Islands in the forest: effects of patch size and isolation on farmland bird species richness and community composition of farmland patches in forest landscapes

Landscape Ecology - Theory predicts that species diversity of isolated habitat patches depends on patch size and isolation. However, there are few previous studies of how patch size and isolation...     

Nitrogen Fertilizer Management Practices to Reduce N<Subscript>2</Subscript>O Emissions from Irrigated Processing Potato in Manitoba

Nitrogen fertilizer practices affect nitrous oxide (N₂O) emissions from agricultural soils. The “4R” nutrient stewardship framework of using N fertilizer at the right rate, right source, right placement and right time can reduce N₂O emissions while maintaining or improving yield of field crops, but understanding of how the various factors affect N₂O emissions from irrigated processing potato is lacking. We examined the effects of selected 4R practices on emissions, using results from two irrigated processing potato studies each conducted in 2011 and 2012 in Manitoba, Canada. Experiment 1 examined combinations of source (urea, ESN), placement (pre-plant incorporation [PPI], banding), and rate (100 and 200 kg N ha^-1) on a clay loam soil. Experiment 2 examined timing and source treatment combinations (urea PPI, ESN PPI, urea split, urea split/fertigation) on a loamy fine sandy soil. For Experiment 1, use of ESN at 200 kg ha^-1 did not reduce area-, yield- and applied fertilizer N- based N₂O emissions compared to urea at 200 kg ha^-1, irrespective of placement. Emissions from pre-plant banding ESN at 200 kg ha^?1, however, were 32% lower than from PPI ESN. For Experiment 2, compared to single pre-plant urea application, fertigation simulated by in-season application of urea ammonium nitrate (UAN) gave lower area-, yield- and applied fertilizer N- based emissions. Split urea ( \( \raisebox{1ex}{$2$}\!\left/ \!\raisebox{-1ex}{$3$}\right. \) pre-plant, \( \raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$3$}\right. \) hilling) also reduced area- and yield- based N₂O emissions compared to single pre-plant urea application. Emissions were generally lower at the site with loamy fine sandy soil than the site with clay loam soil. These results demonstrate that combinations of “4R” practices rather than source alone are best to achieve reductions in N₂O emissions from irrigated potato production.     

The pelagic habitat analysis module for ecosystem‐based fisheries science and management

We have developed a set of tools that operate within an aquatic geographic information system to improve the accessibility, and usability of remote‐sensed satellite and computer‐modeled oceanographic data for marine science and ecosystem‐based management. The tools form the Pelagic Habitat Analysis Module (PHAM), which can be applied as a modeling platform, an investigative aid in scientific research, or utilized as a decision support system for marine ecological management. Applications include fisheries, marine biology, physical and biological oceanography, and marine spatial management. The GIS provides a home for diverse data types and automated tools for downloading remote sensed and global circulation model data. Within the GIS environment, PHAM provides a framework for seamless interactive four‐dimensional visualization, for matching between disparate data types, for flexible statistic or mechanistic model development, and for dynamic application of user developed models for habitat, density, and probability predictions. Here we describe PHAM in the context of ecosystem‐based fisheries management, and present results from case study projects which guided development. In the first, an analysis of the purse seine fishery for tropical tuna in the eastern Pacific Ocean revealed oceanographic drivers of the catch distribution and the influence of climate‐driven circulation patterns on the location of fishing grounds. To support management of the Common Thresher Shark (Alopias vulpinus) in the California Current Ecosystem, a simple empirical habitat utilization model was developed and used to dynamically predict the seasonal range expansion of common thresher shark based on oceanographic conditions.     

