Comparison of the interactions in the rare gas hydride and Group 2 metal hydride anions

We study both the rare gas hydride anions, RG–H− (RG = He–Rn) and Group 2 (Group IIa) metal hydride anions, MIIaH− (MIIa = Be–Ra), calculating potential energy curves at the CCSD(T) level with augmented quadruple and quintuple basis sets, and extrapolating the results to the basis set limit. We report spectroscopic parameters obtained from these curves; additionally, we study the Be–He complex. While the RG–H− and Be–He species are weakly bound, we show that, as with the previously studied BeH− and MgH− species, the other MIIaH− species are strongly bound, despite the interactions nominally also being between two closed shell species: M(ns2) and −(1s2). We gain insight into the interactions using contour plots of the electron density changes and population analyses. For both series, the calculated dissociation energy is significantly less than the ion/induced-dipole attraction term, confirming that electron repulsion is important in these species; this effect is more dramatic for the MIIaH− species than for RG–H−. Our analyses lead us to conclude that the stronger interaction in the case of the MIIaH− species arises from sp and spd hybridization, which allows electron density on the MIIa atom to move away from the incoming H−

Travel and the climate crisis: exploring COVID-19 impacts and the power of stories to encourage change

Purpose – The natural environment is facing unprecedented times owing to rising temperatures from carbon emissions, which travel-related industries contribute significantly towards. The recent global COVID-19 outbreak should be a wake-up call for the industry, as vulnerabilities have been laid bare. The current challenges should be used as a motivation to change the meaning of travel to support the global warming crisis. This paper aims emphasis that, by means of new stories, new values, beliefs and ultimately travel behaviours can be rewritten. Design/methodology/approach/ – This study embraces a pragmatic approach to research. To ensure plausibility, credibility and relevance, the research carried out multi-disciplinary analysis of secondary data, information, knowledge and draws on current developing trends. Findings – The travel community needs to take responsibility and start reducing its carbon footprint and as carbon neutrality is increasingly a global priority. Accordingly, this research considers potential future travel-related behaviours that could support more carbon-neutral travel. Significantly, it notes how the COVID-19 outbreak has offered insights into potential positive changes. To benefit from these changes, new stories for industry providers are necessary to encourage more carbon-neutral travel practices. Originality/value – This paper offers timely and original discussions on the future of travel as a result of COVID-19 impacts. It draws on the power of storytelling as a means of achieving behavioural change in the travel community to support the challenge of climate change

The future past of travel: adventure tourism supporting humans living on the edge of existence

Purpose – By drawing on current reports, this paper positions that Homo sapiens could in the near future be faced with an increasingly uninhabitable planet. It emphasises the importance of adventure tourism and its associated activities as a means of supporting individuals to develop more outdoor survival skills. Design/methodology/approach – This study applies a scenario narrative approach in exploring and presenting potential future ideas. The significance of narratives lies at the essential examination of current trends and drivers that could be shaping future scenarios. This paper, through the exploration of past and current trends supports the researcher in presenting future views. The scenario narratives in this research are established via desk-based research and inspection of academic journals, industry reports, ideas and knowledge. Findings – If society is pushed to the brink of extinction due to a catastrophic event(s), people will require survival skills, similar to those shared by our hunter-gather nomad ancestor. Thus, this paper highlights the value and importance of the industry in encouraging soft and hard outdoor adventure in the coming years. It recognises how different adventure travel activities can support people in rekindling with our more basic instincts and ultimately, surviving in different natural environments. Originality/value – This paper offers original theoretical knowledge within the adventure tourism literature. Offering original consideration to the value of exploring the past as a method of understanding the future, the paper presents an original spectrum of soft and hard skills-based adventure tourism activities

Salmon lice nauplii and copepodids display different vertical migration patterns in response to light

Light is a fundamental environmental cue which influences the migration of many marine organisms. For the salmon louse Lepeophtheirus salmonis, light is believed to drive the diel vertical migration behaviour of their planktonic larvae. Salmon lice are of critical importance to the salmonid industry due to the damage they cause to wild and farmed hosts. Salmon lice larvae have an eyespot and are positively phototactic, yet how light intensity alters their vertical distribution remains unclear. Here, we tested how light intensity (0, 0.5, 10 and 80 µmol m-2 s-1), dispersal duration (1, 4 and 12 h) and release point (surface or bottom) influenced the vertical migration of salmon lice nauplii and copepodids under controlled conditions in experimental columns. Overall, higher light intensity increased the proportion of nauplii that aggregated at the surface. Copepodid behaviour differed from that of nauplii, as they swam upwards in both light and fully dark conditions, and surface aggregations increased with dispersal duration. Results from the experiments did not support the existing view that light strongly influences the vertical position of copepodids in the water column. Combined with previous work, our results reveal that salmon lice larval stages display different vertical responses to light, temperature and salinity, which may be explained by the different strategies of nauplii (maximise survival and dispersal) and copepodids (maximise host-finding success). Our results have implications for salmon lice dispersal models, where responses of copepodids and nauplii to light are currently parametrised by the same equations. Implementing stage-specific behaviours towards light may improve the outputs of dispersal models.publishedVersio

Differential effects of internal tagging depending on depth treatment in Atlantic salmon: a cautionary tale for aquatic animal tag use.

