Banner photo: Confluence of the Grand and Thompson rivers, northern Missouri
Overview
I have led several research projects (listed below) meant to help agencies understand and manage freshwater and diadromous species. Generally, my research has fallen under four themes:
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Framework for limiting movements of invasive fishes into recreationally important oxbow lakes & tributaries
Bighead and Silver carps (bigheaded carps) are invasive species that jeopardize native fishes, and commercial and recreational fisheries. These invasive species require long stretches of unimpounded flowing river to successfully reproduce. Consequentially, water-control structures (semi-permeable barriers) on lentic waterbodies, such as oxbows, are potential opportunities for limiting spread of bigheaded carps. Our goal is to examine whether operations of water-control structures limit movements of bigheaded carps. We will track movements of Silver Carp between Yazoo River and Eagle Lake oxbow through two seasonally opened water-control structures using active and passive acoustic telemetry. Project results will reveal the timing and extent of Silver Carp movements, thereby informing how operations of the numerous water-control structures throughout the lower Mississippi River Alluvial Valley might be used as tools to limit invasive species. Collaborators: Mississippi Department of Wildlife, Fisheries, & Parks; U.S. Fish & Wildlife Service; U.S. Geological Survey |
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Influence of road culvert design and groundwater hydrology on headwater crayfish & fish assemblages
Natural resource managers increasingly recognize that poor-fitting road culverts can block movements of fishes. However, very little is known whether culverts potentially limit movements of crayfishes, especially those inhabiting ephemeral headwater streams. For example, the combination of stream drying and impassable culverts could lead to extirpations of crayfishes upstream of impassable culverts. Therefore, we have deployed 80 groundwater loggers to monitor stream drying upstream and downstream of 40 road culverts. Using these stream hydrology data, we will link differences between crayfish and fish assemblages on both sides of culverts to stream drying and physical characteristics of culverts that could limit passage. Partners: US Forest Service; US Fish and Wildlife Service; NC State University; MS State University; US Geological Survey |
Resolving taxonomic and distributional uncertainty of Mississippi crayfishes
Mississippi supports one of the highest concentrations of crayfish biodiversity on Earth (65 species native to MS). Four headwater or “rivulet” crayfishes found only in Mississippi were petitioned for review under the Endangered Species Act. Our goal is to support these Species’ Status Assessments by US Fish & Wildlife Service. Our objectives are to resolve taxonomic uncertainty among species using genomic and morphometric analyses, delimit species’ distributions, and assess persistence of rivulet crayfishes at historical collection localities across Mississippi. In spring of 2021, field crews are undertaking one of the largest coordinated crayfish surveys in Mississippi history. Our survey design – which pairs morphometric, genomic, and occupancy data – could provide a framework for supporting status assessments of data-deficient species with taxonomic and distributional uncertainty. Sponsors: US Fish & Wildlife Service; US Geological Survey; Mississippi Sate University; US Forest Service; University of Mississippi |
Suitability ephemeral streams & roadside ditches to support headwater crayfish assemblages
Ephemeral waterbodies (seasonally wetted streams, vernal pools, roadside ditches) comprise the vast majority of stream networks, but very few of these waterbodies are named or georeferenced. Consequentially, aquatic taxa that inhabit these aquatic habitats are likely under counted. Further, species that specialize on these waterbodies could be completely overlooked by traditional monitoring programs, which traditionally focus effort on permanent streams. Using high-resolution LiDAR elevation models, we are developing stream networks that include ephemeral waterbodies. We're conducting intensive surveys of these networks for crayfish and fish assemblages to quantify total and unique biodiversity found in these previously un-mapped aquatic habitats. Partners: US Fish & Wildlife Service; US Geological Survey; Mississippi Sate University; US Forest Service. |
Conservation stocking of Frecklebelly Madtom in tributaries of the Tennessee-Tombigbee Waterway
Conservation stocking is an increasingly used tool for restoring extirpated populations within waterbodies. Although the science of artificially propagating non-game species has grown tremendously, comparatively limited research has gone into the follow-up monitoring designs to evaluate restoration success. We are working with USFWS and MDWFP to restore an extirpated population of a small non-game catfish (Frecklebelly Madtom) into Bull Mountain Creek. Specifically, we crafted a post-restoration monitoring design that allows managers to distinguish sampling effort, emigration, and failed stocking success (mortality) of reintroduced madtoms. This allows managers to optimize their sampling effort across restored sites, and provides valuable information on when to terminate stocking efforts in cases where survival and recruitment of stocked fish is low due to insufficient environmental conditions to support potentially restored populations. |
Decision support tool for evaluating imperilment of southeastern fish species
The southeastern U.S. supports a wealth of freshwater species of fish, mussels, and crayfish. Unfortunately, hundreds of these species have declining populations, which can overwhelm the resources of agencies charged with saving these species from extinction. The main goal of this research is to help the US fish and Wildlife Service streamline and standardize their process for evaluating whether species are at risk of extinction. We are prototyping our approach with species that have been recently reviewed by the USFWS, including Carolina Madtom (right). If we're successful, our approach could provide a framework for evaluating imperilment of species throughout the Southeast. Collaborators: US Fish & Wildlife Service; US Geological Survey; Mississippi State University |
