Spatio‐temporal analyses of marine predator diets from data‐rich and data‐limited systems

Accounting for variation in prey mortality and predator metabolic potential arising from spatial variation in consumption is an important task in ecology and resource management. However, there is no statistical method for processing stomach content data that accounts for fine‐scale spatio‐temporal structure while expanding individual stomach samples to population‐level estimates of predation. Therefore, we developed an approach that fits a spatio‐temporal model to both prey‐biomass‐per‐predator‐biomass data (i.e. the ratio of prey biomass in stomachs to predator weight) and predator biomass survey data, to predict “predator‐expanded‐stomach‐contents” (PESCs). PESC estimates can be used to visualize either the annual landscape of PESCs (spatio‐temporal variation), or can be aggregated across space to calculate annual variation in diet proportions (variation among prey items and among years). We demonstrated our approach in two contrasting scenarios: a data‐rich situation involving eastern Bering Sea (EBS) large‐size walleye pollock (Gadus chalcogrammus, Gadidae) for 1992–2015; and a data‐limited situation involving West Florida Shelf red grouper (Epinephelus morio, Epinephelidae) for 2011–2015. Large walleye pollock PESC was predicted to be higher in very warm years on the Middle Shelf of the EBS, where food is abundant. Red grouper PESC was variable in north‐western Florida waters, presumably due to spatio‐temporal variation in harmful algal bloom severity. Our approach can be employed to parameterize or validate diverse ecosystem models, and can serve to address many fundamental ecological questions, such as providing an improved understanding of how climate‐driven changes in spatial overlap between predator and prey distributions might influence predation pressure.     

Population abundance and habitat utilization of bottlenose dolphins in the Mississippi Sound

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Changes in the hypothalamus and adjacent ependyma after hormonal stimulation of the ovaries in ewes]

Superovulation treatment leaves alternations in the controlling regions of the hypothalamus and in the adjacent ependyme after ovulation. The test ewes were synchronized with Agelin (20 mg chlorsuperlutin in one vaginal sponge) and stimulated (after the removal of the sponges) with 750 IU PMSG + 750 IU HCG and with 1000 IU HCG and 750 IU PMSG + 5 ml Antisergon (goat antiserum against PMSG), administered 68 hours after PMSG (i.e. 40 hours after HCG). The control ewes were in different stages of the ovarial cycle. The experimental ewes were killed 120 to 130 hours after the start of stimulation. Routine histological techniques were used to treat the brain samples; this treatment was followed by assessment under light microscope. The ependyme epithelium of the third cerebral chamber was studied under scanning microscope. Preparations with different FSH:LH ratios had different effects on the nucleus ventromedialis. Antisergon administration influenced the secretion of NPV (prevented persistent stimulation), which was observed after administration of PMSG + HCG. On the surface of the lower part of the third cerebral chamber the administration of Antisergon slowed the formation of the miniblebs. Supraependyme cells disappeared after stimulation for superovulation.     

Dye injection for predicting pesticide movement in micro-irrigated polyethylene film mulch beds

A new method is described for tracing water movement in polyethylene film covered soil beds. Dye was delivered via a drip tape micro-irrigation system which was placed in the bed as the soil beds were shaped and covered with polyethylene film. The dye was injected into the system and irrigated with water for 4-24 h at 0.41-1.38 bar (41-138 kPa) pressure depending on the experiment. The dye appeared as blue circles on the soil surface within 20 min of injection and produced a three-dimensional pattern in the soil profile. Injection-irrigation-pressure scenarios were evaluated by measuring dye movement directly below and between emitters by sliding fabricated blades vertically into the bed at the desired examination point and excavating the soil away from the blade. The dye typically produced a U shape on the face of the bed and the area was calculated for each of these exposed faces. The area increased as the length of irrigation and water pressure increased. Interrupted irrigation (pulsing) scenarios did not alter the calculated areas encompassed by the dye compared to uninterrupted irrigation scenarios. The blue dye provided a direct, inexpensive and easy method of visualizing water movement in soil beds. This information will be used to optimize application of emulsifiable plant-care products in polyethylene film mulch beds.     

