Evaluating impacts of forage fish abundance on marine predators

Forage fish—small, low trophic level, pelagic fish such as herrings, sardines, and anchovies—are important prey species in marine ecosystems and also support large commercial fisheries. In many parts of the world, forage fish fisheries are managed using precautionary principles that target catch limits below the maximum sustainable yield. However, there are increasing calls to further limit forage fish catch to safeguard their fish, seabird, and marine mammal predators. The effectiveness of these extra-precautionary regulations, which assume that increasing prey abundance increases predator productivity, are under debate. In this study, we used prey-linked population models to measure the influence of forage fish abundance on the population growth rates of 45 marine predator populations representing 32 fish, seabird, and mammal species from 5 regions around the world. We used simulated data to confirm the ability of the statistical model to accurately detect prey influences under varying levels of influence strength and process variability. Our results indicate that predator productivity was rarely influenced by the abundance of their forage fish prey. Only 6 predator populations (13% of the total) were positively influenced by increasing prey abundance and the model exhibited high power to detect prey influences when they existed. These results suggest that additional limitation of forage fish harvest to levels well below sustainable yields would rarely result in detectable increases in marine predator populations.     

Agricultural landscapes as multi-scale public good and the role of the Common Agricultural Policy

During the last 50 years, the Common Agricultural Policy (CAP) has impacted the evolution of European agricultural landscapes by driving changes in land use and farming practices. We propose a typology characterising the scales relevant for agricultural landscapes management and argue that action is required on three scales: (1) a landscape oriented management at the farm level; (2) the coordination of land managers’ actions at the landscape level; and (3) the conservation of the diversity of agricultural landscapes in the EU. We provide evidence that until now the CAP has mainly focused on the first scale. We also illustrate how agricultural policy could encourage coordinated actions at the landscape- and EU-scales. In particular, we propose policy instruments to coordinate actions of individual land owners (e.g. collective bonus in agro-environmental contracts or support to environmental cooperatives (scale 2)). We also analyse how the recognition and transposition of the European Landscape Convention could promote trans-frontier landscape cooperation in order, not only to conserve high-quality rural landscapes, but also to ensure the conservation of the diversity of EU landscapes (scale 3). This paper provides a knowledge base to support an integrated CAP design in the direction of improved landscape management, as an important component of the EU project towards more sustainable agriculture.     

The application of positive matrix factorization in the analysis, characterisation and detection of contaminated soils

Multivariate factor analytical techniques are widely used for the approximation, in terms of a linear combination of factors, of multivariate experimental data. The chemical composition of soil samples are multivariate in nature and provide datasets suitable for the application of these statistical techniques. Recent developments of multivariate factor analytical techniques have led to the approach of Positive Matrix Factorization (PMF), a weighted least squares fit of a data matrix in which the weights are determined depending on the error estimates of each individual data value. This approach relies on more physically significant assumptions than methods like Principal Components Analysis which is frequently used in the analysis of soil datasets. In this paper we apply PMF to characterise the pollutant source in a set of geographically referenced soil samples taken within a 200 m radius of a site characterised by a high concentration of heavy metals. Each sample has been analysed for major and minor elements (using wavelength-dispersive X-ray fluorescence spectrometry), carbon, hydrogen and nitrogen (using a CHN elemental analyzer) and mercury (using cold-vapour atomic absorption spectrometry). Analysis of the soils using PMF resulted in a successful partitioning of variances into sources related to background soil geochemistry, organic influences and those associated with the contamination. Combining these results with a geostatistical approach successfully demarcated the main source of the combined organic and heavy metal contamination.     

Thermal behaviour of chromium electroplating sludge

Galvanic sludge is classified as a hazardous waste and incineration is one of the techniques used for its treatment. The aim of this work is to study the thermal behavior of a galvanic sludge which contains only chromium as a restriction metal. Simultaneous DTA/TG coupled with mass spectrometer tests were performed to characterize the thermal behavior of the sludge. Besides thermal analysis, sludge samples were heated in a specially designed furnace and these samples were submitted to X-ray diffraction. Vapor from the heated sludge was condensed and the particles were analyzed by EDS microprobe coupled in a scanning electron microscope. The slag formed after the calcination of the galvanic sludge was mainly composed of a mixture of calcium phosphate and fluoride. and minor concentrations of metals. A total weight loss of 34% was observed. The greatest part of this weight loss corresponds to CO2, H2O and SO2. H2O is liberated in the temperature range of 500-1,250 degrees C. CO2 in the range of 500-750 degrees C and SO2 near 1,000 degrees C. Chromium evaporation was not observed in relevant quantities, about 99.6% of the Cr remained incorporated in the slag.     

