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Brian Balmer, Eric Zolman, Jennie Bolton, Deborah Fauquier, Erin Fougeres, R. Clay George, Tracey Goldstein, Michael Gowen, Trip Kolkmeyer, Carolina Le-Bert, Blair Mase, Terry Norton, Jon Peterson, Teri Rowles, Jerry Saliki, Gina Ylitalo
Tursiops truncatus (Common Bottlenose Dolphin) in Georgia are exposed to multiple natural and anthropogenic stressors. Here, we describe a case study of an adult, male Common Bottlenose Dolphin entangled in marine debris, that was temporarily captured, disentangled, sampled for health assessment, satellite tagged, and released. Photographic-identification history and short-term tagging data support that the animal, Z58, has long-term site fidelity to the estuaries of southern Georgia. Health-assessment results identified several abnormal health parameters, including anemia, which likely resulted from exposure to extremely high site-specific contaminants that are known in the area. This note provides a case study of the various stressors to which Common Bottlenose Dolphins in Georgia are exposed, which can be used to develop effective management strategies for at-risk populations.
Native warm-season grasses (NWSG) are gaining merit as biofuel feedstocks for ethanol production with potential for concomitant production of cattle forage and wildlife habitat provision. However, uncertainty continues regarding optimal production approaches for biofuel yield and forage quality within landscapes of competing wildlife conservation objectives. We used a randomized complete block design of 4 treatments to compare vegetation structure, forage and biomass nutrients, and biomass yield between Panicum virgatum (Switchgrass) monocultures and NWSG polycultures harvested once or multiple times near West Point, MS, 2011–2013. Despite taller vegetation and greater biomass in Switchgrass monocultures, NWSG polycultures had greater vegetation structure heterogeneity and plant diversity that could benefit wildlife. However, nutritional content from harvest timings optimal for wildlife conservation (i.e., late dormant season-collected biomass and mid-summer hay samples) demonstrated greater support for biofuel production than quality cattle forage. Future research should consider testing various seed mixes for maximizing biofuel or forage production among multiple site conditions with parallel observations of wildlife use.
Genetic diversity at the Major Histocompatibility Complex (MHC) is particularly important for species viability as it allows populations to respond to emerging pathogens and infectious disease. Patterns of variation at this gene complex serve as a useful complement to information obtained from neutral loci for planning management and conservation strategies that seek to ensure the adaptive potential of at-risk species. In this study, we investigated patterns of genetic variation at exon 2 of the MHC class II gene in the critically endangered Fundulus julisia (Barrens Topminnow). This species has undergone dramatic declines over the last 30 years, leading to its recent proposal for federal protection under the Endangered Species Act. Patterns of nucleotide substitution and phylogenetic analyses revealing trans-species polymorphisms suggest that this locus has been of adaptive importance in the history of this species. Despite recent population declines and documented population bottlenecks, measures of genetic diversity were high in comparison to patterns observed at putatively neutral microsatellite and mitochondrial markers. Results from this study are discussed in the context of recovery plans for the Barrens Topminnow and lend support to the previous designation of evolutionary significant units and management units based on neutral markers.
As part of the US government's Foreign Game Investigation Program (FGIP), there was an extensive and sustained effort in the 1960s to introduce Gallus gallus (Red Junglefowl) in the southeastern United States. We review the history of this effort with the objective of showing how well-documented introductions such as those carried out by FGIP can shed light on current research questions. The stock for the junglefowl introductions was captured in northern India under the direction of Gardiner Bump in areas thought to be free of hybridization with domestic Gallus gallus domesticus (Chicken). A total of 117 wild-caught birds was shipped to the United States as breeding stock, and over a 10-year period nearly 10,000 Red Junglefowl were introduced into at least 52 sites in 8 states. Despite this massive effort, no wild populations of Red Junglefowl have persisted in the Southeast. However, descendants of the FGIP junglefowl still exist in captivity. Careful breeding of birds from the original FGIP has resulted in a captive population of 100–200 Red Junglefowl distributed among several aviculturists in the Southeast and thought to be derived from populations that predate introgression with domestic Chickens. Because of their well-documented origins, these descendants of FGIP junglefowl are probably the genetically purest captive population of this species, and they have a tremendous research legacy for the conservation of Red Junglefowl and study of the genetic changes associated with domestication.
