White River Research Articles

Cryptic Methane-Cycling by Methanogens During Multi-Year Incubation of Estuarine Sediment

As marine sediments are buried, microbial communities transition from sulfate-reduction to methane-production after sulfate is depleted. When this biogenic methane diffuses into the overlying sulfate-rich sediments, it forms a sulfate-methane transition zone (SMTZ) because sulfate reducers deplete hydrogen concentrations and make hydrogenotrophic methanogenesis exergonic in the reverse direction, a process called the anaerobic oxidation of methane (AOM). Microbial participation in these processes is often inferred from geochemistry, genes, and gene expression changes with sediment depth, using sedimentation rates to convert depth to time. Less is known about how natural sediments transition through these geochemical states transition in real-time. We examined 16S rRNA gene amplicon libraries and metatranscriptomes in microcosms of anoxic sediment from the White Oak River estuary, NC, with three destructively sampled replicates with methane added (586-day incubations) and three re-sampled un-amended replicates (895-day incubations). Sulfate dropped to a low value (∼0.3 mM) on similar days for both experiments (312 and 320 days, respectively), followed by a peak in hydrogen, intermittent increases in methane-cycling archaea starting on days 375 and 362 (mostly Methanolinea spp. and Methanosaeta spp., and Methanococcoides sp. ANME-3), and a methane peak 1 month later. However, methane δ13C values only show net methanogenesis 6 months after methane-cycling archaea increase and 4 months after the methane peak, when sulfate is consistently below 0.1 mM and hydrogen increases to a stable 0.61 ± 0.13 nM (days 553–586, n = 9). Sulfate-reducing bacteria (mostly Desulfatiglans spp. and Desulfosarcina sp. SEEP-SRB1) increase in relative abundance only during this period of net methane production, suggesting syntrophy with methanogens in the absence of sulfate. The transition from sulfate reduction to methane production in marine sediments occurs through a prolonged period of methane-cycling by methanogens at low sulfate concentrations, and steady growth of sulfate reducers along with methanogens after sulfate is depleted.

Late Holocene cryptotephra and a provisional 15 000-year Bayesian age model for Cascade Lake, Alaska

Abstract. Multiple chronometers can be employed for dating Holocene palaeoenvironmental records, each with its own inherent strengths and weaknesses. Radiocarbon dating is one of the most widely used techniques for producing chronologies, but its application at high-latitude sites can sometimes be problematic. Here, cryptotephra were identified in a core from Cascade Lake, Arctic Alaska, and used to identify and resolve an age bias in Late Holocene radiocarbon dates from the top 1.42 m of the sediment sequence. Identifiable geochemical populations of cryptotephra are shown to be present in detectable concentrations in sediment from the north flank of the Brooks Range for the first time. Major-element glass geochemical correlations are demonstrated between ultra-distal cryptotephra and reference samples from the Late Holocene caldera-forming eruption of Opala, Kamchatka, as well as three eruptions in North America: the White River Ash (northern lobe), Ruppert tephra and the Late Holocene caldera-forming eruption of Aniakchak. The correlated ages of these cryptotephra provide evidence for an old-carbon effect and support preliminary palaeomagnetic secular variation (PSV) correlated ages reported for Cascade Lake. Chronological data from Cascade Lake were then combined using a Bayesian approach to generate an age–depth model that extends back through the Late Holocene and provisionally to 15 000 cal yr BP.

Increased flooded area and exposure in the White Volta river basin in Western Africa, identified from multi-source remote sensing data

Accurate information on flood extent and exposure is critical for disaster management in data-scarce, vulnerable regions, such as Sub-Saharan Africa (SSA). However, uncertainties in flood extent affect flood exposure estimates. This study developed a framework to examine the spatiotemporal pattern of floods and to assess flood exposure through utilization of satellite images, ground-based participatory mapping of flood extent, and socio-economic data. Drawing on a case study in the White Volta basin in Western Africa, our results showed that synergetic use of multi-temporal radar and optical satellite data improved flood mapping accuracy (77% overall agreement compared with participatory mapping outputs), in comparison with existing global flood datasets (43% overall agreement for the moderate-resolution imaging spectroradiometer (MODIS) Near Real-Time (NRT) Global Flood Product). Increases in flood extent were observed according to our classified product, as well as two existing global flood products. Similarly, increased flood exposure was also observed, however its estimation remains highly uncertain and sensitive to the input dataset used. Population exposure varied greatly depending on the population dataset used, while the greatest farmland and infrastructure exposure was estimated using a composite flood map derived from three products, with lower exposure estimated from each flood product individually. The study shows that there is considerable scope to develop an accurate flood mapping system in SSA and thereby improve flood exposure assessment and develop mitigation and intervention plans.

