Environmental impacts of space technology

Gaston, K.J., Anderson, K., Shutler, J.D., Brewin, R.J.W. & Yan, X. 2023. Environmental impacts of increasing numbers of space objects. Frontiers in Ecology and Environment 21, 289-296.

For much of their existence, the environmental benefits of artificial satellites, particularly through provision of remotely sensed data, seem likely to have greatly exceeded their environmental costs. With dramatic current and projected growth in the number of Earth-observation and other satellites in low Earth orbit, this trade-off now needs to be considered more carefully. Here we highlight the range of environmental impacts of satellite technology, taking a life-cycle approach to evaluate impacts from manufacture, through launch, to burn-up during de-orbiting. These include the use of renewable and nonrenewable resources (including those associated with the transmission, long-term storage, and distribution of data), atmospheric consequences of rocket launches and satellite de-orbiting, and impacts of a changing nighttime sky on humans and other organisms. Initial estimations of the scale of some impacts are sufficient to underscore the need for more detailed investigations and to identify potential means by which impacts can be reduced and mitigated.

Entrenching biophobia

Soga, M., Gaston, K.J., Fukano, Y. & Evans, M.J. 2023. The vicious cycle of biophobia. Trends in Ecology and Evolution 38, 512-520.

People can express irrational fears and disgust responses towards certain wild organisms. This so-called ‘biophobia’ can be useful and indeed necessary in some circumstances. Biophobia can, however, also lead to excessive distress and anxiety which, in turn, can result in people avoiding interactions with nature. Here, we highlight concern that this reduction in interactions with nature might lead to progressive increases in biophobia, entrenching it more in individuals and across society. We propose the ‘vicious cycle of biophobia’, a concept that encapsulates how excessive aversion towards nature might emerge and grow in society. The vicious cycle of biophobia risks accelerating the extinction of experience, leading to long-term adverse consequences for the conservation of biodiversity.

Transcience in public attention to biological conservation

Jarić, I., Correia, R.A., Bonaiuto, M., Brook, B.W., Courchamp, F., Firth, J.A., Gaston, K.J., Heger, T., Jeschke, J.M., Ladle, R.J., Meinard, Y., Roberts, D.L., Sherren, K., Soga, M., Soriano-Redondo, A., Veríssimo, D. & Roll, U. 2022. Transience of public attention in conservation science. Frontiers in Ecology and Environment, online early.

Societal awareness of, and engagement with, environmental problems is a critical prerequisite for effective conservation programs. Research has revealed a strong general pattern whereby public attention received by cultural products diminishes over time. If transposed to conservation, this transience of societal attention is likely to be of major importance because it can limit motivation to support conservation efforts. We address the concept of attention transience applied to conservation, discuss its major drivers and mechanisms, and provide a short overview of conservation issues for which this phenomenon is expected to be particularly relevant. Attention transience leaves a brief window of opportunity for conservationists to focus public awareness and to mobilize necessary support. In this context, it is critical to maximize the conservation benefits generated during these short bursts of attention, especially through tailored conservation marketing campaigns with targeted message framing and regular efforts to refocus attention on key issues.

Population decline & timing of threats

Cox, D.T.C., Gardner, A.S. & Gaston, K.J. 2023. Diel niche variation in mammalian declines in the Anthropocene. Scientific Reports 13, 1031.

Biodiversity is being eroded worldwide. Many human pressures are most forcefully exerted or have greatest effect during a particular period of the day. Therefore when species are physically active (their diel niche) may influence their risk of population decline. We grouped 5032 terrestrial extant mammals by their dominant activity pattern (nocturnal, crepuscular, cathemeral and diurnal), and determine variation in population decline across diel niches. We find an increased risk of population decline in diurnal (52.1% of species), compared to nocturnal (40.1% of species), crepuscular (39.1% of species) and cathemeral (43.0% of species) species, associated with the larger proportion of diurnal mammals that are primates. Those species with declining populations whose activity predominantly coincides with that of humans (cathemeral, diurnal) face an increased number of anthropogenic threats than those principally active at night, with diurnal species more likely to be declining from harvesting. Across much of the land surface habitat loss is the predominant driver of population decline, however, harvesting is a greater threat to day-active species in sub-Saharan Africa and mainland tropical Asia, associated with declines in megafauna and arboreal foragers. Deepening understanding of diel variation in anthropogenic pressures and resulting population declines will help target conservation actions.

