Search

Climate change is expected to cause the extinction of vulnerable species and reduce available habitat for others. Freshwater fishes are particularly vulnerable considering they are confined to habitats that are disjunct or prone to fragmentation on the landscape. The alligator gar (Atractosteus spatula) is a species that relies on specific habitat conditions, including water temperature ranges from 20 to 30 °C and flooded vegetation, for successful spawning and recruitment and is likely to be impacted by changes in climate. We created a species distribution model to provide insight about the projected range for alligator gar in the USA under four different climate change outcomes. Our models suggest that the most suitable habitat will change from where alligator gar currently dwell and shift northward and slightly east by 2080. Under the most severe climate scenario, the centroid for the alligator gar range is projected to shift to the north-northeast, nearly 900 km from the current location in central Louisiana, to south-central Illinois. Freshwater fish have limited dispersal capabilities, and alligator gar will likely be unable to populate newly suitable habitats without translocations by fishery managers. Suitable habitat is projected to decline across alligator gar's current range, and it is plausible that extirpation will occur regionally. However, the initial impacts of decreasing suitability may be overlooked, considering that alligator gar are a long-lived species and larger, more mature individuals will likely persist through the end of their life span across the current range even as suitable habitat decreases. [ABSTRACT FROM AUTHOR]

Informed management and conservation efforts are vital to sustainable recreational fishing and biodiversity conservation. Because the taxonomic rank of species is important in conservation and management strategies, success of these efforts depends on accurate species delimitation. The Black Basses (Micropterus) are an iconic lineage of freshwater fishes that include some of the world's most popular species for recreational fishing and world's most invasive species. Despite their popularity, previous studies to delimit species and lineages in Micropterus suffer from insufficient geographic coverage and uninformative molecular markers. Our phylogenomic analyses of ddRAD data result in the delimitation of 19 species of Micropterus, which includes 14 described species, the undescribed but well-known Altamaha, Bartram's, and Choctaw basses, and two additional undescribed species currently classified as Smallmouth Bass (M. dolomieu). We provide a revised delimitation of species in the Largemouth Bass complex that necessitates a change in scientific nomenclature: Micropterus salmoides is retained for the Florida Bass and Micropterus nigricans is elevated from synonymy for the Largemouth Bass. The new understanding of diversity, distribution, and systematics of Black Basses will serve as important basis for the management and conservation of this charismatic and economically important clade of fishes. [ABSTRACT FROM AUTHOR]

Purpose: 99mTc-tricarbonyl-nitrilotriacetic acid, [99mTc]Tc(CO)3(NTA), is a new 99mTc-renal radiopharmaceutical with a clearance equal to that of 131I-ortho-iodohippuran, [131I]I-OIH. Our purpose was to compare the performance of [99mTc]Tc(CO)3(NTA) and [99mTc]Tc-MAG3 in patients with suspected obstruction. Methods: [99mTc]Tc(CO)3(NTA) was prepared with commercially available NTA ligand and CRS Isolink kit, and isolated by HPLC. Eighteen adult patients referred for diuretic renography received an intravenous injection of approximately 40 mg of furosemide 15 min prior to either [99mTc]Tc(CO)3(NTA) or [99mTc]Tc-MAG3 (mean activity of 47 ± 4.4 MBq). Data were acquired for 24 min followed by an anterior image of the liver and gall bladder and a measure of voided volume. Patients received a second furosemide injection equal to one third of the original dose followed fifteen minutes later by administration of the alternate tracer, mean activity of 320 ± 34 MBq. Clearances were measured using a camera-based technique. Results: The clearance of NTA was greater than that of MAG3, 331 ± 146 versus 271 ± 105 mL/min/1.73 m2, respectively, p < 0.0001. The kidney to background ratio for NTA was greater than that of MAG3 for both left and right kidneys, p < 0.001; the 20 min/maximum count ratio was significantly less, p < 0.0001. There was no significant difference in the voiding volumes following NTA and MAG3 administration, 598 ± 237 mL versus 498 ± 170 mL, respectively, p = 0.07. Gall bladder activity was not observed with NTA but was present in 6/17 MAG3 studies. Images and renogram curves were comparable except for two patients where the NTA study excluded obstruction but the MAG3 study suggested an indeterminate or obstructed kidney. Conclusions: Unlike MAG3, NTA is not eliminated via the hepatobiliary track. Moreover, NTA has a higher kidney to background ratio and more rapid clearance than MAG3. These advantages should allow more robust camera-based clearance measurements and may lead to better discrimination between obstructed and non-obstructed kidneys. [ABSTRACT FROM AUTHOR]

