Prevalence,Serovars and Antimicrobial Susceptibility of Salmonella spp. from Wild and Domestic Green Iguanas (Iguana iguana) in Grenada,West Indies

Cloacal swabs from 62 green iguanas (Iguana iguana), including 47 wild and 15 domestic ones from five parishes of Grenada, were sampled during a 4‐month period of January to April 2013 and examined by enrichment and selective culture for the presence of Salmonella spp. Fifty‐five per cent of the animals were positive, and eight serovars of Salmonella were isolated. The most common serovar was Rubislaw (58.8%), a serovar found recently in many cane toads in Grenada, followed by Oranienburg (14.7%), a serovar that has been causing serious human disease outbreaks in Japan. Serovar IV:48:g,z₅₁:‐ (formerly, S. Marina) highly invasive and known for serious infections in children in the United States, constituted 11.8% of the isolates, all of them being from domestic green iguanas. Salmonella Newport, a serovar recently found in a blue land crab in Grenada, comprised 11.8% of the isolates from the green iguanas. The remaining four less frequent serovars included S. Javiana and S. Glostrup. Antimicrobial susceptibility tests conducted by a disc diffusion method against amoxicillin–clavulanic acid, ampicillin, cefotaxime, ceftazidime, ciprofloxacin, enrofloxacin, gentamicin, nalidixic acid, streptomycin, tetracycline and trimethoprim–sulfamethoxazole showed that drug resistance is minimal, with intermediate susceptibility, mainly to streptomycin, tetracycline and cefotaxime. This is the first report of isolation and antimicrobial susceptibilities of various Salmonella serovars from wild and domestic green iguanas in Grenada, West Indies.     

The leucogram as an indicator off marine-cultured rainbow trout, Oncorhynchus mykiss (Walbaum), health in The Netherlands

During a longitudinal survey from June until October 1987 cytological blood parameters of smoltified marine cultured rainbow trout, Oncorhynchus mykiss (Walbaum), were monitored. In this period, the trout were exposed to environmental stress resulting in summer mortality. The statistical analyses showed that the observed summer mortality was preceeded by a shift in the relative abundance of different peripheral white blood cells (PWBCs), from lymphocytic to extremely granulocytic, which was mainly attributed to mature granulocytes. It was concluded that changes in relative abundance of PWBCs can predict health disturbances in marine-cultured rainbow trout.     

Salinity tolerance during early development of threatened Murray hardyhead (Craterocephalus fluviatilis) to guide environmental watering

1. The worldwide reduction in wetlands has led to the large‐scale decline of wetland‐dependent species. In Australia, to redress some of the decline, partial restoration of the hydrology of a small number of wetlands has been attempted using allocations of environmental water.
2. A common goal of the watering is the maintenance and enhancement of native fish communities, which historically have included populations of the salt tolerant Murray hardyhead (Craterocephalus fluviatilis), a small, short‐lived fish, endemic to the lower Murray–Darling Basin.
3. Despite the addition of environmental water to several sites at which the species is known to persist, populations continue to decline. This decline is, at least in part, suspected to be a consequence of salinities that conflict with the breeding ecology and survival of early life stages.
4. Here the effect of salinity on egg hatch rate and the upper salinity tolerance of larval and juvenile Murray hardyhead was determined under laboratory conditions. It was found that eggs were vulnerable to elevated salinities, whereas juveniles were capable of tolerating salinities up to 105 ppt.
5. Based on the results of the experiment, brackish wetlands managed for Murray hardyhead should be maintained, where possible, between 12 and 45 ppt. Such a salinity regime will necessitate less intensive management of salinity, and a reduced volume of environmental water, providing both environmental and fiscal benefits. The research highlights the benefits of investment in targeted research.

     

Ecosystem‐based fisheries management: A perspective on the critique and development of the concept

The concept of ecosystem‐based fisheries management (EBFM) has been subjected to debate since it was introduced in the late 1990s. The development of the concept seems to follow two separate but simultaneous trajectories of increased popularity but also sustained critique. This paper offers an analysis of potential mechanisms behind these disparate trajectories by drawing on a theoretical framework from science and technology studies (STS) centred around "black box" and actor‐network theory. To support our analysis, we perform an exploratory literature review of how the EBFM concept has been used in a selection of high impact fisheries research papers. We find that the popularity of EBFM does not guarantee its integrity, usefulness or analytical insight, but also that persistent critique of how the concept is used seems to be driving some change. We think that a continued trajectory of increased understanding, contextualization and discernibility of EBFM can help overcome the considerable ambiguity associated with the concept and make it increasingly useful to fisheries management. This means moving away from routine use of the term towards a practicable and tangible approach to improve fisheries sustainability.     

