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Water quality standards based on sub-lethal effects and performance optima for aquatic organisms, rather than onset of mortality, are more ecologically relevant for management of species of conservation concern. We investigated the effects of hypoxia, temperature (with acclimation), nitrogenous chemical compounds, and chloride on Topeka shiners (Notropis topeka) by monitoring behavioral responses to a reduction in oxygen and, using swimming speed, determining thermal optima and onset of effect for concentrations of nitrogenous compounds and chloride. We found ASR50 (i.e., dissolved oxygen concentrations where 50% of fish use aquatic surface respiration) to be 1.65 mg/L and ASR90 to be 1.08 mg/L of dissolved oxygen. Optimum temperatures for the species ranged from 17.7 to 28.0 °C, while predicted 100% mortality ranged from 33.7 to 40.3 °C, depending on the temperature at which fish were acclimated prior to experiments. Ammonia and sodium chloride reduced swimming speed at concentrations below known LC50 values, while nitrite concentrations did not correspond with swimming speed, but rather, post-experiment mortality. This provides insight into where Topeka shiners can not only persist, but also thrive. Although swimming speed may not be a suitable metric for determining the effects of all contaminants, our focus on optima and sub-lethal effects over tolerance allows selections of the most suitable reintroduction site matching the species' physiological profile. [ABSTRACT FROM AUTHOR]

Many fish species of greatest conservation need (SGCN) in Iowa and Minnesota, USA, have been in decline for decades. A key reason for the decline is the alteration and degradation of naturally flowing streams owing to land use changes resulting from agricultural practices. Populations of several fishes have been adversely affected by widespread stream channelization that has resulted in more homogeneous stream habitats throughout Iowa and Minnesota.The goal of this study was to determine the abiotic and fish assemblage characteristics associated with the presence of these rare fishes. Electrofishing and seining were used to sample fish assemblages and 43 abiotic characteristics were measured at 111 sites in the North Raccoon and Boone River basins in central Iowa and the Rock River and Beaver Creek basins in north‐west Iowa and south‐west Minnesota during 2016 and 2017.Six SGCN, including the federally endangered Topeka shiner (Notropis topeka), were included in statistical modelling to determine habitat and fish assemblage characteristics associated with their presence.Species‐specific nonmetric multidimensional scaling ordinations indicated that abiotic characteristics and fish assemblages often differed between sites where SGCN were present and absent. Random forest and logistic regression models suggested that the presence of four of six SGCN were positively associated with species richness, whereas all other 10 important abiotic and fish assemblage variables were unique to only one or two of the six SGCN.Topeka shiners were present at 36% of sites and were positively associated with orangespotted sunfish (Lepomis humilis) catch per unit effort while being negatively associated with canopy cover and fantail darter (Etheostoma flabellare) catch per unit effort. [ABSTRACT FROM AUTHOR]

A hybrid model was used to characterize potential ecological risks posed by atrazine to the endangered Topeka shiner. The model linked a Topeka shiner individual‐based bioenergetics population model (TS‐IBM) to a comprehensive aquatic system model (CASMTS) to simulate Topeka shiner population and food web dynamics for an Iowa (USA) headwater pool. Risks were estimated for monitored concentrations in Iowa, Missouri, and Nebraska (USA), and for monitored concentrations multiplied by 2, 4, and 5. Constant daily atrazine concentrations of 10, 50, 100, and 250 µg/L were assessed. Exposure–response functions were developed from published atrazine toxicity data (median effect concentrations [EC50s] and no‐observed‐effect concentrations). Two toxicity scenarios were developed: the first included sensitive and insensitive species of algae, and the second reduced algal EC50 values to increase atrazine sensitivity. Direct and indirect effects of atrazine on Topeka shiner prey were modeled; direct effects on Topeka shiner were not assessed. Risks were characterized as differences between population biomass values of 365‐d baseline and exposure simulations. The results indicated no discernable food web effects for monitored atrazine concentrations or constant exposures of 10 µg/L on Topeka shiner populations for either toxicity scenario. Magnified monitored concentrations and higher constant concentrations produced greater modeled indirect effects on Topeka shiners. The hybrid model transparently combines species‐specific and surrogate species data to estimate food web responses to environmental stressors. The model is readily updated by new data and is adaptable to other species and ecosystems. Environ Toxicol Chem 2019;38:2243–2258. © 2019 SETAC. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

