Sources of organic matter for intertidal consumers on Ascophyllum-shores (SW Iceland): a multi-stable isotope approach

Stable isotopes were used to examine the origin of organic matter in Icelandic Ascophyllum-based habitats, the role of different organic matters in filling intertidal food webs and the food preferences of the most abundant suspension feeders, grazers and predators. We selected three intertidal sites on the SW coast of Iceland where we sampled in early September 2004, organic matter sources (POM, SOM and most abundant primary producers, A. nodosum and F. vesciculosus) and the most abundant macrofauna species (barnacles, mussels, gastropods, sponge and crabs). Even though the primary production (Ascophyllum-based) was the same at the three study sites, the isotopic composition of common-among-sites organisms varied due to local differences in the origin of available POM and SOM and in food web structures.     

Application of a Multi-Criteria Decision-Making Approach for Ranking Environmental Risks Caused by Petrochemical Industries: A Case Study of a Sodium Carbonate Production Unit

The occurrence of accidents in petrochemical industries that cause environmental catastrophes has persuaded experts to use risk-oriented approaches. The approach is to rank the key elements of risk assessment by which the priority of each risk is specified compared to the other ones. The present study was performed to test the applicability of a multi-criteria decision-making approach for prioritizing environmental risks of a petrochemical complex in southwestern Iran. Accordingly, all risky activities of the Sodium Carbonate Production Unit (SCPU) were identified initially. Afterward, the relevant environmental components affected by the risky activities were specified. According to the specification, the most significant risks were shortlisted using experts’ judgment based on three criteria: “impact intensity,” “occurrence probability,” and the “extent of contamination dispersion in the environment.” The shortlisted environmental risks were then prioritized by the Method “Elimination et Choice Translating Reality (Elimination and Choice Expressing Reality)” abbreviated as ELECTRE. Based on the obtained results, “decreased air quality” and “manpower health threatening” are the top-priority risks while “poor quality of groundwater” was identified as the least priority risk. In a general conclusion, a multi-criteria decision-making approach is quite useful for assessing environmental risks of petrochemical industries.     

Influences of extreme weather,climate and pesticide use on invertebrates in cereal fields over 42 years

Cereal fields are central to balancing food production and environmental health in the face of climate change. Within them, invertebrates provide key ecosystem services. Using 42 years of monitoring data collected in southern England, we investigated the sensitivity and resilience of invertebrates in cereal fields to extreme weather events and examined the effect of long‐term changes in temperature, rainfall and pesticide use on invertebrate abundance. Of the 26 invertebrate groups examined, eleven proved sensitive to extreme weather events. Average abundance increased in hot/dry years and decreased in cold/wet years for Araneae, Cicadellidae, adult Heteroptera, Thysanoptera, Braconidae, Enicmus and Lathridiidae. The average abundance of Delphacidae, Cryptophagidae and Mycetophilidae increased in both hot/dry and cold/wet years relative to other years. The abundance of all 10 groups usually returned to their long‐term trend within a year after the extreme event. For five of them, sensitivity to cold/wet events was lowest (translating into higher abundances) at locations with a westerly aspect. Some long‐term trends in invertebrate abundance correlated with temperature and rainfall, indicating that climate change may affect them. However, pesticide use was more important in explaining the trends, suggesting that reduced pesticide use would mitigate the effects of climate change.     

Interactions between genotype and sexual conflict environment influence transgenerational fitness in Drosophila melanogaster

Theory predicts that sexual conflict can fuel evolutionary change and generate substantial reproductive costs. This was tested here by measuring the fitness of focal individuals across multiple generations using an experimental framework. We manipulated sexual conflict through high versus low exposure of females to males across a four-generation pedigree of Drosophila melanogaster, and assessed fitness in 1062 females and 639 males. We used the animal model to estimate (1) genotype by sexual conflict environment interactions for female fitness and (2) indirect benefits gained through sons and daughters. Some female genotypes achieved higher fitness under low, in comparison to high, conflict and vice versa. We found a consistent 10% reduction in female fitness under high conflict, regardless of maternal history. Following high exposure, females produced sons with increased, but grandsons with decreased, fitness. This opposing effect suggests no consistent fitness gains through sons for females that mated multiply. We saw no indirect benefits through daughters. Our pedigree was based exclusively on maternal links; however, maternal effects are unlikely to contribute significantly unless expressed across multiple generations. In sum, we quantified a significant sexual conflict load and a female genotype by sexual conflict interaction that could slow the erosion of genetic variation.     

