Nocturnal Period Research Articles

Diel regulation of photosynthetic activity in the oceanic unicellular diazotrophic cyanobacterium Crocosphaera watsonii WH8501.

The oceanic unicellular diazotrophic cyanobacterium Crocosphaera watsonii WH8501 exhibits large diel changes in abundance of both Photosystem II (PSII) and Photosystem I (PSI). To understand the mechanisms underlying these dynamics, we assessed photosynthetic parameters, photosystem abundance and composition, and chlorophyll-protein biosynthesis over a diel cycle. Our data show that the decline in PSII activity and abundance observed during the dark period was related to a light-induced modification of PSII, which, in combination with the suppressed synthesis of membrane proteins, resulted in monomerization and gradual disassembly of a large portion of PSII core complexes. In the remaining population of assembled PSII monomeric complexes, we detected the non-functional version of the D1 protein, rD1, which was absent in PSII during the light phase. During the dark period, we also observed a significant decoupling of phycobilisomes from PSII and a decline in the chlorophyll a quota, which matched the complete loss of functional PSIIs and a substantial decrease in PSI abundance. However, the remaining PSI complexes maintained their photochemical activity. Thus, during the nocturnal period of nitrogen fixation C. watsonii operates a suite of regulatory mechanisms for efficient utilization/recycling of cellular resources and protection of the nitrogenase enzyme.

Movements of Feral Hogs in Response to Warfarin Bait Consumption

The distribution of feral hogs throughout North American has increased dramatically since their introduction. The use of toxicants has proven to be a n effective tool in controlling feral hog numbers in several countries. Using data from 13 GPS hogs, we compared movements and space use of control and treated hogs between pre-baiting and baiting phases of 3 feral hog toxicant field tests. Generalized linear mixed models were used to explain prospective changes in movements. In addition, we evaluated the distance of toxicant-killed feral hog carcasses from bait stations, roads, and cultivated crop plots. The mean distances traveled by treatment hogs between the pre-baiting and baiting periods was reduced by 43.9%, 32.1%, and 48.8% for daily, diurnal, and nocturnal periods, respectively. Daily and nocturnal movements exhibited a significant decrease between pre-baiting and baiting phases by feral hogs as a result of bait consumption. Mean space use size between the pre-baiting and baiting periods for treatment hogs was reduced by 37.5% and 30.0% for 95% MCP and 50% MCP, respectively but was not a result of bait consumption. Toxicant-killed feral hog carcass distance from bait stations, cultivated crops, and roads averaged (± SE) 919.4 ± 68.1 m, 908.9 ± 72.1 m, and 120.7 ± 34.9 m, respectively. These carcasses were never recovered from crop plots or near roads and were typically found in natural land cover types. The toxicant warfarin reduced movements of feral hogs, which in turn can reduce their damage to crop and reduce the spread of disease.

Microclimate urban in residential areas in the nocturnal period: Study in Santa Maria, RS

Microclimate urban in residential areas in the nocturnal period: Study in Santa Maria, RS

Recognizing the danger zone: response of female white‐tailed to discrete hunting events

The landscape of fear theory proposes that prey should utilize habitat over space and time such that demographic risk is minimized. White‐tailed deerOdocoileus virginianusrespond to temporally and spatially predictable threats posed by humans consistent with the landscape of fear theory. However, few studies examining the response of deer to hunting have accounted for the localized nature of risk. To determine if white‐tailed deer are able to recognize and respond to risks posed by hunters relative to specific hunting locations, we equipped 38 female white‐tailed deer with GPS collars August–December 2013–2015. Deer were generally found to increase use of feeders, food plots, and vulnerability zones during crepuscular and nocturnal periods as the hunting season progressed. However, deer use of areas around hunting stands decreased during the middle of the day and increased at night in the days immediately following a stand being hunted. We detected no change in use of areas around hunting stands during crepuscular hours in days following when a stand was hunted. Our results suggest that female white‐tailed deer are able to recognize and respond to localized risks and do so with a gradient of responses based on localized risk history. However, response was only apparent when analysis accounted for the localized nature of risk, suggesting previous studies may have underestimated the ability of deer to respond to such threats.