• Endangered fish populations may experience stressors mediated via the food web. • A hybrid model for Topeka shiner (Notropis topeka) populations was developed. • Comparison between stand-alone food-web model (CASM) and hybrid model was conducted. • Impacts of hypothetical changes in food availability on populations were assessed. • Hybrid model provides assessment tool for direct and food-web mediated impacts. The Topeka shiner, a small cyprinid fish, is a seminal example of an endangered aquatic species in the Midwestern USA. Populations and their associated critical habitats may experience potential direct and/or indirect effects from anthropogenic activity. However, potential impacts on fish populations from alterations in the food web are difficult to predict because they are based on complex dynamics of food web interactions. In order to simulate Topeka shiner population dynamics under different food-web scenarios, a hybrid modeling approach was developed by linking an aquatic food web model (comprehensive aquatic systems model, CASM TS) with a species-specific, individual-based population model (TS-IBM). The CASM TS was parameterized and calibrated to represent the waterbody conditions and aquatic species community in a small headwater pool in Iowa, representative of key habitat for the Topeka shiner within its geographical range. In the TS-IBM, life history, growth, and diet are represented and based on data available from the literature for the Topeka shiner and/or surrogate species. The two models are linked by the transfer of daily biomasses of Topeka shiner diet items. We simulated the effects of alterations of the food web on the Topeka shiner populations by systematically reducing the available prey base biomass. Reductions in different food groups had varying impacts on the simulated Topeka shiner populations and were dependent on the species' preference for detritus consumption. Simulations also included predation and identified predator densities to which Topeka shiner populations were vulnerable. The hybrid model provides a platform for the assessment of potential direct and food-web mediated indirect effects of stressors for the purposes of risk assessment, habitat management, and species recovery plans. [ABSTRACT FROM AUTHOR]

Abstract: 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 12 oxbows 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. 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. 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. 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. 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. [ABSTRACT FROM AUTHOR]

The Topeka shiner Notropis topeka is a federally endangered fish species that is estimated to occupy only 20% of its historic range. In Iowa Topeka shiners have been in decline for decades. Our goal was to determine the present distribution of Topeka shiners in the west-central portion of their range in Iowa and to characterize the extent of its decline. We compared the current distribution to distributions generated from earlier collections. We found Topeka shiners in six of 22 watersheds where they occurred historically. Status of Topeka shiners was judged to be stable in 27% of the watersheds, at risk in 45% of the watersheds, and possibly extirpated in 27% of the watersheds. None were classified as increasing. Based on comparison of the historical distribution with more recent ones, Topeka shiners in west-central Iowa showed a 27% decline a decade ago and currently exhibits a 73% decline in their distribution. The collective evidence from four of five other states in the species' range reveals similar declines. This study provides further information on the local distribution and extent of decline for this federally endangered species with a greatly reduced and fragmented overall distribution. [ABSTRACT FROM AUTHOR]

Modification of the asphalt mixture is one approach used to achieve good mixtures. Fibers and polymers are generally two important modifiers in improving pavement performance, though fibers have received much attention for their enhancement effects among other modifiers for asphalt. In this research by evaluating various methods of Polypropylene fibers mixing in asphalt mixture and choosing the most suitable one, adding 0.1 to 0.5 of Polypropylene fibers contents in asphalt mixtures based on Topeka aggregation are studied. The results indicated that polypropylene has direct ratio to increasing of Marshall Stability, VTM and VMA and has reverse ratio to decreasing of Flow, VFA and Unit Weight. These results are because of fiber's resistive properties, absorption by bitumen and aggregates and also chemical reactions in the mixture. This modifier causes improvement in asphalt physical and mechanical properties based on Topeka aggregation. By considering polypropylene's applications, usage of it in highways with heavy traffic can be discussed in order to increasing pavement life. [ABSTRACT FROM AUTHOR]

