Onchocerca sp. in an imported Zangersheide gelding causing suspensory ligament desmitis

A 5-year-old imported Zangersheide gelding was evaluated for SC swellings over both forelimbs and lameness localized to the distal metacarpus. Ultrasound examination of the SC masses was compatible with verminous granulomas. Linear hyperechoic foci were present within the suspensory ligament branches of both forelimbs, suggestive of ligamentous parasitic infiltrates. A diagnosis of onchocerciasis was confirmed on biopsy of a SC mass. The gelding was treated with ivermectin and a tapering course of PO dexamethasone but was eventually euthanized. Necropsy confirmed the presence of SC eosinophilic granulomas and degenerative suspensory ligament desmitis, both with intralesional nematodes. Given the location and appearance of the nematode, a diagnosis of Onchocerca sp., most likely O. reticulata, was made. Onchocerciasis should be included as a differential diagnosis for multifocal suspensory ligament desmitis with these sonographic characteristics when paired with SC masses in imported European Warmbloods.     

Farmer's perspective on irrigation performance

Of the many client groups with interests in irrigation system performance, farmers are probably the least often considered. This paper attempts to explore the meaning of irrigation performance from their perspective, highlighting at the outset basic difference between this perspective and that of system managers. It then reviews several important concepts underlying a consideration of performance in irrigation systems. The paper then proposes and discusses a set of twelve measures of irrigation service judged to be of interest to farmers. These are adequacy, timeliness, equity, tractability, convenience, predictability, temperature, sediment content, salt content, nutrient content, toxics, and pathogens.     

Irrigation and food security in the 21st century

Global food projections indicate that food prices in the next threedecades will likely be stable or decline, but progress inreducing malnutrition in developing countries will be slow. Smallshortfalls in crop productivity growth would lead to rising foodprices and worsening malnutrition. Increased food production fromirrigation is essential, and will require expansion of irrigatedarea and water supplies, and improved efficiency of use of existingwater supplies. Neither of these growth factors will prove easy, andboth will require complex institutional and policy reforms. Failureto meet food production needs through efficient expansion andintensification of irrigated agriculture would increase pressure onland resources and hasten the process of environmental degradation.Irrigation and water development strategies have been hampered bya lack of understanding of the links between water scarcity, foodproduction, food security, and environmental sustainability.Research to improve this understanding would have high payoffs.     

Creating and Consolidating Locally Managed Irrigation in Turkey: the National Perspective

The Turkish program of irrigationmanagement transfer has gained worldwidecelebrity for its speed and effectiveness. This paper describes the program brieflyand assesses its effectiveness from anational perspective. The assessmentincludes changes in staffing levels,operational costs, service fee levels, andcost recovery from farmers. A companionpaper examines impacts at the local leveland looks specifically at changes in systemperformance.     

Habitat suitability and connectivity modeling reveal priority areas for Indiana bat (Myotis sodalis) conservation in a complex habitat mosaic

Context

Conservation for the Indiana bat (Myotis sodalis), a federally endangered species in the United States of America, is typically focused on local maternity sites; however, the species is a regional migrant, interacting with the environment at multiple spatial scales. Hierarchical levels of management may be necessary, but we have limited knowledge of landscape-level ecology, distribution, and connectivity of suitable areas in complex landscapes.

Objectives

We sought to (1) identify factors influencing M. sodalis maternity colony distribution in a mosaic landscape, (2) map suitable maternity habitat, and (3) quantify connectivity importance of patches to direct conservation action.

Methods

Using 3 decades of occurrence data, we tested a priori, hypothesis-driven habitat suitability models. We mapped suitable areas and quantified connectivity importance of habitat patches with probabilistic habitat availability metrics.

Results

Factors improving landscape-scale suitability included limited agriculture, more forest cover, forest edge, proximity to medium-sized water bodies, lower elevations, and limited urban development. Areas closer to hibernacula and rivers were suitable. Binary maps showed that 30% of the study area was suitable for M. sodalis and 29% was important for connectivity. Most suitable patches were important for intra-patch connectivity and far fewer contributed to inter-patch connectivity.

Conclusions

While simple models may be effective for small, homogenous landscapes, complex models are needed to explain habitat suitability in large, mixed landscapes. Suitability modeling identified factors that made sites attractive as maternity areas. Connectivity analysis improved our understanding of important areas for bats and prioritized areas to target for restoration.

     

Effects of cover crop quality and quantity on nematode-based soil food webs and nutrient cycling

Soil food webs cycle nutrients and regulate parasites and pathogens, services essential for both agricultural productivity and ecosystem health. Nematodes provide useful indicators of soil food web dynamics. This study was conducted to determine if nematode soil food web indicators and crop yield can be enhanced by combinations of cover crops in a conservation tillage system. The effects of three cover crop treatments (vetch/pea, oat/wheat and oat/wheat/pea/vetch) with low, medium and high C:N and a bare fallow control were investigated in Davis, CA. Nematode fauna, soil properties and plant productivity were measured. Soil food web indices, including the Enrichment Index (EI), Structure Index (SI), Basal Index (BI), and Channel Index (CI), based on the composition of nematode assemblages, were calculated to infer soil food web condition. Cover cropped tomato/corn rotations had twice the number of enrichment opportunist bacterial feeding nematodes, active participants in nitrogen mineralization, than fallowed tomato/corn rotations (opportunist bacterial feeders = 163 versus 98). In winter fallowed plots food webs were basal, common in disturbed, nutrient-poor conditions (BI = 37). Total number of enrichment opportunist nematodes, soil NH₄-N levels, and inferred nitrogen mineralization, were higher in cover crop treatments with low to mid C:N ratios. Omnivore and predator nematodes were scarce, averaging less than 6 nematodes 100 g^?1 in all treatments. In year one, plant productivity was highest after fallow. In contrast, in year two productivity was highest after cover crops with high nitrogen content and productivity significantly correlated with the structure of the soil fauna. Monitoring the abundance of enrichment opportunists may provide managers with a new tool to evaluate soil food web nitrogen mineralization and plant productivity.     

The source of autumn and spring downstream migrating juvenile Atlantic salmon in a small lowland river

Over 3 years, 32,444 age‐0 group Atlantic salmon (Salmo salar) parr tagged with passive integrated transponder tags throughout the River Frome catchment were assigned to one of three groups, nonmigrants, autumn migrants and spring smolts, depending on the detection and the timing of detection at downstream tag readers (situated 8.6 km above the tidal limit). We examined the effect of density at the time of tagging (n·m^?2), distance upstream from the tidal limit (km), fish length (mm), Fulton condition index, habitat type (divided into two types, main river and carrier), days after 1 September that each fish was tagged and year (replication) on the proportions of fish in each of the migration groups. Distance upstream from tidal limit was strongly negatively related to the proportion of autumn migrants and positively related to the proportion of spring smolts. Nonmigrants had a lower average body size than migrants, although there were no differences in the sizes of autumn migrants and spring smolts in September prior to migration. Fish density had no effect on migration strategy. A lower proportion of fish migrated as autumn migrants from the smaller carrier habitats than the main river channel. There is some evidence that those parr destined to become autumn migrants underwent a lower mortality rate during September before tagging than those destined to become spring migrants indicating possible physiological or behavioural differences between these two groups of fish at that time. More research into the factors responsible for initiating the autumn migration is required.