Nocturnal Hypoxia Improves Glucose Disposal, Decreases Mitochondrial Efficiency, and Increases Reactive Oxygen Species in the Muscle and Liver of C57BL/6J Mice Independent of Weight Change.

Although acute exposure to hypoxia can disrupt metabolism, longer-term exposure may normalize glucose homeostasis or even improve glucose disposal in the presence of obesity. We examined the effects of two-week exposure to room air (Air), continuous 10% oxygen (C10%), and 12 hr nocturnal periods of 10% oxygen (N10%) on glucose disposal, insulin responsiveness, and mitochondrial function in lean and obese C57BL/6J mice. Both C10% and N10% improved glucose disposal relative to Air in lean and obese mice without evidence of an increase in insulin responsiveness; however, only the metabolic improvements with N10% exposure occurred in the absence of confounding effects of weight loss. In lean mice, N10% exposure caused a decreased respiratory control ratio (RCR) and increased reactive oxygen species (ROS) production in the mitochondria of the muscle and liver compared to Air-exposed mice. In the absence of hypoxia, obese mice exhibited a decreased RCR in the muscle and increased ROS production in the liver compared to lean mice; however, any additional effects of hypoxia in the presence of obesity were minimal. Our data suggest that the development of mitochondrial inefficiency may contribute to metabolic adaptions to hypoxia, independent of weight, and metabolic adaptations to adiposity, independent of hypoxia.

Factors influencing mercury uptake by leaves of stone pine (Pinus pinea L.) in Almadén (Central Spain).

The use of trees for biomonitoring of mercury (Hg) and other atmospheric pollutants is of increasing importance today. Leaves from different species have been the most widely used plant organ for this purpose, but only pine bark, and not leaves, was used to monitor Hg pollution. In Almadén (South Central Spain), the largest cinnabar (HgS) deposits in the world have been mined for over 2000years to obtain metallic Hg and this activity has caused the widespread dispersion of this toxic element in the local environment. A strip of pine trees, 2750m in length, adjacent and to the South of the mining town has been studied in order to evaluate pine tree needles as monitors for Hg contamination in this heavily polluted area. The study involved the collection of pine tree leaves from several discrete sites along the strip, as well as samples from other nearby locations, together with soil samples and monitoring of atmospheric Hg in the area during both the day and night. Leaves and soils were analyzed for total Hg concentration by means of atomic absorption spectrometry; the leachable fraction of soil Hg was also analyzed by the CV-AFS technique. The results indicate that soils from the investigated area were not directly affected by mining related pollution, with low total Hg levels (3-280mgkg-1) found in comparison with the nearby Almadén metallurgical precinct and very low leachable Hg contents (0.27-59.65mgkg-1) were found. Moreover, pine tree needles have a low uptake capacity, with lower THg levels (0.03-6.68mg kg-1) when compared to those of olive trees in Almadén. However, pine needles do show significant variability with regard to the distance from the source. Gaseous Hg exhibits a similar pattern, with higher levels close to the source, especially during night time (225ngm-3). A multiple linear regression analysis (MLRA) revealed that gaseous Hg in the nocturnal period is the prime factor that influences the amount of Hg uptake by pine tree needles. This finding makes pine needles a promising candidate to biomonitor gaseous Hg on a local or regional scale worldwide. Almadén pine tree needles have been exposed to a number of different Hg sources, including the primary one, namely the old mine dump, and secondary sources such as polluted roads or illegal urban residual waste. The secondary sources cause some minor discrepancies in the model established by the MRLA. The biomonitoring capacity of pine needles needs to be evaluated in areas far from the source. The process involved in gaseous Hg uptake by pine needles appears more likely to involve sorption in the external part of the needle than uptake through stomas, thus making this process strongly dependent on high atmospheric Hg concentrations.