The Smallmouth Bass (Micropterus dolomieu; SMB) is a widely distributed black bass species, but the southwestern edge of the species range within the Interior Highlands contains some of the most divergent ecotypes. The Neosho subspecies (M. d. velox) inhabits tributaries of the Arkansas River within the Ozark Mountains and a second lineage is reported from drainages of the Ouachita Mountains. We sought to develop a single nucleotide polymorphism (SNP) panel to (1) diagnose hybridization with sympatric Spotted Bass (Micropterus punctulatus; SPB) and non-native Northern SMB (M. d. dolomieu) stocked in the region, and (2) delineate population structure within the ranges of the Neosho and Ouachita SMB lineages. We obtained 76 individual SMB samples from across their range but concentrated within the Interior Highlands (n = 50). We also included 3 SPB to allow for hybrid detection and 3 Shoal Bass (Micropterus cataractae) as an outgroup. Phylogenetic trees constructed with the generated SNP data corroborated the existence of at least three major lineages of SMB (Northern, Neosho, and Ouachita), each containing varying degrees of differentiation among major drainages. Simulation analyses revealed that chosen SNPs had high power (> 0.9) to assign SMB × SPB hybrid categories and similarly high power (> 0.8) for Northern SMB × Interior Highlands SMB hybrids. Clustering methods delineated major inter-basin population structure within the native ranges of Neosho and Ouachita SMB with chosen SNPs. Anticipated uses of the resulting 192-loci SNP panel include conservation planning, fisheries management assessments, and ecological investigations of the Neosho and Ouachita SMB lineages. [ABSTRACT FROM AUTHOR]

Cryptic invasive species are particularly problematic to study, manage, and control because of the difficulty detecting these species within their invaded habitats. Such is the case of the Asian Swamp Eel (Monopterus albus; ASE) where it is established in vegetated marshes along the Chattahoochee River, Georgia. Adult eels have been nearly impossible to detect or quantify with traditional sampling, although leaf-litter trapping of juvenile ASEs has been somewhat successful. In this study, we leveraged a collection of juveniles from the 2015 cohort and used single-nucleotide polymorphisms to reconstruct sibship among these juveniles in COLONY. Sibship reconstruction allowed us to learn about adult breeding behaviors and provided the first quantified estimates of breeder abundance. Pedigree reconstruction revealed that adults of both sexes were polygamous and likely traveled up to 0.5 km among marsh habitats during a single breeding season. Estimates of the number of breeding adults contributing to offspring (Ns) and the effective number of breeders (Nb) indicated an approximate minimum bound of 100 breeding adults in the marshes in 2015. Our study updated the invasion status of a cryptic population formerly riddled with uncertainty, highlighting that low captures of adult eels in the study area have been the result of low detectability, not low abundance. Given that low detectability would likely hinder removal efforts, our results suggest that future efforts could focus on suppression of ASE abundance when they are most vulnerable to capture and containing the spatial extent of the invasion. [ABSTRACT FROM AUTHOR]

Due to geologic processes and recent anthropogenic introductions, patterns of genetic and morphological diversity within the Smallmouth Bass (Micropterus dolomieu), which are endemic to the central and eastern United States (USA), are poorly understood. We assessed genetic and morphological differentiation between the widespread Northern Smallmouth Bass (M. d. dolomieu) and the more restricted Neosho Smallmouth Bass (M. d. velox) where their ranges meet in the Central Interior Highlands ecoregion (CIH). Data from 14 microsatellite loci were used to conduct Structure and principal components analyses to evaluate diversity across populations and screen for hybridization with sympatric Spotted Bass (M. punctulatus). We also tested for morphological differences using five morphometric traits and one meristic trait. We found support for three genetic clusters corresponding to previously described taxonomic variation; five clusters largely corresponding to river systems; and nine clusters representing hierarchical population structure within both ranges. We found evidence of a unique genetic cluster in tributaries of the White River within the Northern Smallmouth Bass range and admixture between the subspecies throughout the Neosho range. We also found evidence of morphological differentiation between subspecies; Neosho Smallmouth Bass exhibited larger head length than Northern Smallmouth Bass relative to total length, and there was a significant interaction of subspecies and orbital length, possibly indicating differential growth patterns between subspecies. Our results reveal multiple levels of divergence, suggesting the CIH harbors greater and more complex Smallmouth Bass diversity than previously thought. [ABSTRACT FROM AUTHOR]

In the original publication of the article, Table 2 was published incorrectly. The correct Table 2 is given in this Correction. [ABSTRACT FROM AUTHOR]