Northwestern Alabama Research Articles

Discussion of infrasonic detection of tornadoes in the Southeastern United States

It has been established that tornadoes emit an infrasonic signal that is regularly detected in the 1 to 10 Hz band, although the actual band is expected to be wider. The physical mechanism through which this signal is generated is not yet fully understood and is the subject of current research. Here we discuss some of our experimental efforts, past and present. During the tornado seasons of 2017, 2018, and 2019, we deployed a network of infrasound sensor arrays in northern Alabama, southern Tennessee, and northwestern Georgia. We performed detailed analysis of one particular storm front that spawned at least eight identified tornadoes in northwestern Alabama during its passage. For that storm we find that when propagation modeling and wind noise analyses suggest that the signal should have been detected at a given array it always was. A long term monitoring effort is now underway in Mississippi. The Mississippi network deployment strategy relied on statistical analyses of tornado touchdown probability, signal transmission loss, and local wind noise studies. The network and array design for our Mississippi network was heavily informed by our experiences in Alabama and, we believe, represents the current state-of-the-art. In this presentation we will give an overview of what was learned from our previous deployments in Alabama, what strategies were used for the current deployment in Mississippi, and the current state of our data collection and analysis.

Distribution and Status of Freshwater Mussels in the Bear Creek Watershed, Mississippi

Bear Creek is a tributary of the Tennessee River in northwestern Alabama and northeastern Mississippi. The watershed supports a diverse freshwater mussel assemblage including several species of conservation concern. We conducted a mussel survey at 55 sites in the Mississippi portions of Bear Creek and its largest tributary, Cedar Creek, during September and October 2020. We found a total of 30 species, of which 25 were represented by live individuals. The invasive Asian Clam, Corbicula fluminea, was widespread in the watershed, but we found no evidence of Zebra Mussel, Dreissena polymorpha. Notable species found live included two federally endangered species, Cumberlandian Combshell, Epioblasma brevidens and Slabside Pearlymussel, Pleuronaia dolabelloides; one federally threatened species, Rabbitsfoot, Theliderma cylindrica; and two state endangered species. In addition, we report the first documented occurrence of the Mountain Creekshell, Villosa vanuxemensis, in Mississippi. Mussel abundance and species richness were low at most sites in the watershed, but the upper portion of Bear Creek had the highest mussel abundance and species richness. We compare our results with previous surveys in the watershed and discuss conservation issues pertinent to the Bear Creek mussel fauna.

Characteristics and Use Patterns of Outdoor Recreationists on Public Lands in Alabama—Case Study of Bankhead National Forest and Sipsey Wilderness Area

Like many other states in south-east USA, Alabama is blessed with a high percentage of natural areas. These areas support vital nature tourism and the outdoor recreation sector. This study was undertaken at the Bankhead National Forest (BNF) and Sipsey Wilderness Area (SWA), significant hubs for outdoor recreation in northwestern Alabama. The goal of this study was to collect baseline information that could be used to develop tools and strategies for increasing the diversity of users participating in outdoor recreation at BNF/SWA. A pretested questionnaire was administered to visitors at eight outdoor recreation sites in the BNF/SWA. Adults encountered at study locations were invited, after their visit, to participate in the study. The study found that (a) the majority of visitors to the BNF/SWA were Caucasians and the least encountered race was African American; (b) the most common reason for visiting BNF/SWA was for family outings, whereas activities with friends or coworkers were the second most important reason for visiting; (c) hiking (39.6%), camping (29.1%), picnicking (23.3%), and horseback riding (22.5%) were the most popular outdoor recreation activities pursued by visitors. It was concluded that a study aimed at identifying the constraints which negatively impact the use of the BNF/SWA by minorities should be a critical step in the process of trying to diversify the BNF/SWA’s user base. Increased efforts must be made to identify the reasons for the low usage of the BNF/SWA by minorities.