Geologic Map of the Woodrock Quadrangle, Sheridan and Big Horn Counties, Wyoming

Here we present the results of detailed (1:24,000 scale) mapping of the Woodrock 7.5 Minute Quadrangle Wyoming, which mainly consists of Archean basement rocks of the Laramide Bighorn uplift. Our focus was on the Archean geology of the Laramide age Bighorn uplift. Isotopic age determinations (U-Pb on zircon) were conducted at the University of Arizona LaserChron Center. Our work revealed the presence of four different components of the batholith. The oldest unit is a ~2880 Ma foliated Lookout Mountain Granodiorite that occurs in the southern part of the quadrangle in the vicinity of Bruce and Lookout Mountains. The ~2775 Black Mountain Tonalite occurs in the northeastern part of the quadrangle. The age of the Black Mountain Tonalite and Lookout Mountain Granodiorite overlap but the units are distinct in terms of structure and lithology so they were mapped separately. The central part of the quadrangle is underlain by the massive, ~2860 Ma Taylor Mine Granite. This unit is poorly exposed and variable in texture. The youngest unit is the ~2850 Ma Owen Creek Alkali Feldspar Granite, which occurs in the western part of the quadrangle. Mafic dikes of variable geometry, texture and age cross-cut the quartzofeldspathic rocks. Less than 25 m of poorly exposed Cambrian Flathead Sandstone occurs along the extreme western margin of the quadrangle. We discovered as much as 30 m of Oligocene White River Formation strata occur as terrace deposits along the western side of the Tongue River in the central part of the quadrangle. The White River strata are poorly exposed and consist of thin bedded tuffaceous sandstone and massive conglomerate that are light colors and include as clasts Paleozoic carbonate and Archean basement rocks. Less than 50 m of Pinedale-age glacial tills occur along the upper Tongue River in the southern part of the Quadrangle, forming hummocky, poorly-drained topography. Quaternary alluvium occurs along some of the larger streams.

“El Viudo De Pescado”

“El Viudo De Pescado”

The Life Histories of Intermediate Hosts and Parasites of Schistosoma haematobium and Schistosoma mansoni in the White Nile River, Sudan.

Background: The epidemiology of schistosomiasis transmission varies depending on the circumstances of the surrounding water bodies and human behaviors. We aimed to explore cercarial emergence patterns from snails that are naturally affected by human schistosomiasis and non-human trematodes. In addition, this study aimed to explore how schistosomiasis infection affects snail survival, reproduction, and growth. Methods: We measured the survival rate, fecundity, and size of Biomphalaria pfeifferi snails and the cercarial rhythmicity of S. haematobium and S. mansoni. The number of egg masses, eggs per egg mass, and snail deaths were counted for 7 weeks. The survival rate and cumulative hazard were assessed for infected and non-infected snails. Results: S. haematobium and S. mansoni cercariae peaked at 9:00–11:00 a.m. Infection significantly reduced the survival rate of B. pfeifferi, which was 35% and 51% for infected and non-infected snails, respectively (p = 0.02), at 7 weeks after infection. The hazard ratio of death for infected snails compared to non-infected snails was 1.65 (95% confidence interval: 1.35–1.99; p = 0.01). Conclusions: An understanding of the dynamics of schistosomiasis transmission will be helpful for formulating schistosomiasis control and elimination strategies. Cercarial rhythmicity can be reflected in health education, and the reproduction and survival rate of infected snails can be used as parameters for developing disease modeling.