Influence of wetland networks on bat activity in mixed-use landscapes

Parks and other protected lands can provide important source habitat and act as valuable dispersal corridors in urbanizing environments. However, most wetlands within protected areas are managed in isolation without consideration of the broader landscape connections. We studied the importance of wetland habitat connectivity and landscape context to bat activity in five National Parks along a gradient of increasing urbanization within the Mid-Atlantic United States. Ninety-six Anabat stations were set up throughout the parks, from which we derived the characteristic spatial scales at which bat activity was associated with wetlands. This information was used in a graph theoretic framework to construct network models of potential landscape connectivity for those species that had positive associations with wetland land cover. We found that the importance of wetlands as a predictor of bat activity varied on a species-by-species basis and increased when network measures were used that accounted for connected area in a broad spatial context. The results demonstrate that both area and connectivity of wetland foraging habitat may act as orthogonal variables to availability of roosting habitat in explaining the distribution of highly mobile species. We use the results to illustrate the value of network analysis to guide the coordinated management of two of the parks’ most valued natural resources - wetlands and bats.     

Non-ideal Behavior During Complete Dissolution of Organic Immiscible Liquid: 2. Ideal Porous Media

Column experiments were conducted using ideal natural sands and stainless-steel beads to examine the complete dissolution behavior of an organic immiscible liquid. Trichloroethene was used as the representative organic liquid. The elution curves exhibited multi-step behavior, with multiple extended periods of relatively constant contaminant flux. These secondary steady-state stages occurred at concentrations several orders-of-magnitude below aqueous solubility for the well-sorted sands. In contrast, the secondary steady-state stages occurred within 1 log of aqueous solubility for the poorly sorted sand. The non-ideal behavior is hypothesized to result from constraints to hydraulic accessibility of the organic liquid to flowing water, which may be expected to be mediated by the pore-scale configuration of the flow field and the fluid phases.     

Effect of Feeding Frequency and Romet-Medicated Feed on Survival, Antibody Response, and Weight Gain of Fingerling Channel Catfish Ictalurus punctatus after Natural Exposure to Edwardsiella ictaluri

Abstract The efficacy of restrictive feeding regimes and Romet®-medicated feed (formulated at 40.5-mg Romet-30 premix/kg feed) fed at 2.0% body weight was evaluated under field trial conditions for the treatment of naturally induced Edwardsiella ictaluri infections in fingerling channel catfish. After detection of an Edwardsiella ictaluri epizootic, fish were fed medicated and non-medicated feed every day, every other day and every third day for the duration of the experiment. In addition, experimental treatments also included fish that were completely withheld from feed and those provided Romet-medicated feed for five consecutive days followed by non-medicated feed fed daily. Feeding frequency and diet significantly affected survival and weight gain. Survival was greatest among fish that were completely withheld from feed or that were fed medicated feed every other or every third day. The use of non-medicated feed every other or every third day was equally as effective for reducing Edwardsiella ictaluri associated mortalities as feeding Romet-medicated feed on a daily basis. Feeding fish Romet-medicated feed for five consecutive days was not an effective treatment. Agglutinating antibody titers against Edwardsiella ictaluri were significantly lower in all groups of fish fed Romet-medicated feed for the duration of the experiment. These data indicate that feeding frequency is a primary factor affecting the severity of Edwardsiella ictaluri infection and that prolonged consumption of Romet-medicated feed may suppress antibody production.     