Full Waveform Ambient Noise Tomography for the Northern Mississippi Embayment

AbstractWe use seismic ambient noise data recorded by broadband stations around the northern Mississippi Embayment to develop a three‐dimensional shear wave velocity model with full waveform inversion. Empirical Green's functions at periods between 8 and 40s are extracted using a data processing flow based on the continuous wavelet transform. Synthetic waveforms are calculated with an isotropic model through a Graphics Processor Unit‐enabled, collocated finite‐difference code. Starting from the Central United States Velocity Model, the shear wave velocity is iteratively updated with sensitivity kernels constructed using the adjoint method. Several mid‐crustal velocity variations are related to major geological features including the Mississippi Valley graben (MVG), the Ouachita thrust belt, and the Missouri batholith. An intrusion is imaged in northwestern Alabama, coincident with a previously unexplained gravity high. A major change in mid‐crustal velocity occurs across the MVG; much higher velocity crust is present southeast of the graben than northwest. The high velocities are attributed to numerous igneous intrusions, possibly related to formation of the Granite‐Rhyolite province. A strength contrast produced by the change in mid‐crustal velocities may have facilitated formation of the younger, shallower MVG, as external stresses became tensional during Iapetus rifting. The rift pillow is interpreted as the deeper expression of the high velocity crust. Low velocity crust is present below southern Missouri starting at a depth of roughly 20 km. The boundary between the low velocity crust and higher velocity crust to the south and east is sharp and coincides with the Nd‐line.

Amphibian and reptile responses to thinning and prescribed burning in mixed pine-hardwood forests of northwestern Alabama, USA

We evaluated the response of amphibians and reptiles to two levels of prescribed burning and three levels of thinning using a field experiment consisting of a before–after, control-impact, and factorial complete block design over a four year period in the William B. Bankhead National Forest located in northwestern Alabama. We captured 2643 individuals representing 47 species (20 amphibians and 27 reptiles) during 3132 trap nights. Pre-treatment captures varied widely for both amphibians and reptiles among the stands designated for management, which was likely due to forest structural changes caused by tree mortality resulting from Southern Pine Beetle (Dendroctonus frontalis) infestations. Within each amphibian and reptile species assemblage, we observed species-specific associations with specific treatments and environmental characteristics. In regards to individual species responses, Eastern Fence Lizards (Sceloporus undulatus) increased in thin-with-burn treatments and Green Anoles (Anolis carolinensis) tended to increase in all thinned stands. North American Racers (Coluber constrictor) increased in thin-only plots primarily during the second post-treatment year. Mississippi Slimy Salamander (Plethodon mississippi) captures tended to decrease in all treatment stands throughout the study period, which may been due to either drier environmental conditions during post-treatment sampling or natural population cycling. Pool-breeding amphibian captures were more likely related to the hydroperiod of aquatic breeding environments within 290m of survey locations rather than forest treatments. Our results illustrate that forest restoration through tree thinning can positively influence certain reptile species with limited impacts on amphibians in upland, pine-dominated forests of northern Alabama. However, as our forest stands are scheduled to be burned every 3–5years, continued monitoring is necessary to understand the impacts of repeated disturbances.

Upper crustal structure of Alabama from regional magnetic and gravity data: Using geology to interpret geophysics, and vice versa

Aeromagnetic and gravity data sets obtained for Alabama (United States) have been digitally merged and filtered to enhance upper-crustal anomalies. Beneath the Appalachian Basin in northwestern Alabama, broad deep-crustal anomalies of the continental interior include the Grenville front and New York–Alabama lineament (dextral fault). Toward the east and south, high-angle discordance between the northeast-trending Appalachians and the east-west–trending wedge of overlapping Mesozoic and Cenozoic Gulf Coastal Plain sediments reveals how bedrock geophysical signatures progressively change with deeper burial. High-frequency magnetic anomalies in the Appalachian deformed domain (ADD) correspond to amphibolites and mylonites outlining terranes, while broader, lower-amplitude domains include Paleozoic intrusive bodies and Grenville basement gneiss. Fundamental ADD structures (e.g., the Alexander City, Towaliga, and Goat Rock–Bartletts Ferry faults) can be traced southward beneath the Gulf Coastal Plain to the suture with Gondwanan crust of the Suwannee terrane. Within the ADD, there is clear magnetic distinction between Laurentian crust and the strongly linear, high-frequency magnetic highs of peri-Gondwanan (Carolina-Uchee) arc terranes. The contact (Central Piedmont suture) corresponds to surface exposures of the Bartletts Ferry fault. ADD magnetic and gravity signatures are truncated by the east-west–trending Altamaha magnetic low associated with the Suwannee suture. Arcuate northeast-trending magnetic linears of the Suwannee terrane reflect internal structure and Mesozoic failed-rift trends. Geophysical data can be used to make inferences on surface and subsurface geology and vice versa, which has applicability anywhere that bedrock is exposed or concealed beneath essentially non-magnetic sedimentary cover.

