Alien macroinvertebrates in Flanders (Belgium)

Biological invasions of aquatic macroinvertebrates are gaining interest because of their potential for significant ecological and socio-economic impacts (positive and negative). In the present study, an inventory was made of the alien macroinvertebrates occurring in Flanders (northern Belgium) based on extensive existing collections of biological samples and supplemented with our additional sampling programs. Fresh and brackish waters as well as the Belgian coastal harbours, situated at the interface of the marine environment, were investigated. Over 2,500 samples containing alien macroinvertebrates were identified to species level, which allowed us to accurately map their distribution in Flanders. Alien macroinvertebrates are widespread and abundant in many watercourses in Flanders. Four new macroinvertebrate species for Flanders were discovered: Procambarus clarkii (Girard, 1852), Echinogammarus trichiatus (Martynov, 1932), Synurella ambulans (F. Müller, 1846) and Laonome calida Capa, 2007. Fifty-two alien macroinvertebrates were encountered in fresh and slightly brackish surface waters, and 21 alien species were reported for the Belgian part of the North Sea and its adjacent estuaries. Most alien macroinvertebrates collected were crustaceans and molluscs. Alien species found in fresh and brackish water mainly originate from the Ponto-Caspian area and North America; fewer species originated from Asia and South- and East-Europe. The major pathways were probably shipping and dispersal through canals. Based on observations in neighbouring countries, several additional species are expected to arrive in the near future. Follow-up work is needed to assess the ecological and economic impacts of existing alien macroinvertebrates, and a monitoring program is needed to detect new incoming species

Emigration of European silver eel (Anguilla anguilla L.) from a polder system into the Schelde estuary

Connectivity between freshwater habitats and marine areas is heavily obstructed by migration barriers, leading to a high pressure on diadromous eel populations. Migration barriers attribute to the 98% decline of the European eel (Anguilla anguilla L.) population. A better understanding of eel behaviour regarding these barriers is needed for water managers to take proper mitigation actions. We tracked 50 eels by means of acoustic telemetry between July 2012 and January 2015 and analysed their migration behaviour in a Belgian polder area. On their way to the Schelde Estuary, eels face several migration barriers such as a pumping station, a weir and tidal barriers. The telemetry study did reveal significant delays and searching behaviour near those barriers. Depending on nothing but their accumulated fat, delays can have a serious impact on the fitness of the eel by wasting precious energy resources needed for a successful trans-Atlantic migration. In addition, delays and searching behaviour can also increase predation risk. The obtained knowledge can contribute to efficient management such as improved fish passage and guidance solutions

Innovative Visualizations Shed Light on Avian Nocturnal Migration

We acknowledge the support provided by COST–European Cooperation in Science and Technology through the Action ES1305 ‘European Network for the Radar Surveillance of Animal Movement’ (ENRAM) in facilitating this collaboration. We thank ENRAM members and researchers attending the EOU round table discussion ‘Radar aeroecology: unravelling population scale patterns of avian movement’ for feedback on the visualizations. We thank Arie Dekker for his feedback as jury member of the bird migration visualization challenge & hackathon hosted at the University of Amsterdam, 25–27 March 2015. We thank Willem Bouten and Kevin Winner for discussion of methodological design. We thank Kevin Webb and Jed Irvine for assistance with downloading, managing, and reviewing US radar data. We thank the Royal Meteorological Institute of Belgium for providing weather radar data.Globally, billions of flying animals undergo seasonal migrations, many of which occur at night. The temporal and spatial scales at which migrations occur and our inability to directly observe these nocturnal movements makes monitoring and characterizing this critical period in migratory animals’ life cycles difficult. Remote sensing, therefore, has played an important role in our understanding of large-scale nocturnal bird migrations. Weather surveillance radar networks in Europe and North America have great potential for long-term low-cost monitoring of bird migration at scales that have previously been impossible to achieve. Such long-term monitoring, however, poses a number of challenges for the ornithological and ecological communities: how does one take advantage of this vast data resource, integrate information across multiple sensors and large spatial and temporal scales, and visually represent the data for interpretation and dissemination, considering the dynamic nature of migration? We assembled an interdisciplinary team of ecologists, meteorologists, computer scientists, and graphic designers to develop two different flow visualizations, which are interactive and open source, in order to create novel representations of broad-front nocturnal bird migration to address a primary impediment to long-term, large-scale nocturnal migration monitoring. We have applied these visualization techniques to mass bird migration events recorded by two different weather surveillance radar networks covering regions in Europe and North America. These applications show the flexibility and portability of such an approach. The visualizations provide an intuitive representation of the scale and dynamics of these complex systems, are easily accessible for a broad interest group, and are biologically insightful. Additionally, they facilitate fundamental ecological research, conservation, mitigation of human–wildlife conflicts, improvement of meteorological products, and public outreach, education, and engagement.Yeshttp://www.plosone.org/static/editorial#pee

