Eutrophication alters social preferences in three-spined sticklebacks ( Gasterosteus aculeatus )

Algae blooms, which can be caused by eutrophication, drastically influence the ecology and behaviour of aquatic organisms. Such impact is often demonstrated in the context of mate choice and predator-prey interactions. In contrast, the influence of increased turbidity on social behaviour is less well understood, although it may have strong influence, at both the level of the individual and the population. We aimed to address this gap in our knowledge by using the well-described preference of three-spined sticklebacks (Gasterosteus aculeatus) to shoal with the larger of two shoals as model behaviour. In our experiments focal fish had the choice between two shoals of different sizes, either in clear or in turbid water containing green algae. Fish in clear water spent significantly more time near the larger shoal, while fish in algae water showed no significant preferences. Furthermore, fish tested in clear water changed more often between the shoals than fish tested in algae water. These results indicate that eutrophication-induced algae blooms have the potential to alter social decisions of sticklebacks. Such changes of social decisions do not only influence the behaviour of individuals, furthermore it might influence entire populations. This might eventually lead to changes of the structure of the social syste

The h-index and self-citations

Engqvist L, Frommen JG. The h-index and self-citations. Trends in Ecology & Evolution. 2008;23(5):250-252

Simplified Flow and Reactive Transport Modeling to Support Decision-Making about Water Management Strategies

In the Indian metropolis of Delhi, the Yamuna River is highly influenced by sewage water, which has led to elevated ammonium (NH4+) concentrations up to 20 mg/L in the river water during 2012–2013. Large drinking water production wells located in the alluvial aquifer draw high shares of bank filtrate. Due to the infiltrating river water, the raw water NH4+ concentrations in some wells exceed the threshold value of 0.5 mg/L ammonia-N of the Indian drinking water specifications, making the water unfit for human consumption without prior treatment. However, to meet the city’s growing water demand, it might be advantageous to consider the long-term use of the well field. This requires the development of an adapted post-treatment unit in concert with an adjusted well field management. To better understand the groundwater dynamics and contamination and decontamination times at the well field, a theoretical modeling study has been conducted. The results of 2D numerical modeling reveal that the groundwater flux beneath the river is negligible because of the aquifer and river geometry, indicating that infiltrating river water is not diluted by the ambient groundwater. Increasing the water abstraction in the wells closest to the river would result in a larger share of bank filtrate and a decreasing groundwater table decline. Simplified 1D reactive transport models set up for a distance of 500 m (transect from the riverbank to the first production well) showed that the NH4+ contamination will prevail for the coming decades. Different lithological units of the aquifer (sand and kankar—a sediment containing calcareous nodules) have a strong influence on the respective contamination and decontamination periods, as the retardation of NH4+ is higher in the kankar than in the sand layer. Although this simplified approach does not allow for a quantification of processes, it can support decision-making about a possible future use of the well field and point to associated research needs

Computer animations of color markings reveal the function of visual threat signals in Neolamprologus pulcher

© The Author (2016). Visual signals, including changes in coloration and color patterns, are frequently used by animals to convey information. During contests, body coloration and its changes can be used to assess an opponent's state or motivation. Communication of aggressive propensity is particularly important in group-living animals with a stable dominance hierarchy, as the outcome of aggressive interactions determines the social rank of group members. Neolamprologus pulcher is a cooperatively breeding cichlid showing frequent within-group aggression. Both sexes exhibit two vertical black stripes on the operculum that vary naturally in shape and darkness. During frontal threat displays these patterns are actively exposed to the opponent, suggesting a signaling function. To investigate the role of operculum stripes during contests we manipulated their darkness in computer animated pictures of the fish. We recorded the responses in behavior and stripe darkness of test subjects to which these animated pictures were presented. Individuals with initially darker stripes were more aggressive against the animations and showed more operculum threat displays. Operculum stripes of test subjects became darker after exposure to an animation exhibiting a pale operculum than after exposure to a dark operculum animation, highlighting the role of the darkness of this color pattern in opponent assessment. We conclude that (i) the black stripes on the operculum of N. pulcher are a reliable signal of aggression and dominance, (ii) these markings play an important role in opponent assessment, and (iii) 2D computer animations are well suited to elicit biologically meaningful short-term aggressive responses in this widely used model system of social evolution

Anthropogenic and geogenic influences on peri-urban aquifers in semi-arid regions: insights from a case study in northeast Jaipur, Rajasthan, India

