Coupling stable isotope studies with food web manipulations to predict the effects of exotic fish: lessons from Cuatro Ciénegas,Mexico

• 1. Exotic species threaten native species worldwide, but their impacts are difficult to predict.
• 2. Stable isotope analysis was combined with field competition experiments to predict how an invasive African cichlid fish, Hemichromis guttatus, might affect native fish in the desert springs of Cuatro Ciénegas, Mexico.
• 3. Stable isotope analysis suggested diet overlap between the invader and juvenile endemic cichlids, and field experiments verified that the invader reduces growth rates of the juvenile endemics through competition, but has smaller effects on adults.
• 4. Competition between juvenile endemic cichlids and the invader was asymmetric, with the exotic out‐competing the native, suggesting the potential for competitive exclusion if the invasion is not stopped.
• 5. These results suggest that exotic removal programmes in Cuatro Ciénegas should focus on removing/reducing populations of the exotic cichlid in habitats where juvenile native cichlids are concentrated.
• 6. This approach could help focus efforts to manage exotic species before populations of native species have crashed, when it is too late to intervene.

Copyright © 2011 John Wiley & Sons, Ltd.     

Surface Water Quality Impacts of Conservation Tillage Practices on Burley Tobacco Production Systems in Southwest Virginia

A plot-scale, rainfall-simulation study measured edge-of-field pollutant losses from conventional-till, strip-till, and no-till treatments in a burley tobacco production system. The field experiment results show that the conventional-till treatment yielded more total runoff than strip- and no-till treatments. Compared to the conventional-till treatment, both no-till and strip-till reduced the total mass losses of total suspended solids (TSS), total nitrogen (TN), total Kjeldahl nitrogen (TKN), nitrate (NO-N), ammonia (NH₃-N), total phosphorus (TP), orthophosphate (PO₄-P), and the insecticide chlorpyrifos in runoff. Although statistical analyses indicated that there was no significant difference between the no-till and strip-till practices, the no-till practice consistently yielded less edge-of-field pollutant loss than the strip-till practice. This research reinforces the body of knowledge documenting the effectiveness of conservation-tillage practices in reducing edge-of-field pollutant losses.     

Simultaneous quantification of eight biogenic amine compounds in tuna by matrix solid-phase dispersion followed by HPLC-orbitrap mass spectrometry

A method for the extraction of agmatine, cadaverine, histamine, phenyethylamine, putrescine, tryptamine, tyramine, and urocanic acid from canned tuna and frozen tuna loin matrices by matrix solid-phase dispersion, followed by separation and quantification of these compounds by ultrahigh-performance hydrophilic interaction chromatography (UHPLC-HILIC) with orbitrap mass spectrometric detection, is described. Tuna samples are dispersed in a CN-silica sorbent and eluted with a mixture of aqueous ammonium formate buffer and acetonitrile. Separation and detection are carried out on an Agilent 1200 high-performance liquid chromatograph coupled to a Thermo Exactive orbitrap mass spectrometer, and metformin is used as the internal standard. Spike recoveries are determined across a range of 20-100 ppm for each compound, and the method is validated with respect to linearity, reproducibility, accuracy, and limits of quantitation and detection. The method is demonstrated to be suitable for use in quantifying these target compounds in the studied matrices.     

Mortality associated with melarsomine dihydrochloride administration in two North American river otters (Lontra canadensis) and a red panda (Ailurus fulgens fulgens).

Two adult North American river otters (Lontra canadensis) and an adult red panda (Ailurus fulgens fulgens) at three separate institutions died within 22 hr after receiving single 2.5- to 2.7-mg/kg doses of melarsomine dihydrochloride administered in the epaxial musculature as a treatment for filarid nematodes. One otter had a suspected Dirofilaria immitis infection, the other had a confirmed D. lutrae infection, and the red panda had a confirmed Dirofilaria sp. infection, presumably with D. immitis. Postmortem examinations revealed similar gross lesions, although they were less severe in the red panda. The trachea and primary bronchi contained abundant foamy fluid, the lungs were mottled with areas of consolidation, and the pulmonary parenchyma exuded abundant fluid at the cut section. Histologic evaluation revealed acute pulmonary edema, which resulted in respiratory failure and death. There may have been direct pulmonary cellular toxicity of melarsomine dihydrochloride or a severe systemic anaphylactic reaction to antigens released after parasite death. An idiosyncratic drug reaction or a low therapeutic index of melarsomine probably caused the death of the three individuals. Melarsomine dihydrochloride use should be avoided in North American river otters and red pandas.     

