Fish assemblages above and below three road crossing types are similar in a prairie stream

Background. The North American prairie biome is considered one of the most endangered ecoregions. Prairie fishes have been affected by many anthropogenic disturbances, including the construction of bridges and culverts as road crossings over streams. The objective of our study was to test fish assemblage characteristics upstream and downstream of single- and double-barreled culverts and compare them with assemblages at bridges within a single prairie stream watershed. Methods. Eight sites located near public or private roads were selected on the South Loup River, Nebraska, USA. Fish were sampled monthly from April through October 2013 using backpack electrofishing. Sampling occurred upstream and downstream of each road crossing structure. Fish collections from all months were combined to calculate species richness; species diversity; the relative abundance of two species of conservation concern in North American Great Plains streams (brassy minnow Hybognatus hankinsoni and plains topminnow Fundulus sciadicus ); the relative abundance of two introduced predators (largemouth bass Micropterus salmoides and northern pike Esox lucius ), and the relative abundance of both introduced predators combined. A two-way analysis of variance (ANOVA) test was used to determine whether these seven fish assemblage characteristics were different between upstream and downstream reaches, among road crossing structures, and between the interaction of these two factors followed by pairwise comparisons by either road crossing type, direction, or the interaction of both using a Tukey’s honest significant difference (HSD) test. Results. Only two fish assemblage characteristics appeared to be related to road crossing type or direction: species richness and relative abundance of brassy minnows. Species richness was significantly higher at bridges compared to single-barreled culverts. The relative abundance of brassy minnows was significantly different between bridges and both types of culverts but was not significantly different between the two culvert types. Discussion. Several reasons could explain the overall results of our study. First, road crossings on prairie streams may not have much effect on fish passage or fish habitat due to the low gradient of these streams. Secondly, because of bank stabilization, bridges could affect prairie fish communities and their habitats as severely as culverts within this watershed. Third, the fish communities upstream and downstream of all crossing types may represent fishes that are mostly tolerant of disturbances in general. Our study indicates that prairie streams and their fish communities could be at least somewhat tolerant and resilient to disturbances associated with road crossings, even though the small-bodied nature of many native species potentially pose higher risks of disconnection within the population.

Fish assemblages above and below three road crossing types are similar in a prairie stream

Background. The North American prairie biome is considered one of the most endangered ecoregions. Prairie fishes have been affected by many anthropogenic disturbances, including the construction of bridges and culverts as road crossings over streams. The objective of our study was to test fish assemblage characteristics upstream and downstream of single- and double-barreled culverts and compare them with assemblages at bridges within a single prairie stream watershed. Methods. Eight sites located near public or private roads were selected on the South Loup River, Nebraska, USA. Fish were sampled monthly from April through October 2013 using backpack electrofishing. Sampling occurred upstream and downstream of each road crossing structure. Fish collections from all months were combined to calculate species richness; species diversity; the relative abundance of two species of conservation concern in North American Great Plains streams (brassy minnow Hybognatus hankinsoni and plains topminnow Fundulus sciadicus ); the relative abundance of two introduced predators (largemouth bass Micropterus salmoides and northern pike Esox lucius ), and the relative abundance of both introduced predators combined. A two-way analysis of variance (ANOVA) test was used to determine whether these seven fish assemblage characteristics were different between upstream and downstream reaches, among road crossing structures, and between the interaction of these two factors followed by pairwise comparisons by either road crossing type, direction, or the interaction of both using a Tukey’s honest significant difference (HSD) test. Results. Only two fish assemblage characteristics appeared to be related to road crossing type or direction: species richness and relative abundance of brassy minnows. Species richness was significantly higher at bridges compared to single-barreled culverts. The relative abundance of brassy minnows was significantly different between bridges and both types of culverts but was not significantly different between the two culvert types. Discussion. Several reasons could explain the overall results of our study. First, road crossings on prairie streams may not have much effect on fish passage or fish habitat due to the low gradient of these streams. Secondly, because of bank stabilization, bridges could affect prairie fish communities and their habitats as severely as culverts within this watershed. Third, the fish communities upstream and downstream of all crossing types may represent fishes that are mostly tolerant of disturbances in general. Our study indicates that prairie streams and their fish communities could be at least somewhat tolerant and resilient to disturbances associated with road crossings, even though the small-bodied nature of many native species potentially pose higher risks of disconnection within the population.

