Dan Magoulick Lab

Integrating spatial data for predicting the influence of altered hydrologic and thermal conditions on fish assemblage traits and taxa across stream flow regimes

There is a crucial need to better understand and predict how species and assemblages respond to hydrological and thermal variations related to anthropogenic land use in streams with different flow regimes, to identify where nonlinear ecological and environmental thresholds are likely to occur under future conditions. This project will leverage high performance computing resources to develop empirical relationships for quantifying the cross-scale influence of hydrology, temperature and land use change on fish and macroinvertebrate assemblages and species of greatest conservation need (SGCN). The first phase of the proposed study will focus on rivers and streams in the Interior Highlands of Arkansas, Missouri, and Oklahoma. The second phase of the project will expand the analysis to include river systems in southern Alabama, southern Georgia and northern Florida.

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Examining effects of invasive crayfish and drought on Faxonius marchandi, an Ozark-endemic petitioned crayfish

​Faxonius marchandi (Mammoth Spring Crayfish), is a narrow-ranged endemic occurring in the Ozark Highlands of northern Arkansas and southern Missouri and is under consideration by the U.S. Fish and Wildlife Service (USFWS) for listing under the Endangered Species Act (ESA).  Populations of F. marchandi are limited to small streams on the eastern side of the Spring River drainage . Population genetics indicate two main clades of F. marchandi in the upper vs lower reaches of the Spring River drainage, suggesting these populations be given Evolutionary Significant Unit status. In addition to F. marchandi being rare, imperiled, and petitioned for listing, an invasive species, Faxonius neglectus (Ringed Crayfish), now occurs in high numbers in portions of the Spring River drainage and is spreading. Abiotic disturbances can facilitate the establishment and spread of invasive species, as well as alter their ecological impacts. Stream drying is a frequent disturbance in the Ozark Highlands of Arkansas and Missouri, and recent research has demonstrated that stream drying may play a role in the effective establishment of F. neglectus and the subsequent displacement of F. eupunctus. However, no studies have examined effects of F. neglectus or drought on F. marchandi. Based on our previous research, we hypothesize that F. marchandi populations are at risk due to small geographic range and are susceptible to invasion by F. neglectus.  We also hypothesize that drying and intermittent streams may act as refuges for F. marchandi.

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Landscape- and local-scale habitat influences on distribution and abundance of the crayfish Faxonius eupunctus, Faxonius wagneri and Faxonius roberti in the Spring River, Strawberry River and Eleven Point River drainages

Crayfish are extremely important in most freshwater systems, typically acting as keystone species.  Faxonius eupunctus was already a rare, endemic that occurs in the Ozark Highlands of Arkansas and Missouri and was under consideration by the U.S. Fish and Wildlife Service for listing under the Endangered Species Act.  However, recent research has indicated F. eupunctus consists of three separate species: one species occurring in the upper Eleven Point River (Faxonius eupunctus), one in the lower Eleven Point River (Faxonius wagneri), and one in the Spring River and Strawberry River drainages (Faxonius roberti).  Previous research by our team has examined factors affecting habitat use, selection, distribution and abundance of F. roberti in the Spring River drainage, as well as factors affecting habitat use, selection, distribution and abundance of the F. eupunctus complex as a whole.  However, little, if any, research has examined factors affecting habitat use, selection, distribution and abundance of these newly described species within their native ranges.  We propose to determine landscape- and local-scale factors affecting habitat use, selection, distribution and abundance of F. eupunctus, F. roberti and F. wagneri by modeling species distribution then probabilistically sampling stream sites from their known range.  We will also examine streambank erosion and instability in the study area and relate this, along with other environmental factors, to F. eupunctus, F. roberti and F. wagneri distribution and abundance.  It is important for managers to understand the status and threats to SGCN crayfish species, especially F. eupunctus, F. roberti and F. wagneri, given that they are geographically restricted and potentially susceptible to anthropogenic and natural disturbance.  Information gained here will ultimately be used to make decisions regarding the conservation of F. eupunctus, F. roberti and F. wagneri, and will inform decisions regarding other species that are potentially at risk from similar threats (e.g., Cambarus hubbsi, Faxonius meeki, Faxonius williamsi, Faxonius luteus, Faxonius punctimanus, Faxonius ozarkae, Faxonius neglectus chaeondactylus).