Thermal analysis of greenhouses installed under semi arid climate

The greenhouse design as well as the cover material properties in particular may strongly impact the greenhouse energy. To study the effect of these parameters, three typical unheated greenhouses equipped with rows of canopy were considered. Experiments were launched to establish the boundary conditions and validate the model. Two parametric studies were carried out: for the nocturnal period when the energy performance of each type of greenhouse was investigated, and for the diurnal period, when the sun path was simulated taking into account the type of the cover, its spectral optical and thermal properties. Results indicate that for the nocturnal period, the ambient air temperature in the tunnel and vertical wall greenhouse was relatively homogenous and warmer compared with the temperature distribution in the Venlo greenhouse. The plastic greenhouse, especially the tunnel one had better performances concerning the homogenization of the climate and the thermal energy storage. Concerning the diurnal period, and for both plastic greenhouses equipped with fully opened side vents, the air located between the rows of canopy and ground surfaces remained very slow, not exceeding 0.2 ms-1; for the Venlo glasshouse, the recirculation loop situated above the crop improved the air mixing and induced a good homogenization. Results indicate that the cover material with highest absorptivity, deteriorated the natural ventilation, increasing the air temperature by convection, and reduced the available Photosynthetically Active Radiation.

Eficiencia de trampas pitlight con led para el muestreo de coleoptera nocturnos (insecta) en selvas tropicales

RESUMEN. Se evaluó el uso de trampas de caída con luz portables (pitlight) con diodos emisores de luz (LED) para la captura de Coleoptera nocturnos en una selva tropical, con la finalidad de proveer herramientas eficientes para el monitoreo de insectos. Se comparó la diversidad de familias y morfoespecies recolectada con trampas de caída pasivas (pitfall) y con trampas de caída con luz (pitlight) de tresdistintas longitudes de onda (azul, blanca y amarilla), bajo la hipótesis de que las trampas pitlight son más eficientes, y que los insectos serán más atraídos por las longitudes de onda más cortas y de alta frecuencia. Además, el muestreo se dividió en dos períodos nocturnos de cinco horas, con el objetivo de analizar el tiempo necesario para obtener una colecta significativa. Las recolectas con trampas pitlight fueron notablemente superiores a las pitfall pasivas, y aunque no se encontraron diferencias significativas entre los valores de riqueza, abundancia y diversidad de coleópteros obtenidos con tres colores de LED (azul, blanco, amarillo), ni entre los horarios nocturnos de recolecta, sí se observó una alta disimilitud en la composición de morfoespecies entre los distintos tratamientos. Las trampas pitlight con LED son un método sencillo, portátil y económico que es capaz de obtener una captura eficiente y representativa en periodos de tiempo muy cortos, por lo quese recomienda su uso para el inventario de comunidades de insectos.

Effects of Vildagliptin Add-on Insulin Therapy on Nocturnal Glycemic Variations in Uncontrolled Type 2 Diabetes.

IntroductionTo investigate whether vildagliptin add-on insulin therapy improves glycemic variations in patients with uncontrolled type 2 diabetes (T2D) compared to patients with placebo therapy.MethodsThis was a 24-week, single-center, double-blind, placebo-controlled trial. Inadequately controlled T2D patients treated with insulin therapy were recruited between June 2012 and April 2013. The trial included a 2-week screening period and a 24-week randomized period. Subjects were randomly assigned to a vildagliptin add-on insulin therapy group (n = 17) or a matched placebo group (n = 16). Scheduled visits occurred at weeks 4, 8, 12, 16, 20, and 24. Continuous glucose monitoring (CGM) was performed before and at the endpoint of the study.ResultsA total of 33 subjects were admitted, with 1 patient withdrawing from the placebo group. After 24 weeks of therapy, HbA1c values were significantly reduced at the endpoint in the vildagliptin add-on group. CGM data showed that patients with vildagliptin add-on therapy had a significantly lower 24-h mean glucose concentration and mean amplitude of glycemic excursion (MAGE). At the endpoint of the study, patients in the vildagliptin add-on group had a significantly lower MAGE and standard deviation compared to the control patients during the nocturnal period (0000–0600). A severe hypoglycemic episode was not observed in either group.ConclusionVildagliptin add-on therapy to insulin has the ability to improve glycemic variations, especially during the nocturnal time period, in patients with uncontrolled T2D.

