Disturbance, dispersal and marine assemblage structure: A case study from the nearshore Southern Ocean

Disturbance is a key factor in most natural environments and, globally, disturbance regimes are changing, driven by increased anthropogenic influences, including climate change. There is, however, still a lack of understanding about how disturbance interacts with species dispersal capacity to shape marine assemblage structure. We examined the impact of ice scour disturbance history (2009–2016) on the nearshore seafloor in a highly disturbed region of the Western Antarctic Peninsula by contrasting the response of two groups with different dispersal capacities: one consisting of high-dispersal species (mobile with pelagic larvae) and one of low-dispersal species (sessile with benthic larvae). Piecewise Structural Equation Models were constructed to test multi-factorial predictions of the underlying mechanisms, based on hypothesised responses to disturbance for the two groups. At least two or three disturbance factors, acting at different spatial scales, drove assemblage composition. A comparison between both high- and low-dispersal models demonstrated that these mechanisms are dispersal dependent. Disturbance should not be treated as a single metric, but should incorporate remote and direct disturbance events with consideration of taxa-dispersal and disturbance legacy. These modelling approaches can provide insights into how disturbance shapes assemblages in other disturbance regimes, such as fire-prone forests and trawl fisheries

A County-Based Northern Bobwhite Habitat Prioritization Model for Kentucky

Planning the management of northern bobwhite (Colinus virginianus) habitat at a statewide-scale is daunting. Native grassland restoration is difficult to manage in Kentucky because . 99% of the Commonwealth’s original grassland area has been lost to agriculture, succession, and development. We created a county prioritization model designed to target areas of grasslands and landowners likely to participate in conservation programs. Our goal was to identify 10% of the state as high priority for bobwhite habitat restoration. We created an east and west model divided by the Appalachian Mountains. The west model was designed to target production-oriented operators farming marginal lands, whereas the east model targeted reclaimed minelands. We used agricultural, landcover, and staff data to build county prioritization models in 2006 and 2011. The models targeted 16.6% and 17.6% of the state in 2006 and 2011, respectively. However, if areas of large, contiguous blocks of forests were excluded, the area total was much closer to 10%. Fifty percent of the high priority counties changed in the west model, and 33% of the counties in the east model changed over 5 years. Implementing a county prioritization model in conjunction with a finer-scale, biological targeted approach could focus conservation efforts with greater potential for success, but the models should be reconstructed at 5- to 10-year intervals to account for changes in conservation delivery potential. A modification of our technique may serve to validate or as an alternative to improve National Bobwhite Conservation Initiative 2.0

Results from Kentucky’s 10-year Bobwhite Recovery Plan

The northern bobwhite (Colinus virginianus; hereafter, bobwhite) has experienced a precipitous population decline through almost all its historical range over the last 6 decades. We initiated a 10-year restoration plan in Kentucky, USA in 2008 and reported on it through 3 published “Road to Recovery” reports along with 30 peer-reviewed articles and abstracts, 2 technical documents, 7 theses or dissertations, and 11 popular literature pieces. Seven Quail Focus Areas were selected across the state based on site personnel, geographic position (east to west), and land ownership (e.g., private, public, state, federal) for monitoring and habitat management. The focus areas averaged 11,895 acres and area managed for quail on an annual basis ranged from 9% to 42%. Management took the form of herbicide applications, disking, fire, planting, grazing, control of woody vegetation, and mowing. Hierarchical distance sampling models using time-of-removal information to inform detection processes were used to assess bobwhite density on each focus area. Models were based on spring breeding bird point counts in which a suite of grassland songbirds were recorded and fall covey counts in which only bobwhite were recorded. Roadside surveys (direct observation) and hunter harvest information were also used for statewide comparisons of focus areas and statewide trends. Across all years and focus areas a 40% increase in the quail population was observed in 20 years (38%) of the possible 53 years of survey data. Stable to increasing trends were also observed in focal area populations of dickcissel (Spiza americana), eastern meadowlark (Sturnella magna), eastern kingbird (Tyrannus tyrannus), field sparrow (Spizella pusilla), prairie warbler (Setophaga discolor), and Bell’s vireo (Vireo bellii). A focus on habitat management and associated monitoring on relatively small (\u3c20,000 acres) areas was shown to be successful on an individual area, as determined by increases in bird numbers across years and challenges completed in the Quail Plan but did not result in an observed increase in statewide quail indices. Future quail restoration plans in Kentucky should be directed more toward open production land, which is made up of 6 million acres of pastureland, hay land, row crop agriculture, reverting fields, reclaimed mineland, and grasslands. This work will be completed by utilizing working lands, such as field borders in row crop systems and grazing native warm-season grasses in pasture or hay systems, for wildlife activities. Monitoring systems on these production lands will be in the breeding season only and autonomous recording devices will be used in lieu of human observers to cover the greater area of open landscape