Distribution of arsenic, selenium, and other trace elements in high pyrite Appalachian coals: Evidence for multiple episodes of pyrite formation

Abstract Pennsylvanian coals in the Appalachian Basin host pyrite that is locally enriched in potentially toxic trace elements such as As, Se, Hg, Pb, and Ni. A comparison of pyrite-rich coals from northwestern Alabama, eastern Kentucky, and West Virginia reveals differences in concentrations and mode of occurrence of trace elements in pyrite. Pyrite occurs as framboids, dendrites, or in massive crystalline form in cell lumens or crosscutting veins. Metal concentrations in pyrite vary over all scales, from microscopic to mine to regional, because trace elements are inhomogeneously distributed in the different morphological forms of pyrite, and in the multiple generations of sulfide mineral precipitates. Early diagenetic framboidal pyrite is usually depleted in As, Se, and Hg, and enriched in Pb and Ni, compared to other pyrite forms. In dendritic pyrite, maps of As distribution show a chemical gradient from As-rich centers to As-poor distal branches, whereas Se concentrations are highest at the distal edges of the branches. Massive crystalline pyrite that fills veins is composed of several generations of sulfide minerals. Pyrite in late-stage veins commonly exhibits As-rich growth zones, indicating a probable epigenetic hydrothermal origin. Selenium is concentrated at the distal edges of veins. A positive correlation of As and Se in pyrite veins from Kentucky coals, and of As and Hg in pyrite-filled veins from Alabama coals, suggests coprecipitation of these elements from the same fluid. In the Kentucky coal samples (n = 18), As and Se contents in pyrite-filled veins average 4200 ppm and 200 ppm, respectively. In Alabama coal samples, As in pyrite-filled veins averages 2700 ppm (n = 34), whereas As in pyrite-filled cellular structures averages 6470 ppm (n = 35). In these same Alabama samples, Se averages 80 ppm in pyrite-filled veins, but was below the detection limit in cell structures. In samples of West Virginia massive pyrite, As averages 1700 ppm, and Se averages 270 ppm (n = 24). The highest concentration of Hg (≤ 102 ppm) is in Alabama pyrite veins. Improved detailed descriptions of sulfide morphology, sulfide mineral paragenesis, and trace-element concentration and distribution allow more informed predictions of: (1) the relative rate of release of trace elements during weathering of pyrite in coals, and (2) the relative effectiveness of various coal-cleaning procedures of removing pyrite. For example, trace element-rich pyrite has been shown to be more soluble than stoichiometric pyrite, and fragile fine-grained pyrite forms such as dendrites and framboids are more susceptible to dissolution and disaggregation but less amenable to removal during coal cleaning.

Paleoindian and Archaic Activities at Dust Cave, Alabama: The Secular and the Sacred

Located in the Tennessee River valley of northwestern Alabama, the site of Dust Cave was occupied from the Late Pleistocene through the Mid-Holocene. Over four meters of deposits in the cave vestibule have preserved a record of a transforming climate, local geomorphology and the human responses to these changes through time. A synthesis of the floral, faunal, lithic, and feature data in combination with the information from a bone cache, and dog and human burials allow for an overview of life during the occupation of the cave.

Taxonomic Revision of Cave Crayfish in the Genus Cambarus, Subgenus Aviticambarus (Decapoda: Cambaridae) with Descriptions of Two New Species, C. Speleocoopi and C. Laconensis, Endemic to Alabama, U.S.A.

Abstract As historically recognized, three stygobitic species of the subgenus Aviticambarus, genus Cambarus inhabit Mississippian limestone caves along the southern edge of the Southern Appalachians and Highland Rim in southeastern Tennessee and Northern Alabama, U.S.A. These include Cambarus hamulatus, C. jonesi, and C. veitchorum. All stygobitic members of the genus Procambarus inhabit caves in Florida, Cuba, and Mexico with exception of P. pecki (in the monotypic subgenus Remoticambarus), which exists in only three caves with C. jonesi in Northwestern Alabama. It was hypothesized that Procambarus pecki was derived from a primitive Procambarus stock that gave rise to the genera Cambarus and Orconectes based on the morphological shapes of the gonopods. Excluding the unsampled rare C. veitchorum, here we present 16S rDNA phylogenetic evidence, contrary to former morphological-based inferences, for the recognition of five distinct Aviticambarus lineages including P. pecki. Cambarus laconensis is a new spec...

