Relationship among Fish Assemblages and Main‐Channel‐Border Physical Habitats in the Unimpounded Upper Mississippi River

Abstract

Large rivers worldwide have been altered by the construction and maintenance of navigation channels, which include extensive bank revetments, wing dikes, and levees. Using 7 years of Long‐Term Resource Monitoring Program (LTRMP) data collected from the unimpounded upper Mississippi River, we investigated assemblages in two main‐channel‐border physical habitats—those with wing dikes and those without wing dikes. Fishes were captured using daytime electrofishing, mini‐fyke netting, large hoop netting, and small hoop netting. Our objectives were to (1) assess associations among fish species richness, physical measurements, and main‐channel‐border physical habitats using stepwise multiple regression and indicator variables; (2) identify abundant adult and young‐of‐year (age‐0) families in both physical habitats to further investigate assemblage composition; and (3) calculate standardized species richness estimates within each physical habitat for adult and age‐0 fishes to provide additional information on community structure. We found species richness was greater at wing dikes for both adult and age‐0 fishes when compared with main channel borders. Stepwise multiple regression revealed significant relationships between adult species richness and passive gear deployment (e.g., hoop nets and mini‐fyke nets), physical habitat type, and river elevation, as well as interactions between physical habitat and passive gears, and physical habitat and transparency (i.e., Secchi depth). This model explained 56% of the variance in adult species richness. Approximately 15% of the variation in age‐0 species richness was explained by the sample period, sample date, transparency, physical habitat, and depth of gear deployment. Long‐term impacts of river modifications on fishes have not been well documented in many large river systems and warrant further study. The findings from this study provide baseline ecological information on fish assemblages using main channel borders in the unimpounded upper Mississippi River, information that will aid managers making channel maintenance decisions in large river systems.

Patterns in fish species composition and assemblage structure in the upper Salado River lakes, Pampa Plain, Argentina

“…The assemblage of species that make up fish communities within a river/stream network is attributed mostly to how individual species distributions respond to patterns in vegetated patches (Araujo-Lima et al, 1986;Growns et al, 2003;Pelicice et al, 2008), hydrological connectivity (Amoros & Bornette, 2002;Petry et al, 2003), water transparency (Rodríguez & Lewis, 1997;Reyjol et al, 2008;Melo et al, 2009), physicochemical variables (Koné et al, 2003;Barko et al, 2004), food resources availability (Grenouillet & Pont, 2001), and prey-predator interactions (Piana et al, 2006) among others.…”

Effects of conservation wetlands on stream habitat, water quality and fish communities in agricultural watersheds of the lower Mississippi River Basin

“…Similarly, fish community metrics did not suggest significantly "improved" or "healthier" fish communities in streams with wetland-dominated watersheds, as might be expected. Although fish community metrics tended to be greater in most wetland streams (e.g., Gregory et al, 1991;Heatherly and Whiles, 2007), metric values were highly variable both spatially and temporally; thus, between-stream type differences were not detecTable Several studies (e.g., Karr et al, 1985;Lisle and Hilton, 1992;Barko et al, 2004) have associated improved or otherwise healthier fish communities with factors such as low sediment deposition and low degrees of channel alteration, which are factors more associated with wetland streams in this study. In addition, other studies (e.g., Walser and Bart, 1999;Heitke et al, 2006) have observed greater fish species diversity and richness in streams with forested watersheds compared to streams with agricultural watersheds.…”

A Comparison of Fish Catch Rate with Two Different Benthic Trawls in the Missouri River

“…Fish assemblages were compared between both gears with the groupings either being completely separated (R > 0.75), overlapping but noticeably different (R -0.5), or barely separable (R < 0.25) (Clarke andWanvick 2001, Utrup andFisher 2006). Because sample size varied between gears, we used rarefaction to compare species richness between OTOl and OT16 (Simberloff 1972, Barko et al 2004, software by Holland 2003. Samples were standardized to correct for differences in effort allocation between trawl types.…”

“…Samples were standardized to correct for differences in effort allocation between trawl types. We randomized samples (without replacement) and resampled to the smallest sample size (OT01; N = 661) (Barko et al 2004). Rarefaction is a statistical tool used to calculate expected number of species at a site when a given number of fish are collected (Sanders 1968, Hurlbet 1971, Simberloff 1972).…”