Recovery of E. coli O157 strains after exposure to acidification at pH 2

Aims: Rapid detection and selective isolation of E. coli O157:H7 strains have been difficult owing to the potential interference from background microflora present in high background food matrices. To help selectively isolate E. coli O157H7 strains, a useful plating technique that involved acidifying the cultures to pH 2 was evaluated with a large number of E. coli O157:H7 strains to ensure response to treatment was consistent across strains. Methods and Results: Escherichia coli O157, 46 strains including ATCC 35150, were acidified to pH 2 following enrichment and plated onto Tryptic Soy Agar + 0·6% Yeast Extract (TSA‐YE) and Sorbitol MacConkey Agar + cefixime and tellurite (CT‐SMAC). Samples were enumerated and modest decreases in plate counts were observed on TSA‐YE media, with a greater reduction observed on CT‐SMAC. Conclusions: The acid‐resistant character of E. coli O157:H7 is a consistent trait and may be used for improved isolation of the organism from mixed cultures. Significance and Impact of the Study: There was little difference observed between the commonly used laboratory strain E. coli O157:H7 35150 and 45 other strains of E. coli O157 when subjected to acidifying conditions prior to plating, demonstrating that an acid rinse procedure was equally effective across a wide variety of E. coli O157 strains and broadly applicable for isolating unknown strains from food samples.     

UV‐absorbing films and nets affect the dispersal of western flower thrips,Frankliniella occidentalis (Thysanoptera: Thripidae)

UV‐absorbing films and nets are frequently used as covering materials for netted greenhouses and film tunnels in protected cultivation systems. This study explored the effects of such materials on the dispersal behaviour of western flower thrips (WFT), Frankliniella occidentalis, in flight cages under greenhouse conditions with additional artificial UV‐A light sources. The study involved release–recapture experiments in choice and no‐choice layouts. Different trapping methods were compared (blue sticky cards, plants and transparent cards) for recapture of thrips. In choice experiments, insects were released from a black box compartment between two tunnels covered with either UV‐transmitting or UV‐absorbing materials. A significantly higher proportion of (82–98%) WFT was recaptured in UV‐transmitting tunnels compared with UV‐absorbing tunnels. In no‐choice experiments, WFT were found to infiltrate the tunnels at different rates depending on the trap type used and experimental layout. In small‐scale dispersal experiments using blue sticky cards and plants as traps, infiltration was not significantly different between UV‐absorbing and UV‐transmitting tunnels, whereas when using transparent cards, WFT penetrated further into the UV‐transmitting plastic film tunnels. In larger‐scale dispersal experiments, plants or blue sticky cards were arranged in concentric circles around a source plant at the release point. Dispersal was found to differ depending on the method of release, but WFT tended to exhibit reduced dispersal from source plants under UV‐deficient conditions. In conclusion, our data support the hypothesis that manipulation of spectral light properties using UV‐absorbing cladding materials for protected crop stands interferes with the orientation and host finding of WFT, resulting in reduced dispersal into and within plant stands in UV‐deficient environments.     

Evolutionary Assurance vs. Mixed Mating

Reproductive assurance is a widely accepted explanation for the evolution of selfing, although theory suggests that an evolutionarily stable mixed mating strategy does not maximize seed production. We present a correlation analysis involving 28 species representing 23 families showing that selfing can evolve independently of inbreeding depression. We discuss the cost-benefit trade-off of selfing, in particular the incongruence of whether delayed selfing provides reproductive assurance in 22 species representing 14 families, in which pollen and seed discounting are minimized when pollinators or mates are scarce. Reproductive assurance, in response to frequent pollinator failure, can be reconciled with an evolutionarily stable mixed mating system contributed to by delayed selfing, which is still advantageous even if there is strong inbreeding depression.