Prevalence of and risk factors associated with shedding of Cryptosporidium felis in domestic cats of Mississippi and Alabama

The prevalence of and risk factors associated with the shedding of cryptosporidial oocysts were determined for domestic cats in northeastern Mississippi and northwestern Alabama. Cryptosporidial oocysts were found in a single fecal samples from 30 of 250 cats using a centrifugal concentration technique followed by an immunofluorescent assay. The odds of a cat shedding oocysts were increased when another cat shedding oocysts was present in the household. Logistic regression analysis showed only concurrent shedding of Giardia cysts to be significantly associated with the presence of Cryptosporidium oocysts in the feces. Oocysts from 12 cats were successfully genotyped, based on sequencing of a fragment of the 18S rRNA gene, all isolates were Cryptosporidium felis.

Three new percid fishes (Percidae: Percina) from the Mobile Basin drainage of Alabama, Georgia, and Tennessee

Three new species of Percina are described from upland drainages of the Mobile Basin. Two of the three species are narrowly distributed: P. kusha, the Bridled Darter, is currently known only from the Conasauga River drainage in Georgia and Tennessee and Etowah River drainage in Georgia, both tributaries of the Coosa River, and P. sipsi, the Bankhead Darter, which is restricted to tributaries of Sipsey Fork of the Black Warrior River in northwestern Alabama. The third species, P. smithvanizi, the Muscadine Darter, occurs above the Fall Line in the Tallapoosa River drainage in eastern Alabama and western Georgia. In a molecular analysis using mitochondrial cytochrome b sequence data, P. kusha and P. smithvanizi were recovered as sister species, while Percina sipsi was recovered in a clade consisting of P. aurolineata (P. sciera + P. sipsi). Two of the three species, P. kusha and P. sipsi, are considered to be imperiled species and are in need of conservation actions to prevent their extinction. Description of these three darters increases the number of described species of Percina to 44. Sixteen are known to occur in the Mobile Basin, including nine that are endemic.

Genotypic Analysis of Giardia Duodenalis in Domestic Cats

Background:Giardia duodenalis is an intestinal flagellated protozoan that affects many mammalian species often causing severe diarrheal disease. Several different genotypes have been identified (Assemblages A‐G). Most isolates recovered from domestic cats have been assigned to either Assemblage A, the zoonotic form of the parasite, or Assemblage F, identified thus far only in cats. Genotypic variation within G. duodenalis may influence clinical presentation and course of disease. Therefore, host‐adapted genotypes may not be responsible for diarrheal disease (eg, Assemblage F in cats).Hypothesis:Multiple Giardia genotypes will be present in domestic cats, including Assemblage F, which will not be correlated with clinical signs.Animals:250 domestic cats from eastern Mississippi and northwestern Alabama.Methods:Prevalence survey. Fecal samples evaluated for cysts using a centrifugation concentration technique and a commercially available direct immunoflourescent antibody kit. Giardia isolates were characterized by PCR amplification and sequencing of the glutamate dehydrogenase gene.Results:Both Assemblage A‐I (6/17) and Assemblage F (11/17) were identified. Although Assemblage was significantly associated with age and housing, no association was detected between Assemblage and a variety of other factors including the presence of gastrointestinal signs (acute vomiting, diarrhea, and constipation).Conclusions and Clinical Importance: The presence of diarrhea in domestic cats with Giardia cannot be used as a predictor of the presence of zoonotic genotypes in animals within the study area. Although Assemblage A was associated with age and housing, veterinarians should consider any isolation of Giardia from domestic cats as potentially zoonotic.

A Survey of Terrestrial Gastropods of the Sipsey Wilderness (Bankhead National Forest), Alabama

A survey of the terrestrial mollusks of the Sipsey Wilderness Area, Bankhead National Forest, in northwestern Alabama was conducted from August 2003 to May 2004. A total of 15 sites were sampled across a number of different habitat and vegetation types found within the area. A total of 50 species were found, representing 14 families and 30 genera, including 58 new county and 2 new state records. This represents a significant increase in the known diversity of the area based on a preliminary survey conducted in the 1960s, which yielded only six species. The current survey highlights the need for more detailed survey work across Alabama and the southeastern United States.

