Floods, drying, habitat connectivity, and fish occupancy dynamics in restored and unrestored oxbows of West Central Iowa, USA

Abstract

1. In the agricultural landscape of the Midwestern USA, waterways are highly altered.Oxbows are among the few remaining off-channel habitats associated with streams, supporting fish assemblages that include the endangered Topeka shiners Notropis topeka in portions of their remaining range. Oxbow restorations seek to increase the number and quality of oxbows for Topeka shiners. For oxbows to provide optimal habitat, periods of isolation from streams and connection with streams during floods are necessary. Water levels and patterns of drying and hydrological connectivity between 12oxbows and their neighboring streams in West Central Iowa were continuously monitored from May to October 2011, and fish assemblages were assessed for responses to the differing hydrodynamics using dynamic occupancy modelling.3. The 12 oxbows exhibited varied hydrodynamics and connectivity with streams.Two oxbows never contained fish; these oxbows never flooded and were among the three oxbows that were dry for the longest periods. 4. Occupancy modelling suggested that connection with the stream via floods significantly increased the probability of colonization, and low water level increased the probability of local extinction from oxbows. Thirteen of the 16 fish species encountered had detection probabilities over 60%, and eight had detection probabilities over 90%, including Topeka shiners. 5. None of the five previously restored oxbows flooded; all five contained fish, but only one contained Topeka shiners. Three of the four oxbows containing Topeka shiners flooded and all four dried at least once.6. These results suggest that planning for future oxbow restorations should consider:(i) sites that flood frequently; and (ii) construction methods promoting alternating periods of isolation from and connection with streams.

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

“…Green sunfish have also been reported as a potential nest associate of Topeka shiner, but green sunfish CPUE was not significantly associated with Topeka shiner presence in this study. Topeka shiner associations with brassy minnow have been observed less frequently, although an association was noted by Fischer et al (2018). Both species are associated with instream habitat dominated by slow current and vegetated backwaters (Carl, Clemens, & Lindsey, 1967;Nelson & Paetz, 1992;Page & Burr, 2011;Pflieger, 1997).…”

“…Oxbows are typically disconnected from the stream except during periods of flooding, when fishes can enter from and exit to adjacent streams. Over time, silt deposits from repeated flooding can reduce oxbow water depths (Ishii & Hori, 2016), increasing susceptibility to summer hypoxia and drying while also being prone to completely freezing in the winter (Escaravage, 1990), which can result in the elimination of fishes (Fischer, Bakevich, Shea, Pierce, & Quist, 2018;Townsend, Boland, & Wrigley, 1992). To prevent fish kills, state, federal and non-profit agencies in Iowa and Minnesota are restoring oxbows to a deeper, more original FIGURE 1 Aerial photos depicting natural oxbow formation over time, White Fox Creek, Woolstock, IA, USA.…”

Lateral hydrological connectivity differentially affects the community characteristics of multiple groups of aquatic invertebrates in tropical wetland pans in South Africa

“…Earlier studies indicate that biodiversity in floodplains depends on the connection to the river, with relatively lower diversity at low LHC due to limited input of nutrients from the river and the lower dispersal probability (Thomaz, Bini, & Bozelli, 2007;Ward, Tockner, & Schiemer, 1999). nutrients) and homogenising effects through an influx of propagules (Conceição, Higuti, Campos, & Martens, 2018;Fischer, Bakevich, Shea, Pierce, & Quist, 2018;Ward et al, 1999). nutrients) and homogenising effects through an influx of propagules (Conceição, Higuti, Campos, & Martens, 2018;Fischer, Bakevich, Shea, Pierce, & Quist, 2018;Ward et al, 1999).…”

“…Similarly, regular flooding promotes high LHC, leading to lower biological diversity due to dilution of floodplain conditions (e.g. nutrients) and homogenising effects through an influx of propagules (Conceição, Higuti, Campos, & Martens, 2018;Fischer, Bakevich, Shea, Pierce, & Quist, 2018;Ward et al, 1999). The highest levels of diversity in river floodplain systems are often observed at intermediate levels of LHC (Gallardo et al, 2014;Turić et al, 2015;Ward & Tockner, 2001).…”

Status of the Topeka Shiner in Iowa

“…The Topeka shiner Notropis topeka is native to Iowa, Kansas, Minnesota, Missouri, Nebraska, and South Dakota (Lee et al, 1980) and has been federally listed as endangered for two decades (Tabor, 1998). Since being listed interest in Topeka shiners has resulted in numerous studies of their physiology (Adams et al, 2000;Koehle and Adelman, 2007), ecology and natural history (Kerns and Bonneau, 2002;Mammoliti, 2002;Stark et al, 2002;Witte et al, 2009;Campbell et al, 2016;Mosey, 2017), genetics (Bergstrom et al, 1999;Michaels, 2000;Anderson and Sarver, 2008), habitat relationships (Schrank et al, 2001;Wall et al, 2004;Gerken and Paukert, 2013;Bakevich et al, 2013;Fischer et al, 2018), and distributional status (Dahle, 2001;Blausey, 2001;Pasbrig and Lucchesi, 2012;Nagle and Larson, 2014;Bakevich et al, 2015). A recent synthesis of published research and unpublished distributional data for the purposes of characterizing the Topeka shiner's range-wide biological status, referred to as a ''species status assessment'' or ''SSA'' (U.S. Fish and Wildlife Service, 2018a), was used to inform a Recovery Plan (U.S. Fish and Wildlife Service, 2018b), and proposes four future scenarios, ranging from continued decline to significant conservation gains, depending on the intensity and geographic extent of conservation actions taken.…”