Long-lasting anticryptosporidial activity of nitazoxanide in an immunosuppressed rat model

Cryptosporidium parvum, Tyzzer, 1912 is identified as a common cause of diarrhoea in immunocompetent individuals. In immunocompromised, especially HIV-infected subjects, cryptosporidiosis causes severe chronic diarrhoea. In this study, nitazoxanide (NTZ) was compared for curative activity with sinefungin (SNF) and paromomycin (PRM) in immunosuppressed rats, a screening model for anticryptosporidial agents. NTZ at either 50 mg/kg/day, 100 mg/kg/day or 200 mg/kg/day resulted in seven days in a dose-dependent inhibition of oocyst shedding similar to that obtained with SNF (10 mg/kg/day) and PRM (100 mg/kg/day). Further discontinuation of SNF or PRM 100 mg/kg/day therapy resulted in early relapse of oocyst shedding which reached the pre-treatment levels in 2-4 days. In contrast, seven days after discontinuation of therapy, shedding inhibition was unchanged in NTZ-treated rats. Data prompt further assessment of the activity of NTZ on sequestered C. parvum.     

Direct comparison of pollen-mediated movement of native and engineered genes

Despite the commercial approval of twenty-five transgenic crops in the U.S. as of mid-1996, concern is still being expressed regarding the potential risks associated with genetically engineered crops. One recurring issue is the possibility of pollen-mediated escape of engineered genes into populations of crop wild relatives. To address this concern, the scientific community has depended on literature on pollen dispersal generated from non-transgenic organisms. Utilization of this information requires the assumption that the pollen mediated movement of native and transgenes is the same. To test the validity of this assumption, we directly compared the pollen-mediated gene movement of native and engineered marker genes using melon plants (Cucumis melo L.) expressing dominant morphological and transgenic traits. Movement into both contiguous border plots and non-contiguous satellite plots were monitored. Dispersal of the native gene and transgene into the satellite plots was identical. Dispersal of the two traits into the plot borders was nearly identical. Of the nearly 4600 seedlings screened for both morphological (presence of green vs. virescent cotyledons) and transgene movement (presence of NPT II protein by ELISA), in no case was the NPT II gene observed in the absence of green cotyledons. However, 39 seedlings were green but did not express NPT II as measured by ELISA. PCR analysis revealed transgene inactivation as a cause of the NPT II ELISA-seedlings. This revised version was published online in July 2006 with corrections to the Cover Date.     

Randomized field trial comparing the efficacy of florfenicol and oxytetracycline in a natural outbreak of calf pneumonia using lung reaeration as a cure criterion

BackgroundRespiratory infections are the main indication for antimicrobial use in calves. Optimal treatment duration currently is unknown, but shorter duration would likely decrease selection for antimicrobial resistance.Hypothesis/ObjectivesDetermine differences in cure rate and healing time between animals treated with florfenicol and oxytetracycline in a natural outbreak of respiratory disease using reaeration observed on thoracic ultrasound examination as healing criterion.AnimalsCommercial farm housing 130, 3 to 9 month old Belgian blue beef calves.MethodsRandomized clinical trial during an outbreak of respiratory disease. Metaphylactic treatment was initiated, randomly treating animals with either florfenicol or oxytetracycline. Ultrasonographic follow‐up was done the first day and every other day for a 14‐day period. At the individual animal level, treatment was discontinued when reaeration of the lungs occurred. Differences in cure rate and healing time were determined.ResultsOf the 130 animals studied, 67.7% developed a lung consolidation ≥0.5 cm. The mean ultrasonographic healing time was 2.5 days in the florfenicol group compared to 3.1 days in the oxytetracycline group (P = .04). After single treatment, 80.6% and 60.3% had no consolidations in the florfenicol and oxytetracycline groups, respectively (P = .01). A Mycoplasma bovis strain was genetically and phenotypically determined to be susceptible to both antimicrobials.Conclusions and Clinical ImportanceUltrasonographic lung reaeration shows potential as a cure criterion to rationalize antimicrobial use for outbreaks of pneumonia. In our study, florfenicol resulted in a faster cure and higher reduction in antimicrobial usage than did oxytetracycline.