On the Primitive Image and Root Seeking Consciousness in Root Seeking Novels

The ideological trend of root seeking literature is an influential literary movement in the mid-1980s, but the literary circles have always had different views on root seeking literature. There is no unified concept about the theoretical concepts of root seeking, such as "root", "culture", "tradition" and "fracture", which makes the root seeking novels have "many semantic fields" and the tendency of various cultural interpretation, especially the differences on "traditional culture" are very obvious. Therefore, it is particularly important to clarify the relationship between root seeking novels and traditional culture, so as to deeply grasp the cultural meaning of root seeking novels. It is worth noting that the traditional expression of root seeking writers is based on the connection with the contemporary humanistic environment, and conceives the original natural picture of all things with the help of traditional culture, showing the worship and admiration of the original nature, the direction of freedom and independence, and the romantic concept of survival and primitive consciousness. Based on the "primitive image" proposed by Zhao Peilin in the origin of Xing, this paper analyzes and explains the spiritual and mysterious image codes in the representative works of root seeking novels White Deer Plain, tree king and northern river, and probes into the traditional cultural concepts and root seeking consciousness transmitted by the three primitive images of "deer", "tree" and "River".

Rapid Molecular Determination of Sex for Western North American Chub (Gila spp.)

AbstractGathering sex data is frequently a complicated matter for fish species that lack sexually dimorphic traits. Secondary sexual characteristics are cryptic or nonexistent in many minnows (Cyprinidae) during early life stages or outside of the breeding season, which may require lethal methods for determining sex. This complicates many conservation actions and population genetic studies, including (1) the development of hatchery broodstocks for threatened and endangered species, (2) sex ratio determination in wild populations, (3) the influence of sex ratio on the effective population size estimates, and (4) limitations on the implementation of genetic tagging and parentage assignment in wild populations. Here, we remedy this issue for four western North American chub species (Gila spp.) through restriction‐site‐associated DNA sequencing of Bonytail G. elegans, which identified a single locus indicating an XY sex determination system and no candidate loci consistent with a WZ system. This locus cross‐amplified in three additional Gila species (Chihuahua Chub G. nigrescens, Virgin Chub G. seminuda, and White River Chub G. jordani), although species‐specific differences necessitated the development of three novel primer/probe sets. Real‐time PCR with hydrolysis probe assays was used to genotype sex‐linked single‐nucleotide polymorphisms for each species. The measurement of endpoint fluorescence in a real‐time PCR thermal cycler allowed for rapid and accurate sex genotyping of these species, with accuracy >97% relative to phenotypic sex identification when three PCR replicates were employed. These assays provided high precision, with unanimous results across >87% of the replicates and a majority consensus genotype for 98.6% of the samples. The locus identified herein was conserved across all of the Gila species that we tested (n = 6) and other western North American cyprinids; however, sex‐linked polymorphisms were found only in the four species that are named above. Consequently, this locus has promise for the identification and development of sex‐linked assays for other Gila and closely related cyprinids.

Review: The Bob Ross Experience. Minnetrista Cultural Center, Muncie, Indiana

Review: <i>The Bob Ross Experience</i>. Minnetrista Cultural Center, Muncie, Indiana

A latest Pleistocene and Holocene composite tephrostratigraphic framework for northeastern North America

Lakes and bogs in northeastern North America preserve tephra deposits sourced from multiple volcanic systems in the Northern Hemisphere. However, most studies of these deposits focus on specific Holocene intervals and the latest Pleistocene, providing snapshots rather than a full picture. We combine new data with previous work, supplemented by a broad review of the characteristics and ages of potential source regions and volcanoes, to develop the first composite tephrostratigraphic framework covering the last ∼14,000 years for this region. We report new cryptotephra records from three ombrotrophic peat bogs—Irwin Smith (Michigan), Bloomingdale (New York), and Sidney Bog (Maine)—as well as new analyses and age models from previously reported sites, Nordan's Pond Bog (Newfoundland) and Thin-Ice Pond (Nova Scotia). A new tephra (Iliinsky) from the NGRIP and GRIP ice cores is also presented as it can be correlated to new data from these terrestrial records and helps validate radiocarbon age models. We identify 21 new tephra in addition to the 15 already known, several of which cover the entire region – the White River Ash east, Newberry Pumice, Ruppert (NDN-230), and Mazama. For the first time we find Mount St. Helens Yn (ca. 3660 cal yr BP) and a set P tephra (∼3000–2550 cal yr BP), and confirm the presence of Jala Pumice from Volcan Ceboruco, Mexico, and KS1 from Ksudach volcano, Kamchatka. We describe new “ultra-distal” tephra, including the early Holocene KS2 eruption, and propose correlations to volcanoes Iliinsky and Shiveluch of Kamchatka, and Ushishir of the Kurile Islands. Not all of these tephra represent large eruptions, with several plausible correlations to sub-Plinian events. Using Bayesian age-modeling, we present new age estimates for the newly described tephra, for tephra with previously poor age control, and for several proximal correlatives. Overall, we demonstrate northeastern North America's importance for providing transcontinental linkages between paleoenvironmental records and providing insights into ash distribution from different styles and sizes of eruptions.