Prairie stream ecology : temporal and spatial patterns of macroinvertebrates

Tallgrass prairie streams and their fauna are understudied, due in part to their rarity. The composition of prairie stream communities differs geographically due to regionally and locally determined environmental characteristics and varies over time due to disturbance events. This research focused on expanding the current knowledge of temporal and spatial variation in the macroinvertebrate communities of Missouri prairie streams. Intra-seasonal variation in the macroinvertebrate community of one prairie stream was correlated with changes in the stream environment and resulted in three relatively short-lived but significant community groupings. These intra-seasonal community shifts also affected functional feeding group structure and led to significant differences in biomonitoring measures over the course of weeks. For situations in which small, dynamic stream systems need to be monitored, sampling should be conducted at frequent intervals to capture changes in communities that may occur within seasons. The regional diversity and community structure of prairie headwater stream communities is in part driven by both the intermittent nature and the relative scarcity of prairie stream habitat. The macroinvertebrate communities of the headwater networks from five prairies in Missouri were unique. Differences in their taxonomic composition led to differences in biomonitoring metric values. The distinct community compositions of the headwater prairie streams studied and the high regional diversity documented are likely driven by geographic isolation rather than local environmental factors. Each of these prairie stream systems is an important contributor to species diversity at a regional level. Conservation and restoration efforts must work to preserve the biotic diversity in prairie streams to support existing macroinvertebrate communities that remain. For lotic insects to maintain stable populations across fragmented prairie patches and their intermittent streams in Missouri, dispersal must occur between patches to enable recolonization of streams after disturbance. Leptophlebia konza Burian was thought to be restricted to its type locality of Konza Prairie, Kansas; however, a population was discovered at Hi Lonesome Prairie in Missouri during an extensive search of 54 prairies. DNA sequence data from cytochrome oxidase subunit 1, CO1, show that both populations of L. konza lost genetic diversity during a recent bottleneck, either because of habitat fragmentation or competition from other species, including Leptophlebia johnsoni McDunnough. The rarity of L. konza populations across Missouri when taken into consideration with DNA sequence data suggest that L. konza populations are unstable and unable to disperse between remaining prairie patches. Water quality monitoring and research activities taking place in prairie streams must take into account spatial and temporal variation in both community structure and genetic diversity across these landscapes.

Using Species Distribution Models to Guide Field Surveys for an Apparently Rare Aquatic Beetle

Surveying for rare animals can be difficult but using models to predict suitable habitat can guide sampling efforts. We used models to predict suitable habitat for the Narrow-footed Hygrotus Diving Beetle Hygrotus diversipes (diving beetle hereafter), a dytiscid beetle that is known from 10 streams in central Wyoming. The diving beetle was a category-2 Candidate species for listing as Threatened or Endangered in the Endangered Species Act between 1989 and 1996, and was petitioned for listing in 2007, 2008, and 2013. Suitable habitat for the diving beetle was predicted using Maximum Entropy and Random Forest models in Wyoming. Both models predicted that the diving beetle was more likely to occur in intermittent streams with a gentle gradient, shallow water table, variable precipitation pattern, and high soil electrical conductivity, and in the warmest areas of Wyoming. We conducted surveys for the diving beetle at sites where the species had previously been found, and in new areas that were predicted suitable by our models to evaluate whether it is more widely distributed than indicated by previous estimates. We sampled beetles using dip nets and bottle-traps, and assessed water quality at each site. We collected the diving beetle at three sites in central Wyoming between 2010 and 2012 in small, alkaline, intermittent streams with disconnected pools. The aquatic habitat of the diving beetle is dynamic and our results suggest that annual precipitation patterns have a strong influence on the biogeography of this habitat. Our results also suggest that maintaining the hydrologic integrity of prairie streams in Wyoming is vital to the conservation of the diving beetle.