Crop structure in winter oats and the effect of nitrogen on quality-related characters

The relationship between panicle structure and oat grain quality characteristics was examined in a winter oat (Avena sativa) experiment, cv. Gerald, fertilized with 80 and 200 kg/ha N. Spikelets on each whorl were counted and separated into primary, secondary, and tertiary grains, which were counted and weighed, and the kernels extracted manually and weighed. Tiller and whorl rank had relatively small effects on weight per grain and kernel content. Nitrogen application significantly increased weight per primary and secondary grain on the main stem and T1, the first tiller, while spikelet and grain numbers increased only on T1. However, weight per grain and kernel contents in all whorls on both the main stem and T1 were not significantly affected by nitrogen. Although kernel contents were significantly affected by nitrogen application on some occasions, increases and decreases were less than 2.5%. Across the whole plant, numbers of primary and secondary grains increased at the higher nitrogen application, but weight per primary grain and kernel contents were unaffected. However, weight per secondary grain significantly increased at the higher nitrogen application, thus improving uniformity of grain size which is of value to millers.     

Geographic variation in host fish use and larval metamorphosis for the endangered dwarf wedgemussel

1. Host fishes play a crucial role in survival and dispersal of freshwater mussels (Unionoida), particularly rare unionids at conservation risk. Intraspecific variation in host use is not well understood for many mussels, including the endangered dwarf wedgemussel (Alasmidonta heterodon) in the USA.
2. Host suitability of 33 fish species for dwarf wedgemussel glochidia (larvae) from the Delaware and Connecticut river basins was tested in laboratory experiments over 9 years. Relative suitability of three different populations of a single host fish, the tessellated darter (Etheostoma olmstedi), from locations in the Connecticut, Delaware, and Susquehanna river basins, was also tested.
3. Connecticut River basin A. heterodon metamorphosed into juvenile mussels on tessellated darter, slimy sculpin (Cottus cognatus), and Atlantic salmon (Salmo salar) parr. Delaware River basin mussels metamorphosed using these three species, as well as brown trout (Salmo trutta), banded killifish (Fundulus diaphanus), mottled sculpin (Cottus bairdii), striped bass (Morone saxatilis), and shield darter (Percina peltata). Atlantic salmon, striped bass, and sculpins were highly effective hosts, frequently generating 5+ juveniles per fish (JPF) and metamorphosis success (MS; proportion of attaching larvae that successfully metamorphose) ≥ 0.4, and producing juveniles in repeated trials.
4. In experiments on tessellated darters, mean JPF and MS values decreased as isolation between the mussel source (Connecticut River) and each fish source increased; mean JPF = 10.45, 6.85, 4.14, and mean MS = 0.50, 0.41, and 0.34 in Connecticut, Delaware, and Susquehanna river darters, respectively. Host suitability of individual darters was highly variable (JPF = 2–11; MS = 0.20–1.0).
5. The results show that mussel–host fish compatibility in A. heterodon differs among Atlantic coastal rivers, and suggest that hosts including anadromous Atlantic salmon and striped bass may help sustain A. heterodon in parts of its range. Continued examination of host use variation, migratory host roles, and mussel–fish interactions in the wild is critical in conservation of A. heterodon and other vulnerable mussel species.

     

Effect of fish meal replacement with Carinata Brassica carinata in low animal protein diets of rainbow trout Oncorhynchus mykiss (Walbaum) on trypsin activity,protein and amino acid digestibility and bioavailability

Replacement of >25% of fish meal (FM) with aerobically converted carinata meal (ACCM) in low (200g/kg) animal protein (reference = 200g/kg FM) diets of rainbow trout Oncorhynchus mykiss resulted in reduced growth, partly due to reduced feed consumption and protein utilization. In this study, we determined the effect of FM replacement with ACCM on trypsin activity, apparent digestibility coefficients (ADCs) of protein, and essential amino acid (EAA) or conditionally essential amino acid (CEAA) ADCs and bioavailability. Replacement of FM did not alter protein ADCs or trypsin activity. Replacement of >25% FM reduced all EAA and CEAA ADCs except for arginine and leucine which were only reduced by 75% FM replacement. Only serum free lysine and muscle free histidine were reduced by >25% FM replacement. Muscle free lysine was only reduced by 75% FM replacement. Replacement of FM reduced EAA peak concentrations and resulted in slower release of EAAs in serum. Cumulative total EAAs in serum and muscle decreased with FM replacement. Ratios of EAAs to lysine showed that tryptophan was the most limiting EAA. However, isoleucine, leucine, methionine and phenylalanine were also inadequate for muscle synthesis for the first 9–12 hr following force‐feeding. Optimal time for protein synthesis was ≥36 hr. Although any level of FM replacement did not reduce protein ADCs and trypsin activity, replacement of ≥25% FM reduced EAA ADCs and bioavailability of lysine and histidine, which partly contributed to the observed differences in growth.     

