Direct and indirect effects of light pollution on the performance of an herbivorous insect

Light pollution is a global disturbance with resounding impacts on a wide variety of organisms, but our understanding of these impacts is restricted to relatively few higher vertebrate species. We tested the direct effects of light pollution on herbivore performance as well as indirect effects mediated by host plant quality. We found that artificial light from streetlights alters plant toughness. Additionally, we found evidence of both direct and indirect effects of light pollution on the performance of an herbivorous insect, which indicates that streetlights can have cascading impacts on multiple trophic levels. Our novel findings suggest that light pollution can alter plant-insect interactions and thus may have important community-wide consequences.     

Red Sea corals under Artificial Light Pollution at Night (ALAN) undergo oxidative stress and photosynthetic impairment

Coral reefs represent the most diverse marine ecosystem on the planet, yet they are undergoing an unprecedented decline due to a combination of increasing global and local stressors. Despite the wealth of research investigating these stressors, Artificial Light Pollution at Night (ALAN) or “ecological light pollution” represents an emerging threat that has received little attention in the context of coral reefs, despite the potential of disrupting the chronobiology, physiology, behavior, and other biological processes of coral reef organisms. Scleractinian corals, the framework builders of coral reefs, depend on lunar illumination cues to synchronize their biological rhythms such as behavior, reproduction and physiology. While, light pollution (POL) may mask and lead de‐synchronization of these biological rhythms process. To reveal if ALAN impacts coral physiology, we have studied two coral species, Acropora eurystoma and Pocillopora damicornis, from the Gulf of Eilat/Aqaba, Red Sea, which is undergoing urban development that has led to severe POL at night. Our two experimental design data revealed that corals exposed to ALAN face an oxidative stress condition, show lower photosynthesis performances measured by electron transport rate (ETR), as well as changes in chlorophyll and algae density parameters. Testing different lights such as Blue LED and White LED spectrum showed more extreme impact in comparison to Yellow LEDs on coral physiology. The finding of this work sheds light on the emerging threat of POL and the impacts on the biology and ecology of Scleractinian corals, and will help to formulate specific management implementations to mitigate its potentially harmful impacts.     

Light pollution may create demographic traps for nocturnal insects

Light pollution impacts both intra- and inter-specific interactions, such as interactions between mates and predator–prey interactions. In mobile organisms attracted to artificial lights, the effect of light pollution on these interactions may be intensified. If organisms are repelled by artificial lights, effects of light pollution on intra- and inter-specific interactions may be diminished as organisms move away. However, organisms repelled by artificial lights would likely lose suitable habitat as light pollution expands. Thus, we investigated how light pollution affects both net attraction or repulsion of organisms and effects on intra- and inter-specific interactions. In manipulative field studies using fireflies, we found that Photuris versicolor and Photinus pyralis fireflies were lured to artificial (LED) light at night and that both species were less likely to engage in courtship dialogues (bioluminescent flashing) in light-polluted field plots. Light pollution also lowered the mating success of P. pyralis. P. versicolor is known to prey upon P. pyralis by mimicking the flash patterns of P. pyralis, but we did not find an effect of light pollution on Photuris–Photinus predator–prey interactions. Our study suggests, that for some nocturnal insects, light-polluted areas may act as demographic traps, i.e., areas where immigration exceeds emigration and inhibition of courtship dialogues and mating reduces reproduction. Examining multiple factors affecting population growth in concert is needed to understand and mitigate impacts of light pollution on wildlife.     

Overseas seed dispersal by migratory birds

Long-distance dispersal (LDD) promotes the colonization of isolated and remote habitats, and thus it has been proposed as a mechanism for explaining the distributions of many species. Birds are key LDD vectors for many sessile organisms such as plants, yet LDD beyond local and regional scales has never been directly observed nor quantified. By sampling birds caught while in migratory flight by GPS-tracked wild falcons, we show that migratory birds transport seeds over hundreds of kilometres and mediate dispersal from mainland to oceanic islands. Up to 1.2% of birds that reached a small island of the Canary Archipelago (Alegranza) during their migration from Europe to Sub-Saharan Africa carried seeds in their guts. The billions of birds making seasonal migrations each year may then transport millions of seeds. None of the plant species transported by the birds occurs in Alegranza and most do not occur on nearby Canary Islands, providing a direct example of the importance of environmental filters in hampering successful colonization by immigrant species. The constant propagule pressure generated by these LDD events might, nevertheless, explain the colonization of some islands. Hence, migratory birds can mediate rapid range expansion or shifts of many plant taxa and determine their distribution.     

Why artificial light at night should be a focus for global change research in the 21st century

The environmental impacts of artificial light at night have been a rapidly growing field of global change science in recent years. Yet, light pollution has not achieved parity with other global change phenomena in the level of concern and interest it receives from the scientific community, government and nongovernmental organizations. This is despite the globally widespread, expanding and changing nature of night‐time lighting and the immediacy, severity and phylogenetic breath of its impacts. In this opinion piece, we evidence 10 reasons why artificial light at night should be a focus for global change research in the 21st century. Our reasons extend beyond those concerned principally with the environment, to also include impacts on human health, culture and biodiversity conservation more generally. We conclude that the growing use of night‐time lighting will continue to raise numerous ecological, human health and cultural issues, but that opportunities exist to mitigate its impacts by combining novel technologies with sound scientific evidence. The potential gains