Alteration of plant species assemblages can decrease the transmission potential of malaria mosquitoes.

Knowledge of the link between a vector population's pathogen-transmission potential and its biotic environment can generate more realistic forecasts of disease risk due to environmental change. It also can promote more effective vector control by both conventional and novel means.This study assessed the effect of particular plant species assemblages differing in nectar production on components of the vectorial capacity of the mosquito Anopheles gambiae s.s., an important vector of African malaria.We followed cohorts of mosquitoes for three weeks in greenhouse mesocosms holding nectar-poor and nectar-rich plant species by tracking daily mortalities and estimating daily biting rates and fecundities. At death, a mosquito's insemination status and wing length were determined. These life history traits allowed incorporation of larval dynamics into a vectorial capacity estimate. This new study provided both novel assemblages of putative host plants and a human blood host within a nocturnal period of maximum biting.Survivorship was significantly greater in nectar-rich environments than nectar-poor ones, resulting in greater total fecundity. Daily biting rate and fecundity per female between treatments was not detected. These results translated to greater estimated vectorial capacities in the nectar-rich environment in all four replicates of the experiment (means: 1,089.5 ± 125.2 vs. 518.3 ± 60.6). When mosquito density was made a function of survival and fecundity, rather than held constant, the difference between plant treatments was more pronounced, but so was the variance, so differences were not statistically significant. In the nectar-poor environment, females' survival suffered severely when a blood host was not provided. A sugar-accessibility experiment confirmed that Parthenium hysterophorus is a nectar-poor plant for these mosquitoes.Synthesis and applications. This study, assessing the effect of particular plant species assemblages on the vectorial capacity of malaria mosquitoes, highlights the likelihood that changes in plant communities (e.g. due to introduction of exotic or nectar-rich species) can increase malaria transmission and that a reduction of favourable nectar sources can reduce it. Also, plant communities' data can be used to identify potential high risk areas. Further studies are warranted to explore how and when management of plant species assemblages should be considered as an option in an integrated vector management strategy.

Comparison of intraocular pressure fluctuations before and after ab interno trabeculectomy in pseudoexfoliation glaucoma patients.

PurposeAb interno trabeculectomy (AIT) with the Trabectome has been shown to reduce intraocular pressure (IOP) in eyes with pseudoexfoliation (PEX) glaucoma. Here, we examined the change of IOP fluctuations before and after only AIT or AIT with cataract surgery in PEX patients using the contact lens sensor Triggerfish®.MethodsThis was a prospective open-label study. Twenty-four consecutive patients with PEX glaucoma were included. Twelve patients underwent cataract surgery and AIT (triple-surgery group), and 12 patients underwent only AIT (single-surgery group). In each eye, IOP fluctuations over 24 h were measured with the contact lens sensor before and at 3 months after the surgery. We compared the change of IOP fluctuation before and after operation. We also evaluated the difference in IOP changes between the triple- and single-surgery groups.ResultsAt 3 months after the surgeries, the mean IOP was significantly reduced from 23.5±6.5 mmHg to 14.6±2.8 mmHg in the single-surgery group and from 22.5±3.0 mmHg to 11.5±2.9 mmHg in the triple-surgery group. The mean IOP reduction rate was significantly higher in the triple-surgery group compared to the single-surgery group (p=0.0358). In both groups, the mean range of IOP fluctuations was significantly decreased during nocturnal periods. The mean range of 24 h IOP fluctuations was decreased in the triple-surgery group (p=0.00425), not in the single-surgery group (p=0.970).ConclusionTriple surgery could decrease IOP value and the IOP fluctuations to a greater extent than single surgery in PEX glaucoma patients.

Binge drinking and anxiety at the end of the nocturnal period in alcohol-preferring sP rats.