Groundwater quality assessment using GIS, the case of Omdurman area, central Sudan

Omdurman area, located west of the River Nile and White Nile is witnessing rapid urban expansion and land use change. Several axial irrigation schemes have developed accelerating the demand for water supply. This indeed, will place more pressure over the available groundwater resources. In order to measure any change of groundwater quality it is necessary to initially evaluate the background condition. This contribution employs a GIS- based Groundwater Quality Index (GQI) which synthesizes different variable water quality data (e.g. Cl-, Na+ and SO42+) by indexing them numerically relative to the World Health Organization (WHO) standards in order evaluate the overall groundwater quality in the study area.The GQI computed for Omdurman area indicated that the water quality is generally high (mean GQI = 90 out of 100) with respect to the WHO standards. Spatially the groundwater quality of the study area increased from the central area in the northeastern direction and decrease in the southeastern direction. This result was interpreted in terms of general groundwater flow, the recharge zone, geology and soil composition. Drilling at close distances and over pumping specially in the central region might create local variations of groundwater flow resulting in mixing of waters of different qualities deteriorating the quality of water in previously safe zones. This is expected due to the low hydraulic gradient (&lt; 0.001) characterizing some parts of the study area as well as the minimum recharge far from the River Nile and the White Nile.

Development and Validation of a Clinical Risk Score to Predict Hospitalization Within 30 Days of Coronavirus Disease 2019 Diagnosis.

ABSTRACTIntroductionEarly identification of patients with coronavirus disease 2019 (COVID-19) who are at risk for hospitalization may help to mitigate disease burden by allowing healthcare systems to conduct sufficient resource and logistical planning in the event of case surges. We sought to develop and validate a clinical risk score that uses readily accessible information at testing to predict individualized 30-day hospitalization risk following COVID-19 diagnosis.MethodsWe assembled a retrospective cohort of U.S. Veterans Health Administration patients (age ≥ 18 years) diagnosed with COVID-19 between March 1, 2020, and December 31, 2020. We screened patient characteristics using Least Absolute Shrinkage and Selection Operator logistic regression and constructed the risk score using characteristics identified as most predictive for hospitalization. Patients diagnosed before November 1, 2020, comprised the development cohort, while those diagnosed on or after November 1, 2020, comprised the validation cohort. We assessed risk score discrimination by calculating the area under the receiver operating characteristic (AUROC) curve and calibration using the Hosmer–Lemeshow (HL) goodness-of-fit test. This study was approved by the Veteran’s Institutional Review Board of Northern New England at the White River Junction Veterans Affairs Medical Center (Reference no.:1473972-1).ResultsThe development and validation cohorts comprised 11,473 and 12,970 patients, of whom 4,465 (38.9%) and 3,669 (28.3%) were hospitalized, respectively. The independent predictors for hospitalization included in the risk score were increasing age, male sex, non-white race, Hispanic ethnicity, homelessness, nursing home/long-term care residence, unemployed or retired status, fever, fatigue, diarrhea, nausea, cough, diabetes, chronic kidney disease, hypertension, and chronic obstructive pulmonary disease. Model discrimination and calibration was good for the development (AUROC = 0.80; HL P-value = .05) and validation (AUROC = 0.80; HL P-value = .31) cohorts.ConclusionsThe prediction tool developed in this study demonstrated that it could identify patients with COVID-19 who are at risk for hospitalization. This could potentially inform clinicians and policymakers of patients who may benefit most from early treatment interventions and help healthcare systems anticipate capacity surges.