The effects of exogenous xylanase supplementation on the in vivo generation of xylooligosaccharides and monosaccharides in broilers fed a wheat-based diet

ABSTRACT

1. This study quantified xylanase-induced changes in soluble monosaccharides, xylooligosaccharides (XOS) and volatile fatty acid (VFA) contents of the different sections of the gastrointestinal tract (GIT) and whether these were related to altered bird performance.

2. An in vitro digestion of the wheat-based diet was carried out with the xylanase (Econase XT at 16,000BXU/kg diet) to compare the in vitro and in vivo generation of these XOS and monosaccharides. For the in vivo study, 80 male Ross 508 b roiler chicks were split into two groups fed a wheat-based diet with or without Econase XT (16,000BXU/kg diet) for 21 days.

3. There were no effects of Econase XT inclusion on growth performance characteristics, likely a result of the high-quality wheat diet, the corresponding high performance of the control group (FCR average of 1.45 in controls) and the relatively young age of the birds (from four to 26 days of age).

4. Econase XT supplementation increased the xylotetraose (X₄) content in the colon (P = 0.046, enzyme x GIT section interaction) and the xylose contents in the colon and caeca (P < 0.001, enzyme x GIT section interaction).

5. The trend for increased acetate production in the caeca of Econase XT treated birds (P = 0.062) suggested that the XOS generated were subsequently fermented in the caeca, potentially impacting upon the types of microbiota present.

6. The present study suggested that wheat arabinoxylan degradation was enhanced by xylanase supplementation, which may have increased the production of beneficial volatile fatty acids (VFA) in the caeca, and thereby potentially modulated the caecal microbiome, but without affecting bird performance at this early age.     

Zoonotic Helminths of Urban Brown Rats (Rattus norvegicus) in the UK: Neglected Public Health Considerations?

Urban brown rats (Rattus norvegicus) carry microbial human pathogens but their role as reservoir hosts for helminths of public health importance is less well known. In this study, 42 brown rats trapped on Merseyside were subject to thorough combined helminthological and pathohistological post‐mortem examination. Eggs of the rodent‐borne zoonotic nematode Calodium hepaticum were initially detected in histological sections of the livers of 9.5% of rats, but overall diagnostic sensitivity increased to 16.6% when entire liver tissue was disrupted and the resulting filtrates were examined for released eggs. In their rat host, mainly trapped inside the dockland, infections with C. hepaticum were associated with a chronic multifocal pyogranulomatous hepatitis with intralesional eggs and peripheral fibrosis. Mean intensity of hepatic C. hepaticum egg infections was 1041 eggs. This is the first report of C. hepaticum in an urban brown rat population in the UK and provides original data for liver egg burdens in this abundant commensal rodent. The zoonotic cestode Rodentolepis nana had a prevalence of infection of 14.3%. Rodent‐specific, non‐zoonotic helminths found were the spiruroid Mastophorus muris (16.0%) in the stomach, the trichuroid Trichosomoides crassicauda in the urinary bladder (31.0%); the ascarid Heterakis spumosa was the commonest helminth of the large intestine (76.2%). Many millions of brown rats inhabit cities and rural areas of the UK, and the infective stages of the zoonotic worm species, particularly C. hepaticum, are likely to be widely distributed in the environment presenting a threat to public health.     

A diagnostic approach to the pruritic horse

Pruritus is a common complaint in equine medicine. While pruritus in most horses is due to ectoparasites (midges, flies, mites) or environmental allergens (pollens, barn dust, moulds, etc.), other causes such as staphylococcal or fungal infections, vasculitis, and internal organ dysfunction should not be overlooked. In a rational approach to the pruritic horse, history and physical examination become very important as a guide to choosing diagnostic tests.