Previous studies suggested that exposure of Sardinian alcohol-preferring (sP) rats to daily drinking sessions of 1h, during the dark phase of the light/dark cycle, with multiple alcohol concentrations, and unpredictable access to alcohol, resulted in exceptionally high intakes of alcohol when the drinking session occurred over the last hours of the dark phase. Additionally, higher levels of anxiety-related behaviors were observed at the 12th, rather than 1st, hour of the dark phase, suggesting that uncertainty of time of alcohol access and expectation of alcohol availability produced an emotional "distress". The present study was designed to provide pharmacological support to the hypothesis that high alcohol intake under this drinking procedure is secondary to exacerbation of the anxiety-like state of sP rats. To this end, sP rats were initially exposed to daily 1-h drinking sessions during the dark phase and with multiple alcohol concentrations (0%, 10%, 20%, and 30%; v/v); time of alcohol exposure was changed each day and was unpredictable to rats. Rats were then treated acutely with non-sedative doses of diazepam (0, 1, 2, and 3mg/kg; intraperitoneally [i.p.]) before two drinking sessions occurring at the 1st and 12th hour of the dark phase, respectively. Treatment with diazepam was ineffective at the 1st hour; conversely, it selectively reduced alcohol intake (up to 50% at the dose of 3mg/kg) at the 12th hour. The preferential effectiveness of diazepam in reducing alcohol intake when the drinking session occurred at the 12th hour of the dark phase is consistent with the hypothesis that uncertainty of time of alcohol access and expectation of alcohol availability generated an emotional "distress" that rats counterbalanced with high alcohol drinking; the results of the present study are interpreted as the anxiolytic effects of diazepam substituting for those of alcohol, resulting in the observed reduction in alcohol intake.

Temperature variability in the day\u2013night cycle is associated with further intracranial pressure during therapeutic hypothermia

BackgroundTo assess whether circadian patterns of temperature correlate with further values of intracranial pressure (ICP) in severe brain injury treated with hypothermia.MethodsWe retrospectively analyzed temperature values in subarachnoid hemorrhage patients treated with hypothermia by endovascular cooling. The circadian patterns of temperature were correlated with the mean ICP across the following day (ICP24).ResultsWe analyzed data from 17 days of monitoring of three subarachnoid hemorrhage patients that underwent aneurysm coiling, sedation and hypothermia due to refractory intracranial hypertension and/or cerebral vasospasm. ICP24 ranged from 11.5 ± 3.1 to 24.2 ± 6.2 mmHg. The ratio between the coefficient of variation of temperature during the nocturnal period (18:00–6:00) and the preceding diurnal period (6:00–18:00) [temperature variability (TV)] ranged from 0.274 to 1.97. Regression analysis showed that TV correlated with ICP24 (Pearson correlation = −0.861, adjusted R square = 0.725, p < 0.001), and that ICP24 = 6 (4–TV) mmHg or, for 80% prediction interval, {text{ICP}}_{24} = 23.9 - 6.22,times,{text{TV }} pm 1.73,timessqrt {1.06 + (({text{TV}} - 1.1)^{2} /4.49)} mmHg. The results indicate that the occurrence of ICP24 higher than 20 mmHg is unlikely after a day with TV ≥1.0.ConclusionsTV correlates with further ICP during hypothermia regardless the strict range that temperature is maintained. Further studies with larger series could clarify whether intracranial hypertension in severe brain injury can be predicted by analysis of oscillation patterns of autonomic parameters across a period of 24 h or its harmonics.

Rat Running Wheel Behavior Reflects Inflammatory, Orofacial Pain

Background: Our objective was to establish a novel, unbiased metric of inflammatory, orofacial pain. Method: Rats were placed individually into cages equipped with running wheels, and allowed an acclimation period of 17 days. Diurnal and nocturnal voluntary running behaviors were recorded. After day 17, rats were deeply anesthetized and divided into mustard oil, vehicle (mineral oil) and drug (ibuprofen) groups. Injections of mustard oil or mineral oil were made into the vestibule superior to the maxillary molar. Running wheel behavior was recorded for three days following the procedure. Results: After acclimation, the average percentage of running behavior that occurred at night was 94% +/-1% SE. Mustard oil injections caused externally observable, unilateral inflammation. On average, mustard oil injections significantly reduced nocturnal running on the first and second nocturnal periods post-injection. The non-steroidal anti-inflammatory, ibuprofen, significantly improved running behavior during the second nocturnal period, which was abolished when removed during the third nocturnal period. Conclusions: We conclude that unilateral injections of algogens in the vestibule coupled with analysis of nocturnal running behavior is an effective method to measure acute inflammatory pain for three days that mirrors many painful clinical situations. The model could be used as inexpensive, quantitative method to evaluate putative pain relieving therapeutics.