Effect of row spacing,growth stage,and nitrogen rate on spectral irradiance in winter wheat

Soil reflectance affects spectral irradiance measurements taken in winter wheat at early stages of growth when percent cover is low. The objective of this study was to determine the critical percent vegetation coverage needed for forage nitrogen (N) uptake calibration with indirect spectral irradiance measurements. Two field experiments were conducted at Tipton and Perkins, OK in October 1996. The effect of row spacing (15.2, 19.0, 25.4, and 30.5 cm) and growth stage (Feekes 4 and 5) under various N fertilizer rates (0, 56, 112, and 168 kg N ha^‐1) on spectral irradiance measurements from wheat was evaluated. The normalized difference vegetative index (NDVI) was used to characterize wheat canopy irradiance. In general, NDVI decreased with increasing row spacing and increased with N fertilizer rate at Feekes growth stage 4. Row spacing and N rate were independent of each other since no significant interaction was found. High correlation (r=0.81–0.98) was observed between NDVI and vegetation coverage. Percent vegetation coverage was a good predictor of the other dependent variables including forage dry matter, and total N uptake, which could indirectly be determined using NDVI. The coefficients of variation (CV's) from NDVI values decreased with increasing vegetation coverage suggesting that less variable NDVI values (CV less than 10%) might be obtained from plots where vegetation coverage exceeds 50%.     

Experimental transmission of Hepatozoon americanum to rodents

Laboratory-raised cotton rats (Sigmodon hispidus), outbred white mice (Mus musculus), and C57BL/6J-Lystbg-J/J mice (M. musculus) that were administered approximately 50 sporulated oocysts of Hepatozoon americanum (AF176836) by gavage developed inflammatory lesions containing parasitic cystozoites in cardiac and skeletal muscle, kidney, and lung. Sprague-Dawley rats (Rattus norvegicus) similarly exposed showed no evidence of infection. Cystozoites were first detected by histopathologic examination four weeks after exposure to oocysts. Globular, PAS-positive material accumulated around the cystozoites as the duration of infection lengthened. Nested PCR analysis of tissues collected 16 weeks post-exposure was positive for the 18S rRNA Hepatozoon sp. gene and the DNA sequence of the fragment amplified was 99.6% and 99.8% identical to H. americanum sequences previously reported from naturally-infected dogs (AF176836 and AY864676, respectively). Merogonous and gamontogonous stages of the parasite were not detected in any of the cystozoite-infected rodents.     

Effects of inorganic and organic copper supplemented to first-calf cows on cow reproduction and calf health and performance

Two experiments were conducted to determine whether the supplementation of Cu in the organic or inorganic form to 2-yr-old cows, before and after calving, affects reproduction rate, calf health and performance, passive transfer of immunoglobulin, or liver and serum Cu concentrations compared with unsupplemented controls. Cows (n = 75 in 1997; n = 120 in 1998) were randomly assigned by estimated calving date and body condition score to one of three treatments: 1) Control, control; 2) Inorganic, inorganic Cu supplement (200 mg Cu from CuSO4); 3) Organic, organic Cu supplement (100 mg Cu from AvailaCu). In 1998, a fourth treatment was added; 4) CU-ZN, organic Cu and Zn (400 mg Zn from AvailaZn in the Organic diet). Cows were fed a hay-based diet and individually fed supplements for approximately 45 d before and 60 d after calving (approximately January 15 to May 15 each year). Liver biopsies were obtained from cows before supplementation began, and from cows and calves at 10 and 30 d after calving. Blood samples were obtained from both cows and calves at calving, and colostrum samples were collected for IgG and mineral content. Cow liver Cu concentrations before supplementation began were 58 mg/kg in 1997 and 40 mg/kg (DM basis) in 1998. By 10 d after calving, liver Cu concentrations of Control cows had decreased (P < 0.05) to 24 mg/kg (Cu deficient) in both years, whereas liver Cu concentrations of Cu-supplemented cows increased (P < 0.05) in both years. Calf liver Cu concentrations at 10 d of age were similar (P > 0.10) for all treatment groups. No differences (P > 0.10) were found in colostrum Cu concentrations, or in calf health among treatments. No differences (P > 0.10) were found in cow BW change, calf serum Cu concentrations, calf weaning weights, or in cow 60-d pregnancy rates among treatments in either year. In 1998, cows in the Organic group had higher (P < 0.05) 30-d pregnancy rate than Control cows. Neither serum samples nor placental tissue were reliable indicators of Cu status in cows. Feeding supplemental Cu (either inorganic, organic, or organic with extra Zn) to cows with liver Cu concentrations of approximately 50 mg/kg before calving did not improve cow 60-d pregnancy rates or the health and performance of their calves when compared with unsupplemented cows.