Artificial light confuses anti-predator defences

Bullough, K., Gaston, K.J. & Troscianko, J. 2023. Artificial light a night causes conflicting behavioural and morphological defence responses in a marine isopod. Proceedings of the Royal Society B 290, 20230725.

Encroachment of artificial light at night (ALAN) into natural habitats is increasingly recognized as a major source of anthropogenic disturbance. Research focussed on variation in the intensity and spectrum of ALAN emissions has established physiological, behavioural and population-level effects across plants and animals. However, little attention has been paid to the structural aspect of this light, nor how combined morphological and behavioural anti-predator adaptations are affected. We investigated how lighting structure, background reflectance and the three-dimensional properties of the environment combined to affect anti-predator defences in the marine isopod Ligia oceanica. Experimental trials monitored behavioural responses including movement and background choice, and also colour change, a widespread morphological anti-predator mechanism little considered in relation to ALAN exposure. We found that behavioural responses of isopods to ALAN were consistent with classic risk-aversion strategies, being particularly exaggerated under diffuse lighting. However, this behaviour was disconnected from optimal morphological strategies, as diffuse light caused isopods to become lighter coloured while seeking out darker backgrounds. Our work highlights the potential for the structure of natural and artificial light to play a key role in behavioural and morphological processes likely to affect anti-predator adaptations, survival, and ultimately wider ecological effects.

Benefiting biodiversity

Soga, M. & Gaston, K.J. 2023. Nature benefit hypothesis: direct experiences of nature predict self-reported pro-biodiversity behaviours. Conservation Letters 16, e12945.

Human activities are damaging the world’s ecosystems, posing a serious threat to life on Earth, including humanity. To address this situation, widespread and significant changes in human behavior are necessary. Direct experiences of nature can encourage individuals to adopt positive actions towards biodiversity (hereafter pro-biodiversity behavior), but this relationship has not been well studied. Using a large sample of Japanese adults, we demonstrate that both recent and childhood frequencies of nature experiences are associated with an increased likelihood of exhibiting pro-biodiversity behaviors. This association was found to be consistent across various forms of behaviors, including purchasing ecofriendly products, reducing pesticide use in domestic gardens, and donating to conservation organizations. However, our research also reveals a declining trend of childhood experiences of nature in Japan, resulting in an “extinction of experience.” Our results suggest that enhancing people’s personal experiences with nature could help promote desired behavioral change to halt biodiversity loss.

Functioning at night

Cox, D.T.C., Baker, D.J., Gardner, A.S. & Gaston, K.J. 2023. Global variation in unique and redundant mammal functional diversity across the daily cycle. Journal of Biogeography 50, 629-640.

Aim: Organisms primarily influence ecosystems through their functional traits when they are physically active. Following the nocturnal bottleneck, the expansion of mammals into the daytime expanded mammalian functional diversity (FD), however there is also notable overlap in trait space across diel niches leading to redundant FD. We explore how the unique and redundant contribution of each diel niche varies spatially and in relation to natural variation in light and temperature.

Location: Global.

Taxon: Extant mammals.

Methods: Based on five major functional traits (body mass, litter size, diet breadth, foraging strata, habitat breadth) for 5033 extant terrestrial mammals, we determine biogeographical variation in nocturnal, crepuscular, cathemeral and diurnal FD. We calculate the proportion of mammalian FD that is unique to each diel niche, and the proportion that is redundant across the daily cycle.

