Changes in Fish Assemblage Structure Upstream of Impoundments within the Upper Wabash River Basin, Indiana

Abstract

The effects of dams and impoundments on downstream fish assemblages have been well documented, but changes in fish assemblages in upstream tributaries have received little attention. We compared changes in abundance and composition in fish assemblages in streams fragmented by impoundments with those found in nearby unfragmented streams by sampling fish, in‐stream habitat, physicochemical factors, and drainage features in 22 agriculturally dominated streams during the summers of 2002 and 2003. Eleven sampling sites were tributaries upstream of impoundments, while 11 were tributaries of free‐flowing rivers. We tested the hypothesis that fish assemblages upstream of impoundments would differ from those found in streams without impoundments. Using multiple regression and canonical correspondence analysis, we partitioned the variation in species distributions into that explained by in‐stream habitat, reach‐level factors, drainage features, and temporal variation. Spatial patterns of species distributions indicated significant upstream effects of impoundment, fragmentation being the single largest predictor of species distributions. Mean fluvial specialist richness was significantly greater in unfragmented (6 species/reach) than in fragmented streams (3 species/reach), whereas mean fluvial generalist richness was significantly greater in fragmented (12 species/reach) than unfragmented streams (8 species/reach). A shift in piscivore abundance and composition was also observed, with smallmouth bass Micropterus dolomieu and redfin pickerel Esox americanus replaced by largemouth bass M. salmoides and white bass Morone chrysops in the streams fragmented by impoundments. Additionally, greater total richness and piscivore abundance was observed in tributaries upstream of impoundments. Unfragmented streams showed a significantly lower total abundance of piscivores (7 fish/reach) than upstream tributaries of impoundments (14 fish/reach). The downstream presence of an impoundment led to significant homogenization of fish assemblages through a significant increase in generalist richness and abundance in fragmented streams and a shift in the abundance and type of piscivores.

Historical Changes in Fish Assemblage Structure in Midwestern Nonwadeable Rivers

“…Moreover, sedimentation has been attributed to the reduction in trophic diversity in fish assemblages in Midwestern lotic systems (Berkman and Rabeni, 1987). The findings of our study agree with Berkman and Rabeni (1987) and others (e.g., Karr et al, 1985;Guenther and Spacie, 2006;Palić et al, 2007;Gido et al, 2010) where specialized invertivorous and herbivorous fishes declined in altered fluvial environments and were replaced by habitat generalists with piscivorous, planktivorous, or omnivorous feeding strategies (e.g., habitat generalist and facultative reservoir species; Karr et al, 1985;Falke and Gido, 2006). Although our results indicate that certain groups of species have expanded, possible temporal increases in gear efficiency have occurred and influenced our results.…”

“…The reduction of flowing water and the accumulation of fine sediments potentially explain the decline of fluvial fishes with lithophilic spawning strategies. Similarly, Guenther and Spacie (2006) observed declines of lithophilic spawners due to sedimentation upstream of impoundments in the Wabash River. Increased sedimentation considerably alters the trophic structure of local fish assemblages in many Midwestern lotic systems with hydrologic disturbance (Menzel, 1981(Menzel, , 1983Poff and Allan, 1995).…”

Interannual variations of the fish assemblage in the transitional zone of the Three Gorges Reservoir: persistence and stability

“…Considerable attention has been given to the impacts on fish assemblages of downstream reaches (De Jalon et al 1994;Quinn and Kwak 2003;Merona et al 2005) and upstream reaches (Gido et al 2000;Quist et al 2005;Guenther and Spacie 2006). Remarkable changes in fish assemblages have been found after the impoundment of reservoirs.…”

Diet of Grass Pickerel (Esox americanus vermiculafus) in Indiana Streams

“…We found that the grass pickerel was a top carnivore (piscivore) within these Indiana ecosystems, which is similar to Guenther and Spacie (2006). Top carnivore presence in an ecosystem is an important factor in evaluating fish communities and can be used in fisheries management to evaluate the overall health of the ecosystem.…”

“…As the quality of a stream declines, top carnivore populations decline and disappear (Karr 1981). For example, Guenther and Spacie (2006) found increased redfin pickerel (= grass pickerel) in streams that were not associated with downstream reservoirs. The northern pike is thought to structure fish communities primarily through predation (Paukert and Willis 2003), and this scenario could be applied to the grass pickerel in Indiana.…”