Occurrence, abundance and associations of Topeka shiners (Notropis topeka) in restored and unrestored oxbows in Iowa and Minnesota, USA

Abstract

In the USA, the Topeka shiner (Notropis topeka) is a federally listed endangered species that has been in decline for decades. A key reason for the decline is the alteration of naturally flowing streams and associated oxbow habitats resulting from land‐use changes. The focus of recent conservation efforts for Topeka shiners has been the restoration of oxbow habitats by removing sediment from natural oxbows until a groundwater connection is re‐established. This restoration practice has become common in portions of Iowa and south‐west Minnesota. The goals of this study were to compare the occurrence and abundance of Topeka shiners in restored and unrestored oxbows and to determine the characteristics that influenced their presence in these systems. In 2016–2017, 34 unrestored and 64 restored oxbows in the Boone, Beaver Creek, North Raccoon and Rock River basins in Iowa and Minnesota were sampled for their fish assemblages and abiotic features. Topeka shiners were present more often and with higher average relative abundances in restored oxbows. Nonmetric multidimensional scaling ordinations indicated that fish assemblages found in oxbows where Topeka shiners were present were less variable than assemblages found at oxbows where they were absent, but that abiotic characteristics were similar between oxbow types. Logistic regression models suggested that the presence of Topeka shiners in oxbows was positively associated with species richness, brassy minnow (Hybognathus hankinsoni) catch per unit effort (no. fish/100 m2; CPUE), orangespotted sunfish (Lepomis humilis) CPUE, dissolved oxygen and turbidity, and negatively associated with oxbow wetted length. These results highlight the use of restored oxbows by Topeka shiners while also providing new information to help guide restoration and conservation efforts.

Multipurpose Oxbows as a Nitrate Export Reduction Practice in the Agricultural Midwest

“…In the agricultural Midwest, oxbows are important habitats for endangered Topeka shiners and other fish SGCN (Bakevich et al, 2013; Simpson et al, 2019), as well as waterfowl (LaGrange and Dinsmore, 1989). A recent study of 98 oxbows and 111 nearby streams in the current Topeka shiner range in Iowa and Minnesota reported 49 fish species in oxbows and 58 fish species in streams (Simpson, 2018).…”

“…Five species were found in oxbows but were not found in streams. Of the 64 restored and 34 unrestored oxbows sampled, restored oxbows harbored populations of Topeka shiners more frequently than unrestored oxbows, and populations in the restored oxbows tended to be more abundant (Simpson et al, 2019). Coincident with the period of accelerating oxbow restoration, the distributional status of Topeka shiners in Iowa has recently reversed a previously declining trend, suggesting that oxbow restoration is contributing to the species' improving status (Pierce et al, 2019).…”

“…Oxbows are key components of floodplain habitat diversity (Ward, 1998; Amoros and Bornette, 2002; Tockner and Stanford, 2002) and are important habitats for many species in the agricultural Midwest, including several fish Species of Greatest Conservation Need (SGCN; Iowa Department of Natural Resources, 2015) such as the federally endangered Topeka shiner ( Notropis topeka ) (Bakevich et al, 2013; Simpson et al, 2019). To date, oxbow restoration in midwestern agricultural areas has primarily focused on creating habitat for the Topeka shiner.…”

Factors associated with distributions of six fishes of greatest conservation need in streams in midwestern USA

“…Oxbows are disconnected slack‐water areas in stream floodplains that have been identified as critical habitats for Topeka shiners (Kenney, 2013; Utrup, 2015; Simpson et al, 2019). Topeka shiners were recently captured at 41% of oxbows sampled in these basins (Simpson et al, 2019). By comparison, Topeka shiners were present at 36% of stream sites in the present study.…”

“…A key factor contributing to its decline is habitat loss caused by stream channelization (Wall et al, 2004; Panella, 2012). Topeka shiner has been associated with oxbows in Iowa containing submerged vegetation and often co‐occurs with fathead minnows ( Pimephales promelas ) and orangespotted sunfish ( Lepomis humilis ; Bakevich, Pierce & Quist, 2013; Bakevich, Pierce & Quist, 2015; Campbell et al, 2016; Simpson et al, 2019). Instream restoration efforts have focused on removing structures that block fish movement (e.g.…”