Rapid urbanization has exerted considerable pressure on groundwater resources in Jaipur, India. Peri-urban areas are particularly affected as the public supply infrastructure often does not reach this fast-growing fringe, which often lacks a planning strategy, leading to an informal water supply based on groundwater. At the same time, the hills and historic reservoirs located in these areas are important for groundwater recharge and, therefore, critical for sustainable groundwater-resource management. To understand the local hydrogeology and the role of anthropogenic influences, a 2-year field study was carried out in northeastern Jaipur. The aim was to develop a conceptual model on which a management concept can be built. The study comprised hydrochemical and stable isotope analyses of water samples, depth-to-water measurements, a leveling survey and geophysical investigations. The study revealed that the groundwater from both the Proterozoic hard rock and the overlying Quaternary alluvial aquifer generally does not meet the Indian drinking water thresholds for nitrate concentration and/or total dissolved solids (TDS). While anthropogenic activities are the main source of quantity problems (declining groundwater levels through overabstraction), the biggest quality problems (nitrate up to 550 mg/L and TDS >500 mg/L) are most likely of geogenic origin and only enhanced by anthropogenic impacts. Quantity and quality aspects improve significantly in areas influenced by recharge from the historic reservoirs, leading to the conclusion that artificial recharge structures may be the way forward to improving community water supply and that groundwater protection should be given priority in these areas

Individual behavioural responses of an intermediate host to a manipulative acanthocephalan parasite and the effects of intra-specific parasite competition

© 2018 Timo Thünken. Background: Parasites with complex life cycles depend on the ingestion of their intermediate host by the final host. To complete their life cycle successfully, parasites frequently manipulate the behaviour and appearance of the intermediate host. Within host–parasite systems, there is considerable variation in the intermediate host’s behavioural response to infection. Aim: Identify sources of parasite-induced variation in intermediate hosts’ traits by focusing on intra- and inter-individual variation in behavioural responses to parasitic manipulation, taking infection intensity – and thus parasitic competition – into account. Organism: The acanthocephalan parasite Polymorphus minutus, which alters the phototactic behaviour and activity of its intermediate host, Gammarus pulex, thereby increasing the probability of being eaten by the final host. Methods: We repeatedly examined the behaviour of individual G. pulex varying in intensity of infection with P. minutus from uninfected to multiple-infected. We analysed phototactic responses and activity. Results and conclusions: Individual gammarids differed in phototactic behaviour and in activity patterns, with repeatability ranging from 20% to 50%. Infected gammarids showed greater between-individual variation in phototaxis but not activity than uninfected gammarids. All uninfected gammarids were photophobic, whereas the phototactic behaviour of infected gammarids ranged from photophobia to photophilia. On average, multiple-infected gammarids were similarly photophobic as uninfected ones. Single-infected gammarids were less photophobic than uninfected and multiple-infected conspecifics. This suggests that intra-specific parasitic competition affects the manipulative abilities of parasites. Both groups of infected gammarids were on average less active than uninfected ones, and this effect was mainly driven by some infected individuals. In conclusion, behavioural variation of gammarids was caused both by individual differences in responses to manipulation/infection, and by the reduced manipulative capacities of parasites facing intra-specific competition

Synthesis and Properties of Magnesium Tetrahydroborate, Mg(BH4)2

Mg(BH4)2 is one of the few complex hydrides which have the potential to meet the requirements for hydrogen storage materials, because it contains 14.9 mass% H and has suitable thermodynamic properties. It has not been investigated for hydrogen storage applications yet. In this study, several ways to synthesize solvated and desolvated magnesium tetrahydroborate by wet chemical and mechanochemical methods were tested and compared. A direct synthesis by a reaction of MgH2 with aminoboranes yields magnesium tetrahydroborate quantitatively and in pure form. The method is also applicable to the synthesis of other tetrahydroborates. The products were characterized by elemental analysis, in situ X-ray diffraction (XRD), infrared spectroscopy (FTIR), and thermal analysis methods, such as thermogravimetric analysis (TGA-DSC) and high-pressure calorimetry under a hydrogen atmosphere (HP-DSC)

Rare Earth Borohydrides—Crystal Structures and Thermal Properties

Rare earth (RE) borohydrides have received considerable attention during the past ten years as possible hydrogen storage materials due to their relatively high gravimetric hydrogen density. This review illustrates the rich chemistry, structural diversity and thermal properties of borohydrides containing RE elements. In addition, it highlights the decomposition and rehydrogenation properties of composites containing RE-borohydrides, light-weight metal borohydrides such as LiBH4 and additives such as LiH