Particle-size and analytical considerations in the mineral-magnetic interpretation of soil loss from cultivated landscapes

Prior research has highlighted the potential for using soil magnetism as a rapid estimator of total cumulative soil loss on cultivated land. In this study, the influences of particle size, choice of magnetic measurement and initial conditions on a proposed model linking surface soil magnetism and soil loss are described and evaluated. Output model curves are generated for several parameter sets corresponding to different model assumptions and physical scenarios. Output is also compared to a new high-resolution surfacial magnetism data set from a cultivated site, Gilbert Farm in northwestern Alabama (USA), to further evaluate the model. Magnetic susceptibility values at Gilbert Farm range from 150 to 220 (×10−8) m3 kg−1 in a control soil profile. The original model output ranges from 180 to 192 (×10−8) m3 kg−1 and many magnetism values in the cultivated area fall outside this range. Introduction of a particle-size sorting correction factor decreases the range of output values and results in even greater numbers of out-of-range observations. However, there is evidence suggesting that particle-size distributions in the upper soil at this site are not strongly affected by differences in water erosion mechanism. Lower tillage depths cause magnetic susceptibility values to come in range, but may be unrealistic and create a twin-value problem for complex magnetic profiles. Use of the remanence (SIRM)/volume susceptibility (κlf) ratio profile, with values ranging from 35 to 120 mA m−1/10−5 SI, instead of magnetic susceptibility as used in the original model, was found to eliminate out-of-range and twin value. Anomalous magnetism values were identifiable and treatable on the high resolution magnetism maps, but other types of natural spatial variation remain at issue.

Modes of occurrence of mercury and other trace elements in coals from the warrior field, Black Warrior Basin, Northwestern Alabama

The mineralogic residence and abundance of trace metals is an important environmental issue. Data from the USGS coal quality database show that potentially toxic elements, including Hg, As, Mo, Se, Cu, and Tl are enriched in a subset of coal samples in the Black Warrior Basin of Alabama, USA. Although the coal as-mined typically is low in these elements, localized enrichments occur in high-pyrite coals and near faults. Microscopic analyses demonstrate that the residence of these elements is dominantly in a late-stage pyrite associated with structurally disrupted coal. Further, our data suggest addition of Hg to the coal matrix as well. The source of these trace elements was hydrothermal fluids driven into the Black Warrior Basin by Alleghanian age tectonism.

Particle-size and analytical considerations in the mineral-magnetic interpretation of soil loss from cultivated landscapes

Prior research has highlighted the potential for using soil magnetism as a rapid estimator of total cumulative soil loss on cultivated land. In this study, the influences of particle size, choice of magnetic measurement and initial conditions on a proposed model linking surface soil magnetism and soil loss are described and evaluated. Output model curves are generated for several parameter sets corresponding to different model assumptions and physical scenarios. Output is also compared to a new high-resolution surfacial magnetism data set from a cultivated site, Gilbert Farm in northwestern Alabama (USA), to further evaluate the model. Magnetic susceptibility values at Gilbert Farm range from 150 to 220 (×10 −8) m 3 kg −1 in a control soil profile. The original model output ranges from 180 to 192 (×10 −8) m 3 kg −1 and many magnetism values in the cultivated area fall outside this range. Introduction of a particle-size sorting correction factor decreases the range of output values and results in even greater numbers of out-of-range observations. However, there is evidence suggesting that particle-size distributions in the upper soil at this site are not strongly affected by differences in water erosion mechanism. Lower tillage depths cause magnetic susceptibility values to come in range, but may be unrealistic and create a twin-value problem for complex magnetic profiles. Use of the remanence (SIRM)/volume susceptibility ( κ lf) ratio profile, with values ranging from 35 to 120 mA m −1/10 −5 SI, instead of magnetic susceptibility as used in the original model, was found to eliminate out-of-range and twin value. Anomalous magnetism values were identifiable and treatable on the high resolution magnetism maps, but other types of natural spatial variation remain at issue.