Results: The diversification of mammals into the daytime resulted in the creation of new FD (28.5% of FD is not nocturnal; Lower Quartile 17.3%; Upper Quartile 38.2%). Most of this expansion occurred at higher latitudes where uniquely cathemeral FD dominates (>55°N, 41.1% of mammalian FD; Lower Quartile 33.3%, Upper Quartile 53.6%), associated with fewer hours of biologically useful moonlight and daylight. Where there are more hours of biologically useful daylight, unique diurnal FD is common. However, more than half of non-nocturnal FD is redundant, increasing ecosystem stability as different species carry out similar functions at different times of day, and suggesting that many mammals have not diversified far from their nocturnal ancestors.

Main conclusions: Over much of the land surface more than a half of FD only occurs at night, underscoring the importance of nocturnal mammals for ecosystems. Understanding diel variation in FD not only informs on community structure and ecosystem function but also on ecosystem functional persistence in the Anthropocene, with pressures at night being particularly concerning.

Losing the natural night

Gaston, K.J., Gardner, A.S. & Cox, D.T.C. 2023. Anthropogenic changes to the nighttime environment. BioScience 73, 280-290.

How the relative impacts of anthropogenic pressures on the natural environment vary between different taxonomic groups, habitats, and geographic regions is increasingly well established. By contrast, the times of day at which those pressures are most forcefully exerted or have greatest influence are not well understood. The impact on the nighttime environment bears particular scrutiny, given that for practical reasons (e.g., researchers themselves belong to a diurnal species), most studies on the impacts of anthropogenic pressures are conducted during the daytime on organisms that are predominantly day active or in ways that do not differentiate between daytime and nighttime. In the present article, we synthesize the current state of knowledge of impacts of anthropogenic pressures on the nighttime environment, highlighting key findings and examples. The evidence available suggests that the nighttime environment is under intense stress across increasing areas of the world, especially from nighttime pollution, climate change, and overexploitation of resources. 

Shining a light on fear

Jolkkonen, J., Gaston, K.J. & Troscianko, J. 2023. Artificial lighting affects the landscape of fear in a widely distributed shorebird. Communications Biology 6, 131.

Fear influences almost all aspects of a prey species’ behaviour, such as its foraging and movement, and has the potential to cause trophic cascades. The superior low-light vision of many predators means that perceived predation risk in prey is likely to be affected by light levels. The widespread and increasing intensity of artificial light at night is therefore likely to interfere with this nocturnal visual arms race with unknown behavioural and ecological consequences. Here we test how the fear of predation perceived by wintering Eurasian curlew foraging on tidal flats is influenced by lighting. We quantified flight initiation distance (FID) of individuals under varying levels of natural and artificial illumination. Our results demonstrate that FID is significantly and substantially reduced at low light levels and increases under higher intensity illumination, with artificial light sources having a greater influence than natural sources. Contrary to the sensory-limitation hypothesis, the curlews’ unwillingness to take flight in low-light appears to reflect the risks posed by low-light flight, and a desire to remain on valuable foraging grounds. These findings demonstrate how artificial light can shape the landscape of fear, and how this interacts with optimal foraging decisions, and the costs of taking flight.

Making connections

Soga, M. & Gaston, K.J. 2023. Global synthesis reveals heterogeneous changes in connection of humans to nature. One Earth 6, 131-138.

The connection that individuals have with nature impacts their well-being and their support for pro-nature policies. While it is generally believed that the connection between humans and nature is decreasing, the extent of this trend is uncertain. Here, we present a global analysis of the temporal changes in people’s psychological and physical connections to nature. Using a systematic review protocol, we identified 71 articles consisting of 100 case studies. Most of these studies used cross-sectional, rather than longitudinal, approaches, which examine the connection to nature among people of different ages. The literature we reviewed indicates that there has been a decline in human connection to nature over time. However, the magnitude of changes in nature connection varied by geographic and socio-economic settings, with some studies showing an increasing trend. These findings suggest that there are opportunities to limit and reverse ongoing disconnection of humans from nature where it does occur.