PSB33 sustains photosystem II D1 protein under fluctuating light conditions.

On Earth, solar irradiance varies as the sun rises and sets over the horizon, and sunlight is thus in constant fluctuation, following a slow dark-low-high-low-dark curve. Optimal plant growth and development are dependent on the capacity of plants to acclimate and regulate photosynthesis in response to these changes of light. Little is known of regulative processes for photosynthesis during nocturnal events. The nucleus-encoded plant lineage-specific protein PSB33 has been described as stabilizing the photosystem II complex, especially under light stress conditions, and plants lacking PSB33 have a dysfunctional state transition. To clarify the localization and function of this protein, we used phenomic, biochemical and proteomics approaches in the model plant Arabidopsis. We report that PSB33 is predominantly located in non-appressed thylakoid regions and dynamically associates with a thylakoid protein complex in a light-dependent manner. Moreover, plants lacking PSB33 show an accelerated D1 protein degradation in nocturnal periods, and show severely stunted growth when challenged with fluctuating light. We further show that the function of PSB33 precedes the STN7 kinase to regulate or balance the excitation energy of photosystems I and II in fluctuating light conditions.

Numerical prediction of thermal environment and energy consumption of three different greenhouses under hot and semi-arid climate

The evaluation of the thermal performance of a greenhouse requires an understanding of the energy exchanges between its components. In recent years, Computational Fluid Dynamics (CFD) proved to be efficient to predict the microclimate inside greenhouses, but few CFD works analyzed hot and arid climatic conditions. The aim of the present study is to investigate the impact of such specific conditions prevailing in the southern Mediterranean basin considering three different unheated greenhouses equipped with rows of canopy (tunnel, Venlo and plastic vertical wall greenhouse). 2D simulations were conducted in order to estimate the influence of the greenhouse geometry and cover material on the energy balance, focusing in particular on the heat losses. To establish the boundary conditions and validate the model, experiments were launched inside the greenhouses. Simulations were conducted for two contrasted conditions: the nocturnal period when the energy performance of each type of greenhouse was investigated, and the diurnal period for which a solar day was simulated taking account of natural ventilation. A good agreement was found with experiments concerning the temperature profiles and the energy losses. The predicted stable flow patterns slightly differed from one greenhouse to another for each condition: during the night they all disclosed two convective loops sweeping the floor, rising along the middle of the greenhouse, cooling down along the roof and moving down along the sidewalls of the greenhouse, while during the day flow patterns were strongly impacted by the vent openings. The obtained values (temperature and velocity) were coherent with results found in the literature for different greenhouse types and sizes. The developed tool offers potential applications in research on greenhouse climate to assess different cover material performances. It could also be used to investigate the energy consumption and partition for different greenhouse shapes, different crop densities different growth stages.

English

This research examined nocturnal and diurnal bird migration using an automated marine radar system during three autumn (August 15 to November 17) and three spring (March 15 to June 1) periods in 2007–2010 along the lower Texas coast. We quantified migration timing, magnitude, and flight altitudes for over 14 million targets during 16,360 h of radar operation. Autumn migration was prolonged in contrast to spring migration, which was concentrated within a four-week period in mid–April to mid–May. Mean migration traffic rate in autumn averaged 1,186 targets km-1 h-1 and was 46% greater than spring. Migration traffic rates at our northern site were at least 62% higher than at our southern site. We found bird passage to be similar between diurnal and nocturnal periods in autumn, but predominately nocturnal (68% of targets) in spring. Mean flight altitudes were 10-33% higher in spring than autumn. Our results confirm that the lower Gulf coast of Texas is a significant migration corridor concentrating millions of birds during migration. This new information on temporal and spatial dynamics of migration provides guidance for the placement and operation of wind power developments to reduce the risk to migratory birds along the lower Texas coast. Key words: Bird migration, coast, flight altitude, marine radar, migration traffic rates, Texas, wind power.