Status of the Federally Endangered Alabama Cavefish, Speoplatyrhinus Poulsoni (Amblyopsidae), in Key Cave and surrounding Caves, Alabama

Speoplatyrhinus poulsoni, the Alabama cavefish, is a federally endangered stygobitic fish that is restricted to Key Cave in northwestern Alabama. Due to the low abundance of this species and the continuous threats to the cave's recharge area, we surveyed Key Cave from 1992 to 1997. Alabama cavefish were present in five different pools and had numbers comparable to previous surveys performed in the 1970's and 1980's. Three different size classes were observed, indicating recruitment is occurring. These data suggest that the population is relatively stable, but future monitoring is recommended. The Alabama cavefish is an endangered species and is extremely difficult to capture, therefore any marking program to accurately estimate the population size is unlikely. A single specimen of Typhlichthys subterraneus was captured in Key Cave. This falsifies the previous assumption that these two species are allopatric. Because of this discovery, we resurveyed seven caves in the area around Key Cave for additional populations of S. poulsoni. These caves had either known populations of T. subterraneus or unidentified cavefish. No additional populations of S. poulsoni were discovered, but further investigation is warranted. The Key Cave National Wildlife Refuge was established in the high recharge area of Key Cave to protect this habitat, yet threats to the groundwater continue from encroaching urbanization.

Use of mineral magnetic measurements to investigate soil erosion and sediment delivery in a small agricultural catchment in limestone terrain

Understanding sediment delivery at the hillslope scale requires information on the spatial distributions and magnitudes of erosion and deposition. Empirical models such as the RUSLE may be useful for predicting erosion, but are poorly suited for quantifying deposition. Cesium-137 (Cs-137) is useful for quantifying both erosion and deposition, but is costly to inventory over a large area, and directly gauges soil redistribution only for recent decades. The use of rapidly acquired magnetic measurements represents a relatively new potential means of mapping and measuring soil redistribution. In this study, variations in surface magnetism are analyzed to determine patterns of erosion and sedimentation in a small agricultural catchment in northwestern Alabama (USA). Magnetic indicators of erosion are combined with published soil morphology, Cs-137 and short-term suspended sediment data from this former experimental watershed to evaluate long-term sediment delivery. All magnetic parameters measured could be related to soil erosion, although their patterns in space are not identical. Magnetic evidence suggests approximately 30 cm of soil loss on the steepest mid-slope portions of the catchment. Distributing soil loss across space according to magnetic patterns gives average long-term values lower than a prior estimate based on Cs-137 data. Long-term sediment delivery calculated using soil morphology to determine depositional volume ranges up to 45% depending on the magnetic parameter used to index soil loss, and assumptions regarding deposit geometry. These results suggest the need for continued refinement of magnetic techniques for purposes of erosion model validation and general sediment tracing applications.

Possible Neoproterozoic-early Paleozoic grabens in Mississippi, Alabama, and Tennessee

Low-intensity magnetic and negative gravity anomalies in northern Mississippi, north-western Alabama, and western Tennessee are viewed as being similar to the magnetic and gravity low associated with the Mississippi Valley graben. The anomalies are interpreted as shallow grabens, and it is proposed that the grabens, like the Mississippi Valley graben, resulted from northwest-southeast extension during Neoproterozoic-early Paleozoic fragmentation of Laurentia. If real, the grabens indicate that extension affected a larger part of Laurentia than has been previously documented. They imply hitherto unsuspected oil and gas potential and, if the area is coupled to the stress field affecting the Mississippi Valley graben, represent structures that warrant evaluation for seismic risk.

Vertebral arthritis and physical activities in the prehistoric southeastern United States.

Vertebral arthritis is examined in a prehistoric Native American sample from northwestern Alabama. Both osteophytosis (OP) of the vertebral bodies and osteoarthritis (OA) of the apophyseal facets are highest in the lumbar vertebrae, followed by the cervical and thoracic segments, although differences are much more striking in OP. OA is bilaterally asymmetric, with greater prevalence on the right side in the upper thoracic region. Much of the patterning seen in arthritis in this and other samples is due to the stresses imposed by spinal curvature and weight-bearing due to our erect posture. In addition, handedness is the probable cause of asymmetry in OA. However, the high levels of cervical OP are unexpected, and may be due to use of the tumpline in carrying burdens.