Management of the Spring Snowmelt Recession in Regulated Systems

In an effort to restore predictable ecologically relevant spring snowmelt recession flow patterns in rivers regulated by dams, this study defined a methodology by which spring flow regimes can be modeled in regulated systems from the quantifiable characteristics of spring snowmelt recessions in unregulated rivers. An analysis of eight unregulated rivers across the Sierra Nevada mountain range in California found that unregulated systems behaved similarly with respect to seasonal spring patterns and recession limb curvature, and thus prescribed flows could be designed in a manner that mimics those predictable characteristics. Using the methodology to quantify spring recession flows in terms of a daily percent decrease in flow, a series of flow recession scenarios were created for application in an existing hydrodynamic model for the regulated Rubicon River. The modeling results showed that flow recessions with slow ramping rates similar to those observed in unregulated rivers (less than 10% per day) were likely to be protective of native aquatic species, such as the Foothill yellow‐legged frog, while flows that receded at greater rates would likely result in desiccation of egg masses and potential stranding of tadpoles and fry. Furthermore, recession rates of less than 10% per day provided the most spatially diverse hydraulic habitat in the modeled domain for an appropriate duration in spring to support all native species guilds and maximize aquatic biodiversity.     

Reduced take-off ability in robins (Erithacus rubecula) due to migratory fuel load

Recent studies have shown that large fuel loads in small birds impair flying ability. This is the first study to show how migratory fuel load affects flying ability, such as velocity and height gained at take-off in a predator escape situation, in a medium-distance migrant, and whether they adjust their take-off according to predator attack angle. First-year robins (Erithacus rubecula) were subjected to simulated attacks from a model merlin (Falco columbarius), and take-off velocity and angle were analysed. Robins with a wing load of 0.19 g cm⁻² took off at a 39% lower angle than robins with a wing load of 0.13 g cm⁻², while velocity remained unaffected. The robins did not adjust their angle of ascent in accordance with the predator's angle of attack. Since many predators rely on surprise attacks, a difference in flight ability due to varying fuel loads found in migrating robins can be important for birds' chances of survival when actually attacked. Received: 28 October 1998 / Received in revised form: 12 January 1999 / Accepted: 30 January 1999     

Quality assessment of composts in the Greek market: the need for standards and quality assurance

An extensive data survey and study of the Greek market for composts or products marketed as such was carried out in order to acquire a comprehensive image of the local situation, in view of the proposed operation of large municipal solid waste (MSW) composting facilities and EU legislation changes. Physical and chemical parameters (moisture, organic matter, electrical conductivity, pH and heavy metals), stability indicators (self-heating potential, germination index) and biological indicators (microbial population, pathogen indicators and selected pathogens) were analyzed for the assessment of product quality. Results revealed wide variations even within the same group of products, which is particularly significant for parameters directly related to environmental protection and public health. The heavy metal content ranged from levels exceeding the fairly lenient Greek standards to below the stringent limits for A+ class compost in Austria. About 25% of the composts examined met the heavy metal limits for the EU eco-label award. Salmonella spp. was not detected in any of the composts but Staphylococcus aureus and Clostridium perfringens were found in 17 and 96% of the composts respectively. Pathogen indicator microorganisms were present at levels above suggested limits in all the composts. The high variability of such important parameters in composts available on the Greek market suggests an urgent need for establishing quality assurance procedures and mechanisms in the country. Moreover, the wide range of limit values within EU member states suggests the need for developing EU compost quality standards, in order to harmonize the compost markets.     

Microbial characterization during composting of biowaste

Windrow composting of source-separated biowaste was studied in a pilot plant in Crete, with regard to abiotic factors, gas concentration in the pile and succession of functional microbial groups. The pH, C/N ratio and VS content, as well as the O₂ and CO₂ concentration, correlated well with composting time, indicating typical composting behaviour. Most of the microbial groups examined exhibited their highest counts towards the end of the thermophilic phase, with declining trends thereafter. The population of total mesophilic and thermophilic bacteria increased during the mild thermophilic phase and followed the temperature decline thereafter. Results on these microbial groups and fungi indicate that the timing of the thermophilic stage in the composting process, in addition to the peak temperature and duration of the stage, affects the microbial succession. Escherichia coli were detected for over 2 months of processing, in spite of the high temperatures achieved; only after about 3 months of composting did its population decline below the detection limit.     

Norovirus GII.17 Outbreak Linked to an Infected Post-Symptomatic Food Worker in a French Military Unit Located in France

In February 2016, an outbreak of gastroenteritis occurred in a French military unit located in Poitiers, France. Attack rate was of 34% (103/300). A case–control study identified association between illness and cake consumption. Stool samples were tested positive for Norovirus GII.17 for one patient and one post-symptomatic food worker (FW). The FW presented vomiting one day before cake preparation. The NoV strain was probably spread through food worker hand contact. Prevention of Norovirus foodborne outbreaks implies new guidelines for FWs management in France and Europe.     

Differences in olfactory sensitivity and behavioral responses among honey bees bred for hygienic behavior

Honey bees, Apis mellifera L., bred for hygienic behavior uncap and remove diseased and mite-infested brood. We hypothesized that within a colony bred for hygienic behavior, there would be differences in olfactory sensitivity among bees of the same age. We predicted that bees that initiate the behavior by perforating and uncapping brood would have greater olfactory sensitivity to the odor of the diseased brood, and would be better able to discriminate between odors of healthy and diseased brood, compared to bees that complete the behavior by removing the uncapped brood from the cells. Electroantennogram recordings of 15- to 21-day-old bees from three colonies demonstrated that bees collected while uncapping dead brood had significantly greater olfactory sensitivity to all concentrations of diseased brood odor compared to bees collected while removing brood. Proboscis-extension reflex discrimination conditioning demonstrated that 15- to 21-day-old bees collected while uncapping discriminated significantly better and generalized significantly less between the odors of diseased and healthy brood compared to bees collected while removing, when the odor of diseased brood was rewarded, but not when the odor of healthy brood was rewarded. Bees collected while uncapping brood that had been pierced with a pin had significantly less olfactory sensitivity than bees collected while uncapping freeze-killed brood, most likely because the pierced brood had greater stimulus intensity. Initiation of hygienic behavior depends on the olfactory sensitivity of the bee and stimulus intensity of the abnormal brood. Differential olfactory sensitivity and responsiveness among hygienic bees could lead to the apparent partitioning of the behavior into uncapping and removing components.Communicated by R.F.A. Moritz     

Using the negative binomial distribution to model overdispersion in ecological count data

A Poisson process is a commonly used starting point for modeling stochastic variation of ecological count data around a theoretical expectation. However, data typically show more variation than implied by the Poisson distribution. Such overdispersion is often accounted for by using models with different assumptions about how the variance changes with the expectation. The choice of these assumptions can naturally have apparent consequences for statistical inference. We propose a parameterization of the negative binomial distribution, where two overdispersion parameters are introduced to allow for various quadratic mean-variance relationships, including the ones assumed in the most commonly used approaches. Using bird migration as an example, we present hypothetical scenarios on how overdispersion can arise due to sampling, flocking behavior or aggregation, environmental variability, or combinations of these factors. For all considered scenarios, mean-variance relationships can be appropriately described by the negative binomial distribution with two overdispersion parameters. To illustrate, we apply the model to empirical migration data with a high level of overdispersion, gaining clearly different model fits with different assumptions about mean-variance relationships. The proposed framework can be a useful approximation for modeling marginal distributions of independent count data in likelihood-based analyses.