Microbial fuel cells for the treatment of waste streams with energy recovery

Aerobic wastewater treatment is energy and resource intensive. As a consequence, the accessibility of clean water is closely related to the availability of energy. Interestingly, wastewater itself is a source of chemical energy, indeed 1 kg of carbohydrates corresponds to roughly 4 kWh of energy. The question is how to convert the chemical energy into a practical energy source which can be used on the spot. Microbial fuel cells (MFCs) enable to recover the chemical energy during the treatment of various organic (waste)streams as electricity. A typical MFC consists of an anode and a cathode compartment which are separated by a proton exchange membrane. In the anode compartment a substrate is microbially oxidized. During this microbial oxidation, not only protons and oxidized products are formed but remarkably electrons are transferred from the bacteria towards a solid electrode. The electrons flow through an electrical circuit towards the cathode where a final electron acceptor is reduced. The flow of electrons together with the positive potential difference between the anode and cathode, give rise to the generation of electrical power. The use of microorganisms to catalyze the electrochemical oxidation of organics is highly attractive as it allows to take advantage of the versatility and resilience which bacteria exert. However, to date no firm microbial characterization has been performed and there is a need for practical operational parameters to stimulate the growth and activity of bacteria. In addition, powerful and sustainable MFC reactors are needed for the direct conversion of wastewater into electricity at a practical energy level. The presence of an electrochemical active microbial community is essential to generate high power outputs using MFCs. Moreover, during this research, the evolution of the electrochemical and microbial features of MFCs have been related. During a continuous operation of about 3 months, a notable shift of both the microbial community and the maximum power output was noted. Whereas 6 MFCs had initially 6 different microbial communities, they all evolved to a specific consortium which was dominated by a Gram positive Brevibacillus species. The enrichment accompanied a decrease of the internal losses of the reactors, a shift in the polarization curves and an overall increase of the power outputs. However as this selection occurred autonomous, the question was raised how this selection could be steered, resulting in the faster growth of a highly active microbial community. Therefore, the operational parameters determining the activity of the microbial catalyst have been investigated. The anode potential is associated with the energy metabolism of the electrochemical active microorganisms. It is hypothesized that the higher the anode potential is, the more metabolic energy there is available for the bacteria, but the lower the power output for the consumer will be. During this research three MFCs were poised at an anode potential of respectively 0 (R0), -200 (R-200) and -400 (R-400) mV versus a Ag/AgCl reference electrode. However, R-200 had overall the highest performance. Indeed, during the 31 day test period, R 200 produced 15% more charge compared to R0 and R-400. In addition, R-200 had the highest maximal power density (up to 199 W.m-3 total anode compartment (TAC) during polarization). Conversely, the reactor poised at -400 mV had overall the lowest current and power generation. Moreover, during polarization, a sharp levelling of the current at an anode potential of -300 mV versus Ag/AgCl was noted. This was associated with a lower availability of energy to invest in electron conducting mechanisms. The maximum respiration rate of the bacteria during batch tests was also considerably lower for R-400. The specific biomass activity however, was the highest for R-400 (6.93 g COD.g-1 biomass-VSS.d-1 on day 14). However, this value lowered during the course of the experiment due to an increase of the biomass concentration to an average level of 578 +- 106 mg biomass-VSS L-1 graphite granules for the three reactors. This research indicated that an optimal anode potential of 200 mV versus Ag/AgCl exists, regulating the activity of bacteria to sustain an enhanced current and power generation. In spite of the importance of the anode potential, it might be a difficult to control parameter in future industrial MFCs. Closely related to the anode potential, is the applied external resistance. The latter controls the ratio of the MFC cell voltage and the current generation and as a consequence also determines the maximum power output. During this research, the influence of the external resistance and the loading rate on the electricity generation was investigated. During the experiments it was found that a doubling of the loading rate to 3.3 g COD.L-1 TAC.d-1 resulted only in an increased current generation when the external resistance was low (10.5 – 25 Ω) or during polarization. It was hypothesized that the amount of energy which was available for growth and maintenance of the bacteria, as determined by the external resistance, was probably too low to sustain a higher metabolic activity. Therefore, an increase of the loading rate needs to be accompanied by a decrease of the external resistance in order to increase the continuous current generation. Conversely, a lowering of the external resistance resulted in a concise and steady increase of both the kinetic capacities of the biocatalyst and the continuous current generation