Methods to monitor American Eel distribution in Mississippi
The American Eel is a migratory species and an important indicator of downstream river connectivity. In Mississippi, the species has likely been affected by recently constructed migration barriers in gulf coastal rivers and may be further jeopardized by an emerging global market for juvenile eels. Thus, contemporary eel distributional data could serve as a baseline reference before expected intensifying commercial harvest in the Southeast. Eels are notoriously difficult to detect, and surprisingly, there have been few formal methodological comparisons to determine which gears are most effective at detecting this nocturnal fish. Our objectives are to estimate eel occupancy within the Noxubee River drainage and compare detection probabilities among alternative trap designs traditionally used by recreational and commercial fishers to capture eels. Sponsor: Undergraduate Research Scholars Program; College of Forest Resources, Mississippi State University |
Development of fish community sampling protocols for Missouri's mid-sized rivers
A part of my PhD developed fish sampling protocols for fish communities within mid-sized rivers. Riverine fish communities are a major knowledge gap in freshwater ecology because rivers are notoriously difficult to sample. After spending over 300 days sampling rivers across Missouri using six different gears, my team collected 140 of Missouri’s 220 fish species and over 100,000 fish! A major finding is sites (1–5 kilometers of river) often support 2–3 times more fish species than historically reported with traditional methods, and in some cases, we’ve caught upwards of 90 species at individual sites. We have since developed an analysis that improved efficiency by 50%, so biologists can use these protocols to monitor fish communities within realistic time-frames. Collaborators: Missouri Department of Conservation; US Geological Survey; University of Missouri |
Identifying fish diversity hotspots
Riverine fish communities change from source to mouth, but it isn’t always clear whether these changes are predictable, and whether certain sites support exceptionally high numbers of species (i.e., hotspots). To answer these questions, my team used our newly developed protocols to sample sites along the lower 250 kilometers of the Grand River (prairie region) and Meramec River (Ozark region) in Missouri. These are among the most intensive and extensive coordinated surveys of large rivers ever attempted. We detected 48 species in the Grand River and 103 species in the Meramec River, indicating most species within each system (including headwater fish) can be found in the mainstems! Sites supporting the most species within each system (hotspots), are large, near the Mississippi or Missouri rivers, and have high habitat diversity needed for both upland and lowland species. This knowledge will help Missouri prioritize management of specific river sections supporting high diversity and imperiled species. Collaborators: Missouri Department of Conservation; US Geological Survey; University of Missouri |
Capacity of large tributaries to support Mississippi and Missouri river fishes
The Missouri and Mississippi rivers (“great rivers”) are highly engineered for navigation, but their large tributaries may support fish species dependent on less-impacted river habitat. Unfortunately, there is little reliable fish distributional data to help biologists gauge the extent to which Mississippi and Missouri river fishes (great-river fishes) use tributaries. Using our newly developed sampling protocols, my team discovered a) tributaries support more great-river fish species than previously thought, b) tributaries with certain habitats support more great-river species than others, and c) connectivity of sites within tributaries also predicts great-river tributary use. These findings will help biologists identify important tributaries and assess impacts of severed connectivity among the great rivers and their tributaries by dams. Collaborators: Missouri Department of Conservation; US Geological Survey; University of Missouri |
Influence of flow and temperature on long-term population dynamics of crayfishes
Crayfish comprise a large percentage of freshwater diversity in the southeastern US, and are frequently eaten by sportfish, but relatively little is know about their ecology. I, along with my lab mates, partnered with the Missouri Department of Conservation to determine if flow disturbances (drought, flooding) and temperature impacted annual recruitment (number of offspring) over a 10-year period for three crayfish species. Although all three species are generally impacted by high-flow events in spring (during brooding), they respond surprisingly differently to other flow-related metrics and temperature. This information will help biologists anticipate potential impacts of increasingly frequent extreme-flow events on crayfish. Collaborators: Missouri Department of Conservation; US Geological Survey; University of Missouri |
Conservation of the federally endangered Candy Darter
My master’s research studied conservation issues underpinning the decline of the Candy Darter — an imperiled fish found only in headwater streams of the New and Gauley rivers in Virginia and West Virginia. I conducted multiple studies in which I 1) quantified suitable habitat to identify potential streams to restore populations, 2) developed standardized survey protocols to identify unknown populations, 3) identified landscape-sourced stressors causing distributional declines over the last century, 4) quantified the distribution and resource overlap between Candy Darters and an introduced, closely related competitor. Overall, Candy Darters are a coolwater species sensitive to warming water and high fine-sediment; cool and clear streams are increasingly rare, and remaining habitats are at risk of invasion. This research helped the US Fish and Wildlife Service evaluate the conservation status of Candy Darters, and guides ongoing research and management to save the species from extinction. Collaborators: Virginia Department of Game & Inland Fisheries; US Geological Survey; Virginia Tech |