Anas fulvigula (Mottled Duck) has experienced long-term population declines due to habitat loss and other anthropogenic factors. Our objectives were to (1) generate annual survival and recovery estimates, while examining the influence of age and sex, and (2) examine the influence of rainfall and drought on reproductive success. We followed the Brownie approach using the RMark package in R to analyze 4967 bandings and 705 recoveries from 2004–2015. We examined linear and curvilinear relationships between precipitation variables and a reproductive index. Hatch-year (HY) males had the highest annual recovery probability, while after-hatch-year (AHY) females had the lowest. Annual survival varied predominately by sex but also with age. Hatch-year females had the lowest estimate of survival, while after-hatch-year males had the highest. Total rainfall during peak nesting season showed a weak negative relationship with our reproductive success index (β = -0.0085, 95% CI: -0.0240, 0.0070), and was our only competitive model besides the null. Annual survival and recovery estimates were similar to other studies on Mottled Ducks. Our reproductive success analysis was inconclusive in that either there is no effect of precipitation or the measures we used for the reproduction index or the predictor variables were inadequate.
High harvest rates during the 1900s led to declines of Macrochelys temminckii (Alligator Snapping Turtle) throughout much of its range. Recent research to determine the status of Alligator Snapping Turtles has been completed in some regions of Louisiana, but information is lacking for the southwestern region of the state. To determine the distribution and abundance of Alligator Snapping Turtles in southwestern Louisiana, we conducted trapping efforts in the lower Calcasieu, Mermentau, and lower Sabine river systems from March 2012 through October 2013 using baited hoop nets. In 731 trap nights, we captured 14 individuals (2 M, 4 F, 8 Juv) in the Mermentau and Calcasieu river systems. Our trapping efforts did not detect Alligator Snapping Turtles at Sabine River sites, although one individual was found dead on a fishing hook of a hanging limb line. Our catch per unit effort (CPUE) was 0.021 across the 3 river drainages. Population levels appear to be smaller than observed elsewhere in Louisiana and in neighboring southern states. We recommend that future surveys be conducted to determine population trajectories and that a system be implemented for monitoring commercial fishing bycatch and recreational harvest.
Temperature impacts organisms at a finer scale than that represented by weather stations and climate models. I investigated whether the expansion of a non-native herbaceous plant species, Tradescantia fluminensis (Small-leaf Spiderwort), up the slopes of the Apalachicola River, FL, was related to topography and/or surface temperature. These slopes comprise the remaining range of Torreya taxifolia (Florida Torreya), one of the rarest tree species in North America, and reports raise the concern that the development of dense patches of Small-leaf Spiderwort can inhibit the establishment of native plants and tree seedlings. I measured vegetative growth over 1 year and surface-temperature minima during the winter of 2016–2017 at the upland boundaries of Small-leaf Spiderwort patches. Temperatures were colder at higher elevations and greater distances from the floodplain, but did not reach the lethal temperature of -4.2 °C. Ninety four percent of patches survived. They expanded upslope an average of 1.2 m/y, and could reach the closest Florida Torreya trees in 2 y. Temperature minima were >1.3 °C warmer than those at the weather station in nearby Wilma, FL. Historical records for Wilma indicate that two-thirds of winters reach sufficiently cold temperatures to kill Small-leaf Spiderwort, and cold temperatures in January 2018 did kill a small proportion of plants. The lack of sufficiently cold temperature since 2011 might account for the recent expansion of Small-leaf Spiderwort in the Apalachicola floodplain.
