Plants control the seasonal dynamics of microbial N cycling in a beech forest soil by belowground C allocation

Soil microbes in temperate forest ecosystems are able to cycle several hundreds of kilograms of N per hectare per year and are therefore of paramount importance for N retention. Belowground C allocation by trees is an important driver of seasonal microbial dynamics and may thus directly affect N transformation processes over the course of the year. Our study aimed at unraveling plant controls on soil N cycling in a temperate beech forest at a high temporal resolution over a time period of two years, by investigating the effects of tree girdling on microbial N turnover. In both years of the experiment, we discovered (1) a summer N mineralization phase (between July and August) and (2) a winter N immobilization phase (November-February). The summer mineralization phase was characterized by a high N mineralization activity, low microbial N uptake, and a subsequent high N availability in the soil. During the autumn/winter N immobilization phase, gross N mineralization rates were low, and microbial N uptake exceeded microbial N mineralization, which led to high levels of N in the microbial biomass and low N availability in the soil. The observed immobilization phase during the winter may play a crucial role for ecosystem functioning, since it could protect dissolved N that is produced by autumn litter degradation from being lost from the ecosystem during the phase when plants are mostly inactive. The difference between microbial biomass N levels in winter and spring equals 38 kg N/ha and may thus account for almost one-third of the annual plant N demand. Tree girdling strongly affected annual N cycling: the winter N immobilization phase disappeared in girdled plots (microbial N uptake and microbial biomass N were significantly reduced, while the amount of available N in the soil solution was enhanced). This was correlated to a reduced fungal abundance in autumn in girdled plots. By releasing recently fixed photosynthates to the soil, plants may thus actively control the annual microbial N cycle. Tree belowground C allocation increases N accumulation in microorganisms during the winter which may ultimately feed back on plant N availability in the following growing season.     

How to toughen up your mussels: using mussel shell morphological plasticity to reduce predation losses

Improvements in stocking strategy and management could increase the yield of mussels that are on-grown from harvested wild seed mussel resources and thereby enhance the sustainability of this shellfishery. A field experiment was undertaken to ascertain shell characteristics (compression strength and thickness) of seed mussels grown at different shore heights, whether these characteristics changed after a period of growth under identical conditions, and if these characteristics reduced predation losses by crabs and birds. Results indicated that mussels grown at higher shore levels attained shell characteristics beneficial to predation resistance and that these were maintained after a period of growth at a lower shore level. A novel management plan for mussel cultivation was formulated from the results of this study by manipulating shore position according to the attainment of these predator resistant shell attributes and the spatial distribution of the main natural mussel predators (crabs and birds). This technique was expanded to address the mussel cultivation problem of low natural seed settlement.     

Investigation of odors in the fragrance industry

Scents form the basis for the fragrance industry and various research activities have been developed in different scientific disciplines all being linked by a common interest in odors and odor perception. In this paper, four different topics have been selected for a short discussion. Following a short overview on the history of perfumery, the first topic (Natural scents) is providing some insight into the investigation of natural scents and how this work has strongly stimulated fragrance creation as well as the quest to find new odoriferous substances for the perfumer’s palette. The second subject (Fragrance chemistry) gives a historical overview over the chemistry of fragrances and briefly describes the rational behind the synthesis and composition of new scents. Body odors and their biochemical formation concern the third topic (Body odor biochemistry) which describes our current understanding of this scientifically interesting field and how knowledge may find use to improve future deodorant products. The fourth subject (Olfactory mechanisms) deals with the biochemistry in the human nose when odorants are activating olfactory receptors and enzymes appear to rapidly metabolize the inhaled odorous stimuli. This review does not attempt to be comprehensive, but it describes selected successes in the fragrance industry and the motivation behind conducting various types of research. Ultimately, the activities are aiming to bring new ingredients onto the market and improve the quality of scented products but also to advance our understanding of the power of communication through fragrance.     

Resilience and Challenges of Marine Social–Ecological Systems Under Complex and Interconnected Drivers

In this paper, we summarize the contributions made by an interdisciplinary group of researchers from different disciplines (biology, ecology, economics, and law) that deal with key dimensions of marine social–ecological systems. Particularly, the local and global seafood provision; the feasibility and management of marine protected areas; the use of marine ecosystem services; the institutional dimension in European fisheries, and the affordable models for providing scientific advice to small-scale fisheries. This Special Issue presents key findings from selected case studies around the world available to educators, policy makers, and the technical community. Together, these papers show that a range of diverse ecological, economic, social, and institutional components often mutually interact at spatial and temporal scales, which evidence that managing marine social–ecological systems needs a continuous adaptability to navigate into new governance systems.     

Effects of selected chemicals to photoluminescent bacteria and their correlations with acute and sublethal effects on other organisms

Microtox^R1 test toxicity values for twenty chlorophenols, twelve chlorobenzenes and thirteen para-substituted phenols have been determined and correlated with the acute and sublethal effects of these chemicals on several species of fish, bacteria and shrimp. The results indicate that the Microtox^R test provides good estimates of the toxicities to the various biota, as shown by the linear correlation equations presented, and that it is useful for the calculation of structure-activity correlations with physico-chemical parameters, such as the octanol/water partition coefficient.