Topeka shiners (Notropis topeka) were historically abundant throughout many Great Plains streams but their abundance and distribution declined and the species was listed as federally endangered in 1999. However, few studies have examined how Topeka shiner populations are linked to biotic and abiotic factors. Thus, the objectives of this study were to identify trends in Topeka shiner distribution from 1995 to 2008 and determine which fish assemblage and habitat factors were most associated with Topeka shiner distribution in Kansas streams. Fish and in-stream habitat metrics were collected from 34 sites in northeast Kansas in 1995, 2003, and 2008. Stepwise discriminant function analyses (DFA) were used to determine if fish assemblage percent composition and in-stream and landscape habitat factors could be used to differentiate among years and between sites with and without Topeka shiners. Higher percent composition of rosyface shiner (Notropis rubellus) was generally indicative of sites with Topeka shiners whereas higher relative abundance of central stoneroller (Campostoma anomalum) and largemouth bass (Micropterus salmoides) were associated with sites without Topeka shiners. Sites with Topeka shiners also tended to have more gravel substrate and greater mean stream length, whereas sites without Topeka shiners generally had higher proportional impoundment area and proportional urban land area. These findings suggest that anthropogenic alteration of habitat in and around streams with Topeka shiners may facilitate their declines and establishment of non-native or generalist fishes. Our results may help managers identify habitats with the greatest need for protection or restoration and may help protect Topeka shiner populations from further population declines. [ABSTRACT FROM PUBLISHER]

Our goal was to identify habitat, fish species, and fish assemblages associated with the occurrence of Topeka ShinersNotropis topekain stream and off-channel habitat (OCH) of west-central Iowa. Fish assemblages and habitat characteristics were estimated in 67 stream and 27 OCH sites during 2010–2011. Topeka Shiners were sampled in 52% of OCH sites, but in only 9% of stream sites, which supports the hypothesis that OCH is an important component of their life history. Fish assemblages containing Topeka Shiners were different from those that did not contain Topeka Shiners in OCH sites, but this was not evident in stream sites. Results from logistic regression models suggested that Topeka Shiner presence was associated with increased submerged vegetation and abundance of Fathead MinnowPimephales promelas. Contrary to the findings of other studies, the abundance of large piscivorous fishes was not associated with the occurrence of Topeka Shiners. Our results provide new information about the biology and life history of the Topeka Shiner that will guide habitat restoration and other recovery efforts. Received July 17, 2012; accepted August 20, 2013 [ABSTRACT FROM AUTHOR]

Fish use of dugouts (livestock watering holes) in stream floodplains was evaluated for the first time in this study. Twenty-two fish species were found in 13 of 20 dugouts near a stream, while 20 species were captured from the adjacent stream reach. Relative species composition in stream and dugouts was similar but fish were more abundant in dugouts. Both assemblages were dominated by fathead minnow (Pimephales promelas), black bullhead (Ameiurus melas), orangespotted sunfish (Lepomis humilis), green sunfish (L. cyanellus), and brook stickleback (Culaea inconstans) in decreasing order of magnitude. The endangered Topeka shiner (Notropis topeka) was found in seven dugouts. The presence of several length groups of Topeka shiners indicated reproduction in two dugouts that were close to the stream (<15.2 m) but remained disconnected from the stream throughout the study. Our results suggest that dugouts separate from the stream within frequently inundated zones can provide off-channel habitat for fishes. [ABSTRACT FROM AUTHOR]

We have developed a set of eight polymorphic microsatellite markers for the endangered Topeka shiner, Notropis topeka. Allelic diversity at each of these loci was assessed in a single isolated population from eastern South Dakota, USA. The allelic diversity ranged from four to 15 alleles. These are the first microsatellite markers to be reported for this species. These markers are being used in a more thorough study of the population structure throughout the remaining range of this species. [ABSTRACT FROM AUTHOR]