Modelling the effects of litter decomposition on tree diversity patterns

Current theories may not fully explain why latitudinal patterns of plant diversity differ between terrestrial and flooded ecosystems. Moreover, the co-occurrence of hyper diverse stands in lowland tierra firma (not inundated) forests and almost monospecific stands in mangroves and gallery riparian vegetation within the tropics remains enigmatic. Building on evidence from ecology and agriculture, we present a new model investigating the hypothesis that, besides the general positive feedback of plant growth by nutrients release, litter decomposition builds up an intra-specific negative feedback functionally linked with tree diversity. The model results were compared with extensive published data sets both across and within latitudinal zones. The model predicts correctly the biomass production and decomposition process, as well as the number of tree species, their relative abundance in all environmental conditions providing a novel, putative explanation also for the diversity variations observed within the tropics. The model demonstrates a possible mechanistic link between the carbon cycle and biodiversity patterns, which is interesting in the debate about advancing in the direction of a unifying ecosystem theory.     

Diving costs and benefits during post-breeding movements of the Mediterranean shag in the North Adriatic Sea

From the 1980s, Mediterranean shags Phalacrocorax aristotelis desmarestii have become regular summer visitors in the Gulf of Trieste (N-E Italy), as post-breeding movements from Croatian breeding colonies. To characterize such a recent habit and to explore diving optimality models, we investigate foraging strategies and diving patterns at different depths, during breeding and post-breeding seasons. Behavioural data were cross-checked with the species’ diet. Shags foraged on and close to the sea bed, with a prevalent anticipatory breathing strategy. In the Gulf of Trieste, the shallow depths and low mobility of prey allowed shags to use just the oxygen of the respiratory tract, reducing the physiological stress for diving. In Croatia, dive costs increased with depth and prey mobility, resulting in a higher oxygen expenditure that involved also respiratory stores. Such ecological and physiological aspects characterize the Gulf of Trieste as an optimal area for feeding and restoring from the costs of breeding season incurred in Croatia and could be the basis of these post-breeding movements.     

Kinetics of the chemical degradation of diuron

The influence of pH and buffer concentration on the chemical degradation of diuron in water has been analysed over a wide temperature range. The process irreversibly gives 3,4-dichloroaniline as the only product containing the phenyl ring. H+, OH- and phosphate buffer are efficient catalysts of the reaction. The rate constant first increases rapidly at low buffer concentrations and then gradually levels off at higher ones. At 40 degrees C and high phosphate concentration (>0.01 M), or in the extreme pH regions, the half-life is approximately 4 months and the activation energy is 127 +/- 2 kJmol(-1).     

Biodiversity of epiphytic lichens and air pollution in the town of Siena (central Italy).

The results of a biomonitoring survey carried out in the town of Siena (central Italy) using the biodiversity of epiphytic lichens as indicator of air pollution are reported. The general picture was rather good, with more than 60% of the study area being in the categories "semi-natural" or "natural" according to a calibrated scale of environmental naturality/alteration. Compared with the situation of 1995, ameliorating conditions were found as a result of an improvement in air quality over time.     

Chemical speciation of carbon in municipal solid waste incinerator residues

Incinerators do not achieve a complete mineralization of organic constituents of municipal solid waste. The solid residues (bottom ash, boiler ash and air pollution control residues) contain carbon which can be determined as total organic carbon (TOC). This work focuses on the TOC composition and its significance to the genesis and diagenesis of the solid residues. An analytical procedure is presented to characterize carbon species by different chemical and microscopic analytical methods. The procedure is based on two steps. In the first step a quantitative classification of TOC into four different carbon species (elemental carbon, water extractable organic carbon, dichloromethane extractable organic carbon and non extractable organic carbon) is performed to obtain a first survey of the TOC composition. Based on this survey a further characterization of individual carbon species is performed. The results of the qualitative and quantitative characterization of carbon species allow to postulate hypotheses on the influence of organic carbon on the long-term behavior of the solid residues.     

The response of Trissolcus basalis to footprint contact kairomones from Nezara viridula females is mediated by leaf epicuticular waxes

Chemical footprints left behind by true bugs are perceived as contact kairomones by scelionid egg parasitoids. Female wasps encountering a contaminated artificial substrate display a characteristic arrestment posture, holding the body motionless and antennating the surface. In the system Nezara viridula (L.) and its egg parasitoid Trissolcus basalis (Wollaston), previous studies have shown that the kairomone mediating such behavior is part of N. viridula’s cuticular hydrocarbons (CHC) and furthermore that the wasp’s ability to discriminate host male and female footprints is mainly based on the presence/absence of nonadecane (nC₁₉). In this study, the effect of epicuticular waxes of leaves of broad bean, Vicia faba, on wasp responses to footprints of N. viridula females were investigated. Approximately 20% of T. basalis females displayed an arrestment posture when released on the adaxial leaf surfaces of broad bean plants with intact wax layer and without host chemical contamination; whereas ∼70% of wasps displayed the arrestment posture when intact leaves were contaminated by host female footprints. Adaxial leaf surfaces of broad bean plants dewaxed with an aqueous solution of gum arabic and afterwards contaminated by N. viridula females induced arrestment responses in about 10% of female wasps; the same percentage of arrestment (10%) was observed when the wasps were released on leaves contaminated by host females and subsequently dewaxed. The side of the polymer film that was appressed to the leaf surface, peeled from the contaminated leaves, induced an arrestment posture in about 95% of observed wasps. Scanning electron microscopy (SEM) revealed that the epicuticular waxes occurred as a film densely crystallized as irregularly shaped platelets with spherical granules randomly distributed. These findings demonstrated that epicuticular waxes of broad bean leaves can mediate the foraging behavior of T. basalis females by absorbing contact kairomones of the host.     

Deep carbon degassing in the Matese massif chain (Southern Italy) inferred by geochemical and isotopic data

Environmental Science and Pollution Research - The Italian Apennines are among the most important sources of freshwater for several Italian regions. With evidences of deep CO2-rich fluids intruding...     

Norovirus Outbreaks on Commercial Cruise Ships: A Systematic Review and New Targets for the Public Health Agenda

Noroviruses are recognized as the leading cause of human acute viral gastroenteritis worldwide. The rate of outbreaks on cruise ships has grown significantly in recent years. Given the potentially harmful consequences of outbreaks for passengers and crewmembers and the subsequently high costs for cruise companies, disease outbreaks on cruise ships represent a serious public health issue. The aim of our study was to systematically review published studies related to Norovirus outbreaks on commercial cruise ships. We searched the PubMed and Scopus scientific databases. We included eligible studies published from January 1990 to July 2013 that were written in English and described infectious episodes involving at least two passengers and/or crewmembers on a commercial cruise ship. As a result, 15 studies and seven reviews met the inclusion criteria, describing a total of 127 outbreaks. The majority of the cases were reported in Europe and the USA, affecting <1 to 74 % of the embarked passengers. In the majority of the studies, stool samples and/or serum specimens from ill passengers were collected and tested for laboratory confirmation. Twelve studies reported that an ad-hoc questionnaire was administered. Fifteen studies investigated the possible source of infection which was contaminated food in the majority of cases. Our findings suggest a strong need for the monitoring and implementation of preventive measures in semi-closed communities, such as cruise ships. It would be advisable to strengthen all relevant initiatives in order to improve the detection of, response to and control of Norovirus outbreaks on cruise ships.