Morningness, Eveningness And Stress Perception In Physical Education Students

Objective: to identify the stress levels and sleeping habits of students from the Physical Education college during the diurnal and nocturnal periods.&#x0D; Method: this is an exploratory and descriptive study with 103 subjects. Data were collected through the Lipp Stress Symptom Inventory and the Horne &amp; Östberg Morningness-Eveningness Identification Questionnaire, and sociodemographic data.&#x0D; Results: The stress indexes showed 53.40% of students without stress and 46.6% with stress. When comparing gender and stress using the chi-square test, one obtained (p=0.0411), indicating that women are more stressed than men. There were 61.1% of students classified with indifferent chronotype. Among the students, 80.4% from the diurnal period were not suitable for the chronotype, as well as 74.5% of the students from the nocturnal period were not either.&#x0D; Conclusion: the majority of the students did not present the chronotype adequate for the study schedule and they presented stress, being more frequent in the female group.

Diel habitat use patterns of a marine apex predator (tiger shark, Galeocerdo cuvier) at a high use area exposed to dive tourism

Knowledge of the diel spatial ecology of wild animals is of great interest to ecologists and relevant to resource management and conservation. Sharks are generally considered to be more active during nocturnal periods than during the day; however, few studies have empirically evaluated diel variation in shark habitat use and how anthropogenic disturbances may influence these patterns. In the western central Atlantic Ocean, tiger sharks (Galeocerdo cuvier) are highly abundant in the shallow waters of the Little Bahama Bank, Bahamas. Within the northwest edge of the Bank, there is an area nicknamed “Tiger Beach,” where tiger sharks are provisioned year-round at spatially discrete ecotourism dive sites spanning ~1.5km2. In this study, we used an array of acoustic receivers encircling an area of 102.4km2 to evaluate for potential differences in diel spatial habitat use patterns for 42 tagged tiger sharks at Tiger Beach and the surrounding area. Using tracking data from 24 June 2014 to 13 May 2015, we evaluated spatial and diel patterns of shark activity space, centers of activity, residency and the daily proportion of sharks detected within the array. Sharks were detected during both day and night with no significant diel differences in habitat use metrics across the array, although spatial differences in residency existed. Four sharks accounted for 53.8% of residency data throughout the tracking period, with the majority of sharks primarily entering and exiting the array, except during summer months when the most of the tagged tiger sharks were absent from the array. We also found limited empirical support for hypothesized effects of provisioning tourism on tiger shark habitat use. However, additional research at finer, individual scales, may be needed to better resolve the potential influence of provisioning on tiger sharks at Tiger Beach.

Ability to adjust nocturnal fat oxidation in response to overfeeding predicts 5‐year weight gain in adults

ObjectiveTo determine whether metabolic responses to short-term overfeeding predict longitudinal changes in body weight.Methods24h energy expenditure (EE) and substrate utilization were measured at baseline in a room calorimeter following 3d of eucaloric and hypercaloric feeding (40% excess) in a sample of lean adults (n: 34; age: 28±2 years; body mass index: 22±3 kg/m2). Body mass and fat mass (DXA) were measured annually for 5yrs. Regression analyses examined whether changes in EE and fuel use with overfeeding predicted body weight and composition changes over 5yrs.ResultsOverfeeding increased EE and reduced fat oxidation when examined over the 24h, waking, and nocturnal periods. Absolute change in body mass over 5y was 3.0±0.6 kg (average rate of change = 0.7±0.1 kg per year, p<0.001). Lower nocturnal (but not 24h or waking) fat oxidation (r =−0.42, p=0.01) and EE (r=−0.33, p =0.05) with overfeeding were the strongest predictors of 5y weight gain. When adjusted for covariates, changes in nocturnal fat oxidation and EE with overfeeding predicted 41% of the variance weight change (p=0.02).ConclusionsFailure to maintain fat oxidation at night following a period of overfeeding appears to be associated with a metabolic phenotype favoring weight gain.