Environmentally-induced osmoregulation in Neotropical freshwater stingrays (Myliobatiformes: Potamotrygoninae) after controlling for phylogeny

The osmotic physiology of freshwater stingrays was investigated in fifteen species from white (WW), black (BW), and clearwater (CW) rivers of Brazilian hydrographic basins. Regardless of phylogeny, potamotrygonids collected in the BW (Negro, Jutai, Nhamunda, and Manacapuru rivers), and CW (Tapajos, Parana, Mutum, Demeni, and Branco rivers) exhibited lower levels of osmolytes and plasma osmolality than those from WW (Amazon estuary, Solimoes, and Tarauaca rivers). However, the gill and kidney Na+/K+-ATPase activities were higher in the potamotrygonid species from BW and CW than those from WW. These results may be related to the ability of the potamotrygonids to achieve high ion uptake from ion-poor waters, such as those of BW and/or CW. Additionally, the high kidney Na+/K+-ATPase activity may help to minimize ion loss and generate diluted urine. Thus, diffusional losses of salts are balanced by uptake of ions in the gill, and reabsorption by the kidney. The physiological traits showed a weak phylogenetic signal, which indicates a strong evolutionary convergence. Multivariate analyses revealed that variations in physiological traits has a significant association with the type of water, as well as its physical and chemical characteristics such as electric conductivity and pH. Therefore, the South American Neotropical freshwater stingrays adjust their osmoregulatory mechanisms according to the environment in which they live.

Quantitative Contributions of Climate Change and Human Activities to Vegetation Changes in the Upper White Nile River

Vegetation changes in the Upper White Nile River (UWNR) are of great significance to the maintenance of local livelihoods, the survival of wildlife, and the protection of species habitats. Based on the GIMMS NDVI3g and MODIS normalized difference vegetation index (NDVI) data, the temporal and spatial characteristics of vegetation changes in the UWNR from 1982 to 2020 were analyzed by a Theil-Sen median trend analysis and Mann-Kendall test. The future trend of vegetation was analyzed by the Hurst exponential method. A partial correlation analysis was used to analyze the relationship of the vegetation and climate factors, and a residual trend analysis was used to quantify the influence of climate change and human activities on vegetation change. The results indicated that the average NDVI value (0.75) of the UWNR from 1982 to 2020 was relatively high. The average coefficient of variation for the NDVI was 0.059, and the vegetation change was relatively stable. The vegetation in the UWNR increased 0.013/10 year on average, but the vegetation degradation in some areas was serious and mainly classified as agricultural land. The results of a future trend analysis showed that the vegetation in the UWNR is mainly negatively sustainable, and 62.54% of the vegetation will degrade in the future. The NDVI of the UWNR was more affected by temperature than by precipitation, especially on agricultural land and forestland, which were more negatively affected by warming. Climate change and human activities have an impact on vegetation changes, but the spatial distributions of the effects differ. The relative impact of human activities on vegetation change accounted for 64.5%, which was higher than that of climate change (35.5%). Human activities, such as the large proportion of agriculture, rapid population growth and the rapid development of urbanization were the main driving forces. Establishing a cross-border drought joint early warning mechanism, strengthening basic agricultural research, and changing traditional agricultural farming patterns may be effective measures to address food security and climate change and improve vegetation in the UWNR.

