Development and validation of an individual based Daphnia magna population model: The influence of crowding on population dynamics

An individual-based model was developed to predict the population dynamics of Daphnia magna at laboratory conditions from individual life-history traits observed in experiments with different feeding conditions. Within the model, each daphnid passes its individual life cycle including feeding on algae, aging, growing, developing and – when maturity is reached – reproducing. The modelled life cycle is driven by the amount of ingested algae and the density of the Daphnia population. At low algae densities the population dynamics is mainly driven by food supply, when the densities of algae are high, the limiting factor is “crowding” (a density-dependent mechanism due to chemical substances released by the organisms or physical contact, but independent of food competition).     

Fate of 17β-estradiol in terrestrial model ecosystems amended with contaminated composted biosolids

Biosolids spread onto agricultural soils are potential sources of steroidal hormones that are able to adversely affect the soil ecosystem. Here we studied the fate of the [4-¹⁴C]-17-β-estradiol hormone in laboratory experiments. First, our results show that only 2.9% of the hormone was mineralized in the soil from a French vineyard. By contrast, the mineralization increased to 7.1% when the hormone was provided in composted biosolids. Second, we found that only a minor part of the estradiol-derived ¹⁴C was mobile and partly transferred to soil leachates. Indeed, the hormone was mainly stabilized in the soil as non-extractable residues. Overall, our findings show that estradiol undergoes two main processes, complete degradation and stabilisation. We therefore conclude that the environmental risk of hormones provided to the soil through composted biosolids is negligible under the conditions of our experiments.     

Remote Antarctic feeding ground important for east Australian humpback whales

Understanding the dynamics of population recovery is particularly complex when an organism has multiple, remote breeding and feeding grounds separated by one of the longest known migration routes. This study reports on the most comprehensive assessment of humpback whale (Megaptera novaeangliae) movements between remote Antarctic waters south of New Zealand and east Australia (EA), and the migratory corridors and breeding grounds of Australia and Oceania. A total of 112 individual whales were identified; 57 from microsatellites and 61 by fluke with 23 % (n = 26) matched to sites outside Antarctica. Despite large datasets from other southern regions being included in the comparison, the whales were predominantly linked to EA (n = 24). Only two matches to the Oceania catalogues directly north was surprising; therefore the primary feeding grounds of these endangered whales still remain unknown. The confirmation of the Balleny Islands as an important feeding ground for EA whales could provide an insight into reasons behind the rapid recovery of this population. Determining the feeding grounds of Oceania’s whales may explain whether prey energetics or migration length are limiting factors to their recovery and will allow an understanding of future ecosystem changes in these whales.     

Sensitivity analysis of Phast’s atmospheric dispersion model for three toxic materials (nitric oxide, ammonia, chlorine)

We present the results of a parametric sensitivity analysis of a widely used model for atmospheric dispersion of toxic gases, in order better to understand the influence of user-adjustable parameters on model outputs. We have studied 60 min continuous release scenarios for three different products (nitric oxide, ammonia and chlorine), chosen to cover a range of physical characteristics and storage conditions. For each product, we have broken down base-case scenarios into a number of sub-scenarios corresponding to different release conditions which determine physical phenomena (flow rate, release angle, release elevation and atmospheric stability class). The use of statistical tools to analyze the results of a large number of model executions allows us to rank model parameters according to their influence on the variability of a number of model outputs (distances and concentrations), on a per-scenario and per-product basis. Analysis of the results allows us to verify our understanding of the modeling of cloud dispersion.     

Worker reproductive parasitism and drift in the western honeybee Apis mellifera

When a honeybee (Apis spp.) colony loses its queen and is unable to rear a new one, some of the workers activate their ovaries and produce eggs. When a colony has a queen (i.e., it is queenright) almost all worker-laid eggs are eaten, but when hopelessly queenless, the workers become more tolerant of worker-laid eggs and rear some of them to adult drones. This increased tolerance renders a queenless colony vulnerable to worker reproductive parasitism, wherein unrelated workers enter the colony and lay eggs. Here, we show that the proportion of unrelated (non-natal) workers significantly decreases after an Apis mellifera colony becomes queenless. The remaining non-natal workers are as likely to have activated ovaries as natal workers, yet they produce more eggs than natal workers, resulting in significantly higher reproductive success for non-natal workers. In a second experiment, we provided queenless and queenright workers with a choice to remain in their own colony or to join a queenless or queenright colony nearby. The experiment was set up such that worker movement was unlikely to be due to simple orientation errors. Very few workers joined another colony, and there was no preference for workers to drift into or out of queenless or queenright colonies, in accordance with the proportion of non-natal workers declining significantly after becoming queenless in the first experiment.     