from 77 (50 ohm) up to 253 (10.5 ohm) A.m-3 TAC. Interestingly, lowering the external resistance will not necessarily result in a lower power output as our result showed that both the continuous current generation, power generation and the coulombic efficiency increased at lower external resistances. In general, when the external resistance approaches the internal resistance of the MFC, the increased current will be accompanied with a higher power output. Next, it is important to attune the external resistance and the volumetric loading rate. In a second line, improvements of the MFC technology were proposed to boost the power output to practical level and to improve the sustainability of MFCs. A new MFC design was developed consisting of 1.5 cm thin anode and cathode compartments which were filled with a three dimensional electrode structure. As graphite and carbon electrodes have many properties which render them highly suited for the application in MFCs, different structures (felt, granules and wool) of these materials were tested. When operated at an external resistance of 10.5 ohm and at a loading rate of 3.3 g COD L-1.d-1, the use of a three-dimensional graphite felt electrode yielded the highest power output amounting up to 386 W.m-3 TAC which was a factor 1.5 higher compared to a graphite granules electrode. The increase was probably due to a decrease of the contact losses. Conversely, the use of smaller graphite granules, resulted in a lower power and current generation. A possible issue remains the clogging of the anode compartment when wastewater containing particulates is used. Moreover, when the anode compartment thickness of an open air cathode MFC was increased from 1.5 to 7.5 cm, this resulted in a lowering of the power and current density. Therefore, a clever solution to enable a proportional increase of current while increasing the anode thickness will be needed. Due to the microbial boundaries and physical constraints, the absolute voltage and current of MFCs is limited. To increase the voltage and current to practical levels, the connection of multiple MFCs in series or parallel will be needed. However, the effect on the microbial activity of the series or parallel connection has not been investigated yet and was a subject of this research. The connection of the 6 MFC units in series and parallel enabled an increase of the voltages (2.02 V at 88 W.m-3 TAC) and the currents (255 mA at 95 W.m-3 TAC), while retaining high power outputs. The fact that the maximum power outputs were unaffected by the series or parallel connection is important for future application. However, during the connection in series, it was noted that the individual MFC voltages diverged at increasing currents, moreover some MFCs even switched polarity. As a consequence, an important drawback of the series connection was revealed: cell reversal. This phenomenon typically occurred when the current delivered by the in series connected MFC was higher than the current generation of the subunits. Ensuring an equal feed and - as we suggest - an equal catalyst (microbial and chemical) activity in the anode and cathode compartments, is crucial to prevent cell reversal. However, more research is needed to elucidate the exact reasons. The use of non-noble metal based cathodes can enhance the sustainability of MFCs. We demonstrated that an iron chelated complex could effectively be used as a catholyte or as an iron chelated open air cathode to generate current with the use of MFCs. An iron ethylenediaminetetraacetic acid (Fe-EDTA) catholyte generated a maximum current of 34.4 mA and a maximum power density of 22.9 W.m-3 total anode compartment (TAC). Compared to a MFC with a hexacyanoferrate catholyte, the maximum current was similar but the maximum power was 50% lower. However, no replenishment of the Fe-EDTA catholyte was needed. The creation of an activated carbon cloth open air cathode with Fe-EDTA- polytetrafluoroethylene (PTFE) applied to it increased the maximum power density to 40.3 W.m-³ TAC and generated a stable current of 12.9 mA (at 300 mV). It was observed that the ohmic loss of an open air cathode MFC was dependent on the type of membrane used. The development of specifc membranes for MFCs and the search for highly active cathodes are crucial for the future application of MBCs. The outcome of this research was fuelled by the quest towards the ultimate goal of MFC technology: the implementation as an energy efficient wastewater treatment. Therefore, in a third line, the use of MFCs as a technology for the treatment of wastewaters was explored. The treatment of a potato processing wastewaters and a hospital wastewater effluent with a MFC resulted in a power generation of up to 22 W.m-3 TAC. However, the power generation was dependent upon the buffer capacity of the wastewater. Moreover, the COD removal efficiency needs to be improved. Finally, a set of process configurations in which MFCs could be useful to treat wastewaters is schematized. To conclude, this research has resulted in new insights which are helpful for the future application of MFCs in the domain of wastewater treatment. This research provided a further characterization of the microbial catalysts, the important operational parameters for MFCs have been investigated and new technological advances have been proposed. The study of microorganisms in a “energetically controlled environment” is unique and allows to explore the microbial metabolism at a new level. It is expected that, next to the recovery of energy out of wastewater, many new applications for MFCs will emerge