Presumptive Intramural Gastric Hemorrhage Secondary to Rodenticide Intoxication in a Dog

A dog being treated for demodicosis with ivermectin was presented for intermittent vomiting. The vomiting progressed to hematemesis and an underlying coagulopathy was diagnosed. The etiology of the coagulopathy was determined to be ingested brodifacoum. Ultrasound evaluation of the abdomen revealed thickened gastric wall that was suspected to be intramural hemorrhage. Most likely, the intramural hemorrhage and resulting thickening of the stomach wall led to the clinical signs and metabolic alkalosis. This case represents an typical presentation of hemorrhage secondary to rodenticide intoxication. (J Vet Emerg Crit Care 2001; 11(1):27–31, 2001).     

Picric Acid Degradation in Sediments from the Louisiana Army Ammunition Plant

Picric acid is an explosive historically produced and disposed at the Louisiana Army Ammunition Plant (LAAP) in northern Louisiana. The potential for natural degradation of picric acid was investigated by creating picric-acid slurries with four LAAP sediments of variable composition and monitoring for up to 98 days. The concentrations of picric acid decreased rapidly in all slurries during the first day, attributed to adsorption, followed by slower decreases in some samples due to degradation. Degradation in unsterilized slurries was nearly complete within 80 days for two of the four sediments. Increases in nitrite and nitrate concentration over time were proportional to the loss of picric acid and indicate that at least two of the three nitrite groups were removed from the picric acid molecule. The absence of significant concentrations of compounds with a mass greater than 100 amu in the final solutions suggests that all three nitrite groups were removed. No correlation was found between the degree of degradation and grain size, clay content, organic content, carbonate content, or a suite of element concentrations in the sediment. Degradation in sterilized samples was minimal for all sediment slurries, indicating microbial activity as the primary mechanism of degradation.     

Comparison of direct immunofluorescence, immunoassays, and fecal flotation for detection of Cryptosporidium spp. and Giardia spp. in naturally exposed cats in 4 Northern California animal shelters

BACKGROUND: Giardia spp. and Cryptosporidium spp. are common intestinal protozoan parasites in domestic cats. Few studies have critically evaluated the performance characteristics of commercially available immunoassays for detection of these organisms in the cat. HYPOTHESIS: Human-based immunoassays are suboptimal for the detection of Giardia spp. and Cryptosporidium spp. in cats. ANIMALS: Three-hundred-and-forty-four cats with diarrheic and nondiarrheic fecal specimens at 4 northern California animal shelters. METHODS: A fecal specimen was collected from each cat in a case-controlled fashion. Fecal specimens were tested for Giardia spp. and Cryptosporidium spp. by using centrifugation flotation and 5 commercially available immunoassays (SNAP Giardia, ProSpecT Giardia Microplate Assay, ProSpecT Cryptosporidium Microplate Assay, ImmunoCard STAT! Cryptosporidium/ Giardia Rapid Assay, and Xpect Giardia/Cryptosporidium). Results were compared with a reference standard, the MeriFluor direct immunofluorescence assay. RESULTS: Overall prevalences of Giardia spp. and Cryptosporidium spp. were 9.8 and 4.7%, respectively. The ProSpecT Microplate Assay had the highest sensitivities and specificities for Giardia spp. (91.2 and 99.4%) and Cryptosporidum spp. (71.4 and 96.7%), respectively. The SNAP Giardia antigen assay was easier to use and equally sensitive (85.3%) and specific (100%) to fecal flotation. CONCLUSIONS AND CLINICAL IMPORTANCE: Caution should be exercised when using human-based immunoassays for the diagnosis of Giardia and Cryptosporidium spp. in cats. Fecal flotation remains a useful method for detection of Giardia spp., can be used to detect other parasites, and has a sensitivity of 97.8% for detection of Giardia spp. when combined with the SNAP Giardia immunoassay.     

Factors to consider in Micronesian food-based interventions: a case study of preventing vitamin A deficiency

BACKGROUND: Many factors need to be considered in a food-based intervention. Vitamin A deficiency and chronic diseases, such as diabetes, heart disease and cancer, have become serious problems in the Federated States of Micronesia (FSM) following the decreased production and consumption of locally grown foods. However, agricultural and social conditions are still favourable for local food production. AIM: To identify key factors to consider in a Micronesian food-based intervention focusing on increased production and consumption of four major Micronesian staple foods: banana, breadfruit, giant swamp taro and pandanus. METHODS: Ethnographic methods including key informant interviews and a literature review. RESULTS: Pacific and Micronesian values, concepts of food and disease, and food classifications differ sharply from Western concepts. There are few FSM professionals with nutrition expertise. Traditional foods and food cultivars vary in nutrient content, consumption level, cost, availability, status, convenience in growing, storing and cooking, and organoleptic factors. CONCLUSIONS: A systematic consideration of the factors that relate to a food-based intervention is critical to its success. The evaluation of which food and cultivar of that food that might be most effectively promoted is also critical. Regional differences, for example FSM inter-island differences between the staple foods and cultivars, must be considered carefully. The evaluation framework presented here may be relevant to Pacific Island and other countries with similar foods where food-based interventions are being planned. An ethnographic approach was found to be essential in understanding the cultural context and in data collection and analysis.