Knowledge of tree-growth response to extreme climatic events, such as drought, is useful for forest managers to model the effects of future disturbances, and to develop management plans that mitigate the detrimental impacts. We analyzed the effects of an exceptional drought on Pinus palustris (Longleaf Pine) radial growth in the Alabama Fall Line Hills, based on site conditions and tree age. Results indicated that radial-growth response to drought was not influenced by site condition as we initially hypothesized, but was influenced by tree age. Management for resiliency to disturbance in Longleaf Pine ecosystems should consider the complexity of individual tree-growth response as a function of age and growing conditions.
Hypophthalmichthys molitrix (Silver Carp) are invasive and abundant in the Mississippi River system, where they consume phytoplankton. There is concern that Silver Carp may influence phytoplankton community structure with cascading effects on other trophic levels. Information is needed regarding Silver Carp phytoplankton-consumption rates and prey selection to assess their potential impact on the food-web in the river. We investigated Silver Carp diets in a backwater lake of the Lower Mississippi River in order to quantify phytoplankton prey selectivity. We made measurements on 4 dates over a 2-y period, which spanned a range of hydrologic connectivity between the lake and the river and a variety of fish sizes. We quantified selection by comparing phytoplankton community composition in the lake to prey in foreguts of captured Silver Carp using Vanderploeg and Scavia's (1979) relativized selection index. With a possible exception of diatoms on 1 date, there was no relationship of sample date or fish size on prey selection. However, there was a consistent pattern in prey selection: euglenoid algae were positively selected, selection of colonial algae and diatoms was variable, and flagellates and filamentous cyanobacteria were negatively selected. Results are discussed in the context of a conceptual model for Silver Carp phytoplanktivory that incorporates the roles of habitat selection, prey availability, prey capture and processing, and digestive physiology.
As a non-invasive approach for sampling small mammals, track tubes may be especially useful in species occupancy studies that do not require marking of individuals. However, such studies may involve significant uncertainty in identifying many tracks to species. Using 37 study sites in eastern Alabama and Tennessee, we compared relative differences in detection probabilities with track tubes vs. live traps for Peromyscus (deermice), Oryzomys palustris (Marsh Rice Rat), and Sigmodon hispidus (Hispid Cotton Rat). In analyses that ignored identification uncertainty or that used false-positive occupancy models to address this uncertainty, track tubes and live traps had similar detection probabilities. When uncertain detections were omitted from analysis, effective detectability was lower with track tubes. False-positive occupancy modeling indicated that track-identification uncertainty could not be ignored, as there was a non-zero probability of false-positive detections. False-positive occupancy designs have high relevance to track-tube studies; in addition, such studies should ensure that track identification is done under the oversight of an experienced tracker.
We evaluated whether geographic distance and soil characteristics influence genetic structure of nitrogen-fixing bacterial symbionts associated with the host plant Chamaecrista fasciculata (Partridge Pea). We tested phylogeographic clustering and associations between genetic distance, geographic distance, and soil variables using sequences of 2 bacterial genes and soil chemistry across 23 sites in Mississippi. We identified rhizobia isolated from Partridge Pea as Bradyrhizobium. We detected significant genetic structure at a regional level, and determined that rhizobia within each region were more phylogenetically related than expected. Significant correlation between genetic distance and distances based on soil chemistry suggests environmental influences on rhizobia diversity. High levels of diversity among rhizobia over small spatial scales suggest that symbionts respond to local factors. Understanding geographic diversity in natural assemblages of rhizobia aids in predicting how hosts and symbionts respond to environmental perturbations.
Spilogale putorius (Eastern Spotted Skunk) is a nocturnal small carnivore that uses sites within cover for resting, raising of young, and protection from predators and inclement weather. We examined activity patterns of male radio-collared Eastern Spotted Skunks in Alabama by placing game cameras at resting-site entrances during winter and spring. Monitored skunks were strictly nocturnal and were never active before sunset or after sunrise. Ambient temperature and moon illumination influenced skunk activity, with greater aboveground activity occurring at greater ambient temperatures and lower moon illumination. Lower ambient temperatures may decrease skunk activity due to greater thermoregulatory costs and less prey availability. Skunks may reduce aboveground activity during times of greater moon illumination due to increased vulnerability to predation.
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