Student teachers' professional identity formation: between being born as a teacher and becoming one

This article focuses on student teachers' professional identity formation inspired by the tension between two layman points of view namely: being born as a teacher (i.e. based on demographics and personality traits) and becoming a teacher (i.e. based on experience). Besides demographics, personality traits and experience, the teacher preparation context is considered as a crucial aspect in professional identity formation as well. The authors adopted a multiple theoretical approach to guide the empirical study. Using hierarchical regression analyses the relative influences of demographics and personality traits, context variables and teacher education variables on professional identity variables are explored

Litre-scale microbial fuel cells operated in a complete loop.

Using the anode effluent to compensate the alkalinization in a bio-cathode has recently been proposed as a way to operate a microbial fuel cell (MFC) in a continuous and pH neutral way. In this research, we successfully demonstrated that the operation of a MFC without any pH adjustments is possible by completing the liquid loop over cathode and anode. During the complete loop operation, a stable current production of 23.2 +/- 2.5 A m(-3) MFC was obtained, even in the presence of 3.2-5.2 mg O-2 L-1 in the anode. The use of current collectors and subdivided electrical circuitries for relative large 2.5-L-scale MFCs resulted in ohmic cell resistances in the order of 1.4-1.7 m Omega m(3) MFC, which were comparable to values of ten times smaller MFCs. Nevertheless, the bio-cathode activity still needs to be improved significantly with a factor 10-50 in order achieve desirable current densities of 1,000 A m(-3) MFC

Bioanode performance in bioelectrochemical systems: recent improvements and prospects

In a bioelectrochemical system (BES) operated with a bioanode, the anode performance plays an important part in the overall performance. Fundamental aspects of bioanodes have been intensively investigated, enabling us to better understand the growth, kinetics functioning and interactions of anodophilic microorganisms. Recently, various technological advances have improved the properties and operation of anodes and have increased bioanode performance by up to tenfold. To further boost the performance of bioanodes by several orders of magnitude, practical microbiological approaches deserve more investigation. This article reviews the factors affecting bioanode performance, the recent advances and the prospective strategies for improving it. Future application perspectives of bioanodes are also proposed