Predicting richness effects on ecosystem function in natural communities: insights from high-elevation streams

. Despite the increased complexity of experimental and theoretical studies on the biodiversity-ecosystem functioning (B-EF) relationship, a major challenge is to demonstrate whether the observed importance of biodiversity in controlled experimental systems also persists in nature. Due to their structural simplicity and their low levels of human impacts, extreme species-poor ecosystems may provide new insights into B-EF relationships in natural systems. We address this issue using shredder invertebrate communities and organic matter decomposition rates in 24 high-altitude (3200-3900 m) Neotropical streams as a study model. We first assessed the effects of stream characteristics and shredder diversity and abundance on organic matter decomposition rates in coarse- and fine-mesh bags. We found the interaction term shredder richness x shredder abundance had the most significant impact on decomposition rates in the field, although water discharge may also play a role locally. We also examined the relative contribution of the three most abundant shredders on decomposition rates by manipulating shredder richness and community composition in a field experiment. Transgressive overyielding was detected among the three shredder species, indicating complementary resource use and/or facilitation. By integrating survey and experimental data in surface response analyses we found that observed B-EF patterns fit those predicted by a linear model that described litter decomposition rates as a function of increasing shredder richness and the relative abundance of the most efficient shredders. Finally, the validity of our approach was tested in a broader context by using two independent but comparable data sets from 49 French and Swedish streams showing more complex shredder community structure. Results revealed that richness and identity effects on decomposition rates were lost with increasing shredder community complexity. Our approach of combining experimental and empirical data with modeling in species-poor ecosystems may serve as an impetus for new B-EF studies. If theory can explain B-EF in low-diversity ecosystems, it may also have credibility in more complex ones.     

Using foraging honeybees to sample an area for trace metals

The metal contents of pollen loads gathered by honeybees have been determined in areas with known concentrations of soil-borne heavy metals. The manganese, zinc, copper, and lead contents of the pollen loads reflected those of the environment, indicating that honeybee colonies might be used to sample areas.     

Characterization of radioactive particles from the Palomares accident

As a consequence of the nuclear accident that took place in Palomares (Almería, Spain) more than 40 years ago, actinides contamination is present in the area nowadays. Previous investigations performed with soil samples collected in different locations of Palomares indicate that the contamination in the area is highly inhomogeneous, suggesting the existence of radioactive particles, thus hindering the evaluation of the radiological situation. This work presents the methodology used for the location of the radioactive particles in the field and their isolation in the laboratory for further speciation and characterization studies. Colour pictures, electron microscopy images and EDX analyses show that most of the studied particles present a granular appearance with a variable grain size and a high fragmentation tendency, being plutonium and uranium the most abundant nuclear elements. Radiochemical determinations and activity isotopic ratios prove that the nuclear material is aged weapon grade plutonium arising from the Palomares accident.     

Food quality and season affect gene expression of the mucosal lectin MeML and particle sorting in the blue mussel Mytilus edulis

The blue mussel, Mytilus edulis, is able to use biochemical cues to sort food particles. Recently, a mucosal lectin (MeML) identified in pallial organs of M. edulis was suggested to play a role in the capture and sorting of food particles. The current study presents data obtained in 2010 showing that sorting efficiencies and MeML gene expression in M. edulis increased when mussels were either fed poor quality food or starved. In addition, results suggest that particle capture and degree of selection increased during the spawning period, although the quality of food delivered to mussels before the experiments seemed to have a stronger impact on particle-sorting efficiency. Overall, the impact of both endogenous (physiological status) and exogenous (food quality) factors were shown to affect the expression of MeML in mussel feeding organs, and the food sorting abilities.     

Chemical signals of epiphytic lichens in southwestern North America; natural versus man-made sources for airborne particulates

Ambient airborne particulate matter (PM) in southwestern North America consists of naturally derived desert dust, plus anthropogenic inputs from several sources. Epiphytic lichens (Usnea sp.) in this region are a useful biomonitor for the airborne PM because they derive nutrients and moisture largely from incorporated atmospheric aerosols, and not by absorption from the host tree limb from which they are suspended. Using a broad-based sampling strategy from southern Chihuahua, Mexico, to northern New Mexico, USA, we show that select elemental abundance ratios and lead isotopes from epiphytic lichens are useful for distinguishing between sources of airborne PM, and for gauging anthropogenic inputs into desert ecosystems. Abundance patterns of the trace elements La, Nd, and Sm in the lichens suggest origination from continental crust, but rare earth elements display a pronounced enrichment relative to the major element Fe by a factor of about 5. This enrichment appears related to geologic weathering, aeolian transport, and grain-size biases toward trace-element-rich mineral grains in the arid setting. Using the metal Pb as an indicator of human inputs, epiphytic lichens typically show Pb enrichments by a factor of about 25–60 over typical upper crustal values. Regional-scale differences in Pb isotope ratios of these lichens relate to different pollutant sources in southwestern North America.     

Metal separation from mixed types of batteries using selective precipitation and liquid-liquid extraction techniques

The purpose of this paper is to study metal separation from a sample composed of a mixture of the main types of spent household batteries, using a hydrometallurgical route, comparing selective precipitation and liquid-liquid extraction separation techniques. The preparation of the solution consisted of: grinding the waste of mixed batteries, reduction and volatile metals elimination using electric furnace and acid leaching. From this solution two different routes were studied: selective precipitation with sodium hydroxide and liquid-liquid extraction using Cyanex 272 [bis(2,4,4-trimethylpentyl) phosphoric acid] as extracting agent. The best results were obtained from liquid-liquid extraction in which Zn had a 99% extraction rate at pH 2.5. More than 95% Fe was extracted at pH 7.0, the same pH at which more than 90% Ce was extracted. About 88% Mn, Cr and Co was extracted at this pH. At pH 3.0, more than 85% Ni was extracted, and at pH 3.5 more than 80% of Cd and La was extracted.