Electronic tags are widespread tools for studying aquatic animal behavior; however, tags risk behavioral manipulation and negative welfare outcomes. During an experiment to test behavioral differences of Atlantic salmon Salmo salar in different aquaculture cage types, including ones expected to elicit deeper swimming behavior, we found negative tagging effects depending on whether cages were depth-modified. In the experiment, data storage tags implanted in Atlantic salmon tracked their depth behavior and survival in unmodified sea-cages and depth-modified sea-cages that forced fish below or into a narrow seawater- or freshwater-filled snorkel tube from a 4 m net roof to the surface. All tagged individuals survived in unmodified cages; however, survival was reduced to 62% in depth-modified cages. Survivors in depth-modified cages spent considerably less time above 4 m than those in unmodified cages, and dying individuals in depth-modified cages tended to position in progressively shallower water. The maximum depth that fish in our study could attain neutral buoyancy was estimated at 22 m in seawater. We calculated that the added tag weight in water reduced this to 8 m, and subtracting the tag volume from the peritoneal cavity where the swim bladder reinflates reduced this further to 4 m. We conclude that the internal tag weight and volume affected buoyancy regulation as well as the survival and behavior of tagged fish. Future tagging studies on aquatic animals should carefully consider the buoyancy-related consequences of internal tags with excess weight in water, and the inclusion of data from dying tagged animals when estimating normal depth behaviors.publishedVersio

The gill parasite Paramoeba perurans compromises aerobic scope, swimming capacity and ion balance in Atlantic salmon.

The parasitic amoeba Paramoeba perurans is an aetiological agent of amoebic gill disease (AGD), a serious problem in seawater salmonid aquaculture globally. Other finfish species are also infected and infection events may be associated with periods of unusual high temperatures. Currently little is known about the impact of AGD on wild fish, but in a time with global warming and increasing aquaculture production this potential threat could be on the rise. A better understanding of the pathophysiology of infected fish is therefore warranted. In this study, groups of Atlantic salmon with and without AGD were tested in a large swim tunnel respirometer in seawater at 13°C to assess oxygen uptake, swimming capacity and blood parameters. Standard metabolic rates were similar between groups, but the maximum rate of oxygen uptake was drastically reduced in infected fish, which resulted in a smaller aerobic scope (AS) of 203 mg O2 kg−1 h−1 compared to 406 mg O2 kg−1 h−1 in healthy fish. The critical swimming speed was 2.5 body lengths s−1 in infected fish and 3.0 body lengths s−1 in healthy ones. Furthermore, AGD fish had lower haematocrit and [haemoglobin], but similar condition factor compared to healthy fish. Prior to swim trials infected fish had higher plasma osmolality, elevated plasma [Na+], [Cl-] and [cortisol], indicating reduced capacity to maintain ionic homoeostasis as well as chronic stress during routine conditions. These results demonstrate that AGD compromises gill function both in terms of gas exchange and ion regulation, and consequently the capacity for aerobic activity is reduced. Reduced AS due to the P. perurans infections is likely to interfere with appetite, growth and overall survival, even more so in the context of a warmer and more hypoxic future.publishedVersio

Free-living Neoparamoeba perurans depth distribution is mostly uniform in salmon cages, but reshaped by stratification and potentially extreme fish crowding

Understanding the spatio-temporal positioning of hosts and their parasites in free-living states is useful in devising methods to diminish parasite encounters in animal production systems. We explored the potential for depth-based control methods of the amoebic gill disease (AGD) agent, Neoparamoeba perurans, in salmon mariculture systems by conducting: (1) depth-stratified N. perurans water sampling surveys in 2 years, and (2) a mensurative experiment comparing depth distributions of N. perurans and salmon hosts in commercial salmon sea-cages. From water sampling mostly at marine salinities, N. perurans abundance (quantitative PCR-derived cells l-1) varied among years, but overall, neither depth, time since freshwater bathing, temperature and salinity were predictors of N. perurans abundance. However, at 1 survey time, depth patterns in N. perurans abundance appeared during strong vertical salinity gradients following rainfall (at 1 site, salinity ranged between 14 and 35 g l-1), with greater numbers of cells below a less saline surface layer. This suggested that salinity mediates N. perurans depth distribution during intermittent halocline development. Fish depth distribution monitoring revealed intense fish crowding, with local swimming densities up to 5 times stocking densities, typically at the surface at night. Simultaneously collected daytime water samples during low levels of fish crowding, with stock scattered amongst upper and lower cage sections, revealed no relationship between N. perurans and fish depth distributions. If intense fish crowding in narrow depth bands leads to high concentrations of N. perurans in cage environments and increased AGD risk, behavioural manipulations that vertically spread fish could be a successful AGD mitigation strategy.publishedVersio

Becoming immortal: future wellness and medical tourism markets

Purpose – Is humanity heading to immortal living? If so, what areas of society are playing an active role in achieving this? In order to understand this, the study explores the relationship between immortality and the wellness and medical tourism industry to seek potential relationships between them and ultimately, asks difficult questions about the growth of these tourism sectors and the potential need for greater regulation of them. Design/methodology/approach – Taking a pragmatic philosophical approach and through the examination of refined information from secondary sources and published material and reports, the study presents original theoretical knowledge and a model exploring tourism and human immortality. Findings – This paper argues that continued growth in the wellness and medical markets today could lead to a world where transhumanists and cyborgs are present in our world, even taking over from Homo sapiens. The study presents a model highlighting the potential role of wellness and medical tourism markets, illustrating the potential for future consumer services that could further fuel the search for immortality. Thus, how such markets and consumer desires are (in)directly supporting humanities desire for (non-human) immortal existence. Originality/value – Today, individuals are driven by wellness practices and medical and cosmetic desires and are willing to travel the globe in search of companies who are either capable of carrying out the desired procedures or seeking prices more affordable to them. This research offers novel insights into these complex relationships and maps the affiliation between wellness and medical practices and the concept of immortality