Hydrological Modeling in Agricultural Intensive Watershed: The Case of Upper East Fork White River, USA

Identifying the core hydrological processes of catchments is a critical step for operative hydrological modeling. This study attempts to assess the long-term alterations in streamflow in three adjacent catchments of Upper East Fork White River, Indiana USA, by employing the SWAT hydrological model. The model simulations are spanning from 1980 up to 2015 and distributed in three configurations periods to identify monthly alterations in streamflow. For this purpose, water abstraction, land use, tillage, and agricultural field drainage practices have been incorporated in the model to provide accurate data input. The model setup also integrates spatially disaggregated sectorial water use data from surface and groundwater resources integrating the significant increases of water abstractions mainly for agricultural and public water supply purposes. The land cover of the study area is governed by rotating crops, while agricultural practices and tile drainage are crucial model parameters affecting the regional hydrological balance. Streamflow prediction is based on the SUFI-2 algorithm and the SWAT-CUP interface has been used for the monthly calibration and validation phases of the model. The evaluation of model simulations indicate a progressively sufficient hydrological model setup for all configuration periods with NSE (0.87, 0.88, and 0.88) and PBIAS (14%, −7%, and −2.8%) model evaluation values at the Seymour outlet. Surface runoff/precipitation as well as percolation/precipitation ratios have been used as indicators to identify trends to wetter conditions. Model outputs for the upstream areas, are successful predictions for streamflow assessment studies to test future implications of land cover and climate change.

Depositional patterns of slowly plugging neck cutoffs from core analysis and estimates of bedload transport, White River, Arkansas

AbstractMeander cutoffs and oxbow lakes are very common features of fluvial landscapes that add complexity and diversity to floodplain alluvial architecture and riverine habitats. Following initial cutoff, sediment accumulates within the entrance and exit of the original bend forming plugs that eventually disconnect the abandoned bend from the main channel. While studies have examined the sedimentology of these plugs once they have fully disconnected from the abandoned bend, fewer studies have detailed the sedimentological processes occurring during the early stages following cutoff initiation. Furthermore, recent studies have highlighted the importance that planform geometry plays in the evolution of neck cutoffs. This study examines the spatial depositional patterns of two neck cutoffs on the White River in central Arkansas, USA, that remain hydrologically connected to the main channel, providing a unique opportunity to research sedimentological processes before disconnection of the abandoned bend. Sediment cores were collected in key locations of each cutoff, including the entrance and exit of the abandoned bends, abandoned bend apices, and newly developed cutoff bars in the downstream channel. The cores were logged and interpreted and grain‐size analyses were performed. In addition to sediment cores, repeat high‐resolution multibeam echo sounding surveys were conducted roughly four hours apart to estimate bedload transport rates and patterns of bedload routing through each cutoff. Results from this research are different from previous studies. Sediment core results show a pattern of deposition typically associated with lower diversion angle chute cutoffs instead of higher diversion angle neck cutoffs. Previous research has indicated that plugging of abandoned bends drives disconnection from the active channel; however, this research shows that disconnection is more associated with the prevention of sediment from being delivered to the abandoned bends due to flow being pulled away from the abandoned bends and the evolving channel morphology.

Rapid adaptive radiation in a hillstream cyprinid fish in the East African White Nile River basin.

Adaptive radiation of freshwater fishes was long thought to be possible only in lacustrine environments. Recently, several studies have shown that riverine and stream environments also provide the ecological opportunity for adaptive radiation. In this study, we report on a riverine adaptive radiation of six ecomorphs of cyprinid hillstream fishes of the genus Garra in a river located in the Ethiopian Highlands in East Africa. Garra are predominantly highly specialized algae-scrapers with a wide distribution ranging from Southeast Asia to West Africa. However, adaptive phenotypic diversification in mouth type, sucking disc morphology, gut length and body shape have probably been found among these ecomorphs in a single Ethiopian river. Moreover, we found two novel phenotypes of Garra ("thick-lipped" and "predatory") that had not been discovered before in this species-rich genus (>160species). Mitochondrial and genome-wide data suggest monophyletic, intrabasin evolution of Garra phenotypic diversity with signatures of gene flow from other local populations. Although sympatric ecomorphs are genetically distinct and can be considered to being young species as suggested by genome-wide single nucleotide polymorphism data, mitochondrial DNA was unable to identify any genetic structure suggesting recent and rapid speciation events. Some data suggest a hybrid origin of the novel "thick-lipped" ecomorph. Here we highlight how, driven by ecological opportunity, an ancestral trophically highly specialized lineage is likely to have rapidly radiated in a riverine environment promoted by the evolution of novel feeding strategies.