Estimating Relevance of Organic Carbon,Nitrogen, and Phosphorus Loads to a Blackwater River Estuary1

Abstract: In blackwater river estuaries, a large portion of external carbon, nitrogen, and phosphorus load are combined in complex organic molecules of varying recalcitrance. Determining their lability is essential to establishing the relationship between anthropogenic loads and eutrophication. A method is proposed in which organic C, N, and P are partitioned into labile and refractory forms, based upon first‐order decay estimated by biochemical oxygen demand relative to total organic carbon, and C:N and C:P ratios as a function of organic carbon lability. The technique was applied in developing total maximum daily loads for the lower St. Johns, a blackwater Atlantic coastal plain river estuary in Northeast Florida. Point source organic nutrients were determined to be largely labile. Urban runoff was found to have the highest relative labile organic N and P content, followed by agricultural runoff. Natural forest and silviculture runoff were high in refractory organic N and P. Upstream labile C, N, and P loads were controlled by autochthonous production, with 34‐50% of summer total labile carbon imported as algal biomass. Differentiation of labile and refractory organic forms suggests that while anthropogenic nutrient enrichment has tripled the total nitrogen load, it has resulted in a 6.7‐fold increase in total labile nitrogen load.     

A goal oriented indicator framework to support integrated assessment of new policies for agri-environmental systems

The goal oriented framework (GOF) for indicators has been developed as part of a comprehensive research project developing computerised tools for integrated assessment of the effects of new policies or technologies on agricultural systems (SEAMLESS-IF). The ambition has therefore been to create an indicator framework where the environmental, economic and social dimensions of sustainable development can be related to each other in a consistent way. Integrated assessment tools rely on such frameworks to capture and visualise trade-offs (antagonisms or synergies) among indicators between and within the three dimensions of sustainable development. The specific aims of this paper are to (i) present the GOF (ii) present how the GOF can be used to select indicators within the integrated assessment framework SEAMLESS-IF and (iii) discuss the advantages and limitations with the proposed approach. We show that the GOF has several advantages. Its major rewards are its relative simplicity and the possibility to link indicators to policy goals of each dimension of sustainability and thereby facilitate the comparison of the impacts of the new policy on the different dimensions. Another important feature of the GOF is its multi-scale perspective, which will enable the comparison of effects of a new policy between scales. Yet, as typical for all indicator frameworks, the GOF has also biases either instigated by the issues the included models cover or by the stakeholders’ selection of indicators. However, due to the way the GOF and its indicators are technically implemented in SEAMLESS-IF, it can easily be extended and include new indicators to increase and update its policy relevance.     

BRC4Env,a network of Biological Resource Centres for research in environmental and agricultural sciences

The Biological Resource Centre for the Environment BRC4Env is a network of Biological Resource Centres (BRCs) and collections whose leading objectives are to improve the visibility of genetic and biological resources maintained by its BRCs and collections and to facilitate their use by a large research community, from agriculture research to life sciences and environmental sciences. Its added value relies on sharing skills, harmonizing practices, triggering projects in comparative biology, and ultimately proposing a single-entry portal to facilitate access to documented samples, taking into account the partnership policies of research institutions as well as the legal frame which varies with the biological nature of resources. BRC4Env currently includes three BRCs: the Centre for Soil Genetic Resources of the platform GenoSol, in partnership with the European Conservatory of Soil Samples; the Egg Parasitoids Collection (EP-Coll); and the collection of ichthyological samples, Colisa. BRC4Env is also associated to several biological collections: microbial consortia (entomopathogenic bacteria, freshwater microalgae…), terrestrial arthropods, nematodes (plant parasitic, entomopathogenic, animal parasitic...), and small mammals. The BRCs and collections of BRC4Env are involved in partnership with academic scientists, as well as private companies, in the fields of medicinal mining, biocontrol, sustainable agriculture, and additional sectors. Moreover, the staff of the BRCs is involved in many training courses for students from French licence degree to Ph.D, engineers, as well as ongoing training.     

Substance use among populations displaced by conflict: a literature review

This paper reviews the literature on substance use among populations displaced by conflict. Of the 17 publications presenting primary data retained for review, all consider populations in or recovering from protracted conflict, the majority (10) in non-camp settings. Most studies (10) offer prevalence estimates, suggesting that substance use (such as of alcohol, opiates, or minor tranquilizers) is common in some displaced settings. Five describe harmful consequences of substance use among displaced populations (such as HIV transmission, tuberculosis treatment failure, gender-based violence, and economic problems). Three studies suggest risk factors for substance use problems (such as gender, trauma-related conditions, pre-displacement substance use, and socio-economic factors); two examine qualitatively the gendered nature of alcohol-related harm and its links with gender-based violence. One study examines an intervention. The evidence base is weak. Findings are used to develop a conceptual framework emphasizing the risk environment to inform further research, to encourage debate among researchers and practitioners, and to enable the development of interventions.