Geology topics

Maeghen Wedgeworth

Publications and source records attributed to Maeghen Wedgeworth.

4 recordsLinked to original sources

USGS2023

Conservation at the nexus of niches: Multidimensional niche modeling to improve management of Prairie Chub

Objective A central challenge in applied ecology is understanding how organisms are spatially and temporally distributed and how management might be tailored to maintain or restore species distributions. The niche concept is central to understanding species distributions, but the diversity of niche definitions requires that multiple dimensions be considered. For example, the Grinnellian niche concept focuses on environmental conditions that allow species to persist, the Eltonian niche concept stresses the influence of biotic interactions, and the fundamental niche concept considers both abiotic and biotic environmental features to define spaces that organisms could occupy. Methods We combined abiotic ( A ), biotic ( B ), and movement ( M ) information (collectively, BAM model) to map the multidimensional niche of Prairie Chub Macrhybopsis australis , a regionally endemic freshwater fish currently under review for listing under the Endangered Species Act. We estimated A using remotely sensed environmental riverscape variables, B using the spatial distribution of a hybridization zone between Prairie Chub and Shoal Chub M. hyostoma , and M using data from a mark–recapture study. Result The BAM model estimated the spatial extent of multiple niches, including the Grinnellian ( A ; extent = 944 km of river), Eltonian ( B ; 2974 km), and fundamental niche (overlap of A + B ; 645 km) niches. When A , B , and M components were combined, the estimated extent of the Prairie Chub niche was 645 km. Conclusion Our work shows that the realized, multidimensional niche of Prairie Chub includes medium to large rivers with high habitat connectivity in the upper–middle Red River basin upstream of the distribution of Shoal Chub. The current Prairie Chub distribution could be maintained by preventing further habitat fragmentation and maintaining the environmental gradient separating Prairie Chub from Shoal Chub. Expansion of the species distribution may be possible through restoration of longitudinal fluvial connectivity.

North American Journal of Fisheries Management↗

USGS2023

A hierarchical approach to fish conservation in semiarid landscapes: A need to understand multiscale environmental relationships

A multiscale perspective is essential for conservation planning of riverine fishes. Coarse-scale habitat (e.g., basis) can influence both finer-scale habitat characteristics (e.g., reaches and microhabitat) and associated species distributions. Finer-scale management and habitat rehabilitation efforts can fail without the consideration of coarser-scale constraints. We provide a conceptual hierarchical framework for multiscale fish conservation strategies in the semiarid Great Plains. The Great Plains stream network is highly fragmented due to dam construction, water withdrawals, and increased drought severity. Our framework uses relationships with basin-scale connectivity and streamflow and reach-scale physicochemical characteristics in the context of aiding species reintroduction and stream habitat improvements.

Book chapter↗

USGS2022

Variation in Prairie Chub hatch relationships across wet and dry years in the upper Red River basin

Objective The Prairie Chub Macrhybopsis australis is a poorly studied minnow species endemic to the upper Red River basin and is of both state and federal conservation interest due to uncertainty about its life history and potential listing status. The upper Red River basin of Oklahoma and Texas is a harsh environment where drought and extreme flow events are exacerbated by human alterations. As an assumed pelagic-broadcast-spawning minnow, the Prairie Chub is capable of a protracted spawning season and larval fish survival is assumed to be linked to discharge and streamflow variability. Methods We systematically collected 2,017 age-0 Prairie Chub from seven sites (North Fork Red River, Salt Fork Red River, Pease River, Red River, Prairie Dog Town Fork Red River, North Wichita River, and South Wichita River) with variable flow patterns during April–September 2019 and May–August 2020. We used otolith age estimates and back calculations to determine successful spawning dates. We used a hurdle model framework to examine relationships between hatch probability and hatch frequency. Result Hatch probability had a negative relationship with calendar day and declined as calendar day increased. Hatch counts peaked in late June and early July and declined thereafter in 2019 but showed no discernible peak during the spawning season in 2020. Hatch probability during the spawning season increased with relative flow and air temperature. Increased hatch counts were also positively related to discharge variability (CV) for the 10 d prior to hatch dates. Conclusion Our findings indicated that successful hatches had considerable spatial and temporal variability, with some sites contributing minimally to the population during some years. Spatial and temporal variability of hatch probability and hatch frequencies pose a variety of considerations for future conservation and management efforts, particularly given the pending federal listing status of the species.

North American Journal of Fisheries Management↗

USGS2021

Movement, recruitment, and abundance relationships of Prairie Chub: An endemic Great Plains cyprinid

The Prairie Chub Macrhybopsis australis is a poorly studied endemic cyprinid of the upper Red River basin and is listed as threatened in Texas and of greatest conservation need in Oklahoma. Hypothesized mechanisms have been proposed to explain the decline of pelagic broadcast spawning minnows including disrupted spawning cues, reduced recruitment, degraded habitat complexity, and reduced water availability and connectivity. Our study objectives were to evaluate Prairie Chub movement, identify spawn timing, and estimate abundance of Prairie Chub at locations in the upper Red River basin. We assessed Prairie Chub movement using a mark-recapture experiment with multiple tag and recapture occasions during late spring through summer (i.e., May-August) of 2019 and 2020. We tagged 5,771 Prairie Chub during summers of 2019 and 2020 and recaptured 213 fish across both summers. We conducted recapture events at approximately 2-week intervals from late May to August of 2019 and 2020. Movement by Prairie Chub was consistently greater than expected under the restricted movement paradigm. The average expected movement distance of the stationary population component was 2 m in 2019 and 3 m in 2020, whereas the expected average movement distance for the mobile population component was 42 m in 2019 and 75 m in 2020. We found no evidence of upstream bias in adult Prairie Chub movement during our study. We processed otoliths for 2,017 age-0 Prairie Chub across 7 rivers and two spawning seasons (i.e., 2019 and 2020). The likelihood of spawning and frequency of observed hatches per spawning date were higher in 2019 compared to 2020. The probability of spawning increased with increasing scaled discharge and average temperature in both 2019 and 2020. Spawning was more likely to occur earlier in the sample season though substantial spatial and temporal variation in spawning success was evident among rivers. The number of successful hatches observed per spawning day was highest in the Pease and Red rivers and lowest in the Salt Fork and South Wichita rivers for both years. We conducted 104 abundance surveys in 2019 and 2020. Our abundance estimates were consistently lower in upstream reaches, higher in downstream reaches, and more variable in mid reaches. We found Prairie Chub abundance was related to several covariates, but abundance did not vary much between years. Overall, adult Prairie Chub abundance was higher in the eastern portion of their range and increased with increasing discharge and turbidity but decreased at higher water temperatures. Adult Prairie Chub abundance had a quadratic relationship with salinity where Prairie Chub density peaked at a salinity of 10 ppt and then declined by nearly 100% when salinities reached 20 ppt. Our juvenile Prairie Chub abundance model had similar but weaker relationships with covariates compared to the adults; however, juvenile abundance was higher in 2020 compared to 2019. Our results indicate conservation of Prairie Chub and ecologically similar species would benefit from maintaining broadly connected habitats (i.e., for movement and drift). We show substantial variation in spawning patterns among rivers that has important implications for developing conservation actions. If agencies are concerned about abundance of Prairie Chub, then management agencies may want to consider the strong relationship with salinity when desalinization projects are proposed. Considering how salinity may narrow the realized niche of Prairie Chub, agencies interested in Prairie Chub persistence may want to prevent large changes in salinity concentrations in the species’ remaining habitat.

Report↗