitive success and predation susceptibility of the highly invasive round goby (Neogobius melanostomus). Boldness was measured as the time to return to normal behavior after a simulated predation strike. Fish with shorter panic times were categorized as “bold”, fish with longer times were categorized as “shy”, and those who fell in between these two categories were determined to be “intermediate”. Competitive impacts of personality were determined in a laboratory experiment in which intra- (intermediate round goby) and interspecific (juvenile Atlantic cod, Gadus morhua) competitors were exposed to both bold and shy round goby competitors. Predation susceptibility of bold and shy personality-type round gobies was determined in a predator preference experiment. Results from the competition experiment showed that interspecific competitors consumed fewer prey when competing with bolder round gobies than when competing with shy round gobies. Bold and shy treatment gobies consumed similar amounts of prey, and the number of interactions between competitors did not vary depending on the personality of the treatment round goby. Results from the predation experiment indicated a trend of increased susceptibility to predation by adult Atlantic cod for bold round gobies over shy round gobies, but it was not statistically significant. These results show that personality mediates competitive interactions within the round goby, and suggests that the high proportions of bold individuals found along invasion fronts in this species may have stronger-than-population-average impacts on native communities, potentially facilitating the further invasion of the round goby. (Less)