Regeneration trends along climate gradients in Taxodium distichum forests of the southeastern United States

The development of relict vegetation at the edges of some ecosystems has taken place particularly in environments where the regeneration of foundational species is declining. As an important stage of regeneration in the Taxodium distichum, this study explored the relationship of cone volume and seed number across environmental gradients in the Mississippi River Alluvial Valley (MRAV) and northern Gulf of Mexico Coast (GOM) in a long-term network of forested wetlands (North American Baldcypress Swamp Network (NABCSN)) from 2007 to 2019. Resembling spheroids, the volumes of Taxodium distichum cones were based on the measured dimensions of the cones collected in swamps across southeastern environmental gradients. Cones with larger volumes also had larger numbers of seeds (r2 = 0.423, F = 113.9, p < 0.0001; Linear regression equation: Seed number per cone = 9.8925223 + 0.8854056* Cone volume cm3). Mean cone volumes were related to water availability with highest volumes in locations with moderate amounts of total annual precipitation (e.g., White River National Wildlife Refuge (NWR) Arkansas, Tensas NWR Louisiana, and Morgan Brake NWR Mississippi), and longer periods of annual percent time of site drawdown. Cone volume was high in 2018 following the 2017 mega-flood in the Mississippi River Alluvial Valley (MRAV) generated by Hurricane Harvey. Mean annual air temperature was not related to cone volume. Along the Gulf Coast, mean cone volume increased from east to west from Florida to Texas. Especially near the edge of the range of T. distichum forests, smaller cones may be related to regeneration failure and lower seed numbers to support regeneration. A better understanding of regeneration constraints can inform managers of the emergence of relict status in these forests.

Parasites of Western Creek Chubsucker Erimyzon claviformis (Cypriniformes: Catostomidae) from Arkansas and Oklahoma, U.S.A.

Between April 2011 and November 2020, 175 individuals of western creek chubsucker Erimyzon claviformis (Girard) (Cypriniformes: Catostomidae) were collected and examined for parasites from 12 sites in the Ouachita, Red, St. Francis, and White river drainages in Arkansas (n = 138 individuals for endoparasites, 22 of same individuals for gill parasites) and from 4 sites in the Red River drainage in Oklahoma (n = 37 individuals for endoparasites, 14 of same individuals for gill parasites). Ninety-nine (57%) were infected with at least 1 parasite, including 2 (6%) of 36 with Piscinoodinium limneticum, 8 (22%) of 36 with 3 different Myxobolus spp., 4 (11%) of 36 with Octomacrum lanceatum, 40 (23%) of 175 with Plagioporus sinitsini, 30 (17%) of 175 with Lissorchis amniculensis, 38 (21%) of 175 with Calientiella etnieri, 3 (2%) of 175 with Isoglaridacris cf. agminis, 10 (6%) of 175 with larval Spiroxys sp., and 1 (0.6%) of 175 with a Neoechinorhynchus sp.; 31 individuals harbored multiple infections. We document several new host and distributional records. Moreover, this report represents only the second published report of the caryophyllid tapeworm C. etnieri since its description more than 46 yr ago.

Intra-and inter-specific competition effects on survival and growth of juvenile Procambarus acutus acutus and Procambarus clarkii

Four similar sizes eastern white river crayfish (Procambarus acutus acutus) and red swamp crayfish (Procambarus clarkii) were stocked separately to determine intra and inter-specific-competition. Three treatment levels were used three treatment levels, with six replicates tanks each with stand green rice (representing a stocking density of approximately 21 individuals per m2). This study was carried out during 90 days to determine growth and survival rate. Results showed that the growth of P. acutus acutus in the interspecific treatment tank was found higher than those grown in the intraspecific-treatment tanks. For P. clarkii, no significant differences in growth (estimated from the mean Total length, TL) were detected between treatments. The survival of the two species was the same up to the first 60 days of the experiment, while the difference in survival was only noticeable at 90 days. The survival rate of P. clarkii in the intraspecific-treatment tanks (55.0%) was higher than in the interspecific tanks (26.7%) treatment, while the survival of P. acutus acutus was found similar in two treatments. It was achieved higher survival, faster growth and larger size in P. a. acutus than P. clarkii when grown in the tank study. Size of body was important in determining competitive interactions between the two species.