A Physiologically Based Model of Orexinergic Stabilization of Sleep and Wake

The orexinergic neurons of the lateral hypothalamus (Orx) are essential for regulating sleep-wake dynamics, and their loss causes narcolepsy, a disorder characterized by severe instability of sleep and wake states. However, the mechanisms through which Orx stabilize sleep and wake are not well understood. In this work, an explanation of the stabilizing effects of Orx is presented using a quantitative model of important physiological connections between Orx and the sleep-wake switch. In addition to Orx and the sleep-wake switch, which is composed of mutually inhibitory wake-active monoaminergic neurons in brainstem and hypothalamus (MA) and the sleep-active ventrolateral preoptic neurons of the hypothalamus (VLPO), the model also includes the circadian and homeostatic sleep drives. It is shown that Orx stabilizes prolonged waking episodes via its excitatory input to MA and by relaying a circadian input to MA, thus sustaining MA firing activity during the circadian day. During sleep, both Orx and MA are inhibited by the VLPO, and the subsequent reduction in Orx input to the MA indirectly stabilizes sustained sleep episodes. Simulating a loss of Orx, the model produces dynamics resembling narcolepsy, including frequent transitions between states, reduced waking arousal levels, and a normal daily amount of total sleep. The model predicts a change in sleep timing with differences in orexin levels, with higher orexin levels delaying the normal sleep episode, suggesting that individual differences in Orx signaling may contribute to chronotype. Dynamics resembling sleep inertia also emerge from the model as a gradual sleep-to-wake transition on a timescale that varies with that of Orx dynamics. The quantitative, physiologically based model developed in this work thus provides a new explanation of how Orx stabilizes prolonged episodes of sleep and wake, and makes a range of experimentally testable predictions, including a role for Orx in chronotype and sleep inertia

Hunter Harvest of Pen-Reared Northern Bobwhites Released From the Surrogator

There has been increased interest in releasing pen-reared northern bobwhites (Colinus virginianus) to meet quail hunting and shooting objectives as populations have declined. The Surrogatort is a commercially available product for rearing and releasing gamebirds into the wild and is promoted as a method to enhance bobwhite survival, improve hunting, and increase recruitment from natural reproduction. We used return-to-hunter bag data from 3 properties in Alabama, Georgia, and Kentucky to evaluate the Surrogatort as a pre-hunting season release technique for pen-reared bobwhites. Across all sites, 3,859 5-week old banded bobwhite chicks were released at varying times during June through October, 2005–2010. Ninety-three quail hunts were conducted during November through January 2005–2011 comprising 431 hunt party hours which resulted in 19 banded bobwhites being harvested. The return-to-hunter bag for all sites combined was 0.005 (range 1⁄4 0.000 to 0.008). This was considered unsatisfactory at each site and across all sites combined for a quality hunting/shooting experience. The mean cost per chick released was $3.41 (range 1⁄4$2.74 to $3.88) including the costs of quail chicks, Surrogatort units, propane, and feed across all sites. The mean cost per bird returned-to-hunter bag (Alabama and Georgia) was$655.80 (range 1⁄4 $489.91 to$821.68). These costs did not include economic depreciation of Surrogatort units

Evaluating Hunting Success of Pen-Reared and Wild Northern Bobwhite in a Reclaimed Kentucky Mineland

Northern bobwhites (Colinus virginianus) have experienced severe population declines across their distribution. In order to address population declines and to continue providing hunting opportunities, multi-state efforts have been undertaken to stabilize and restore bobwhite populations. Ongoing efforts using the National Bobwhite Conservation Initiative’s quail focus area approach have so far demonstrated success throughout Kentucky. However, population increases in the Peabody Bobwhite Focal Area, in western Kentucky, have not been correlated to increases in perceived hunter success. Consequently, some sportsmen question the effectiveness of focal area conservation. In response to hunter concerns, we tested dog hunting ability with wild and pen-reared bobwhites. We also measured evasive behaviors of wild bobwhite using radiotelemetry. During the 2013–2014 and 2014–2015 hunting seasons we conducted 114 dog trials. Dogs detected bobwhite during 46 of 59 (78.0%) pen-reared trials and 16 of 55 (29.1%) wild bird trials. When dogs did not detect wild quail, birds ran away 64.1% of the time and remained motionless 20.5% of the time. Using an information-theoretic approach, we determined that bird type (wild vs. pen-reared) had a significant effect on bird detection, with dogs 8.62 times more likely to detect pen-reared birds than wild birds. We recommend that hunters be informed about differences in dog detection rates between pen-reared and wild bobwhite so that public support needed for wild bobwhite restoration can persist

Coarse-Grained Models of Biological Membranes within the Single Chain Mean Field Theory

The Single Chain Mean Field theory is used to simulate the equilibrium structure of phospholipid membranes at the molecular level. Three levels of coarse-graining of DMPC phospholipid surfactants are present: the detailed 44-beads double tails model, the 10-beads double tails model and the minimal 3-beads model. We show that all three models are able to reproduce the essential equilibrium properties of the phospholipid bilayer, while the simplest 3-beads model is the fastest model which can describe adequately the thickness of the layer, the area per lipid and the rigidity of the membrane. The accuracy of the method in description of equilibrium structures of membranes compete with Monte Carlo simulations while the speed of computation and the mean field nature of the approach allows for straightforward applications to systems with great complexity.Comment: Accepted for publication in Soft Matte

Chagas disease in a domestic transmission cycle in southern Texas, USA

Centers for Disease control and Prevention http://www.cdc.gov/ncidod/EID/vol9no1/02-0217.htmAfter three dogs died from acute Chagas cardiomyopathy at one location, an investigation was conducted of the home, garage, and grounds of the owner. A serologic study was conducted on stray dogs, and an ecologic niche model was developed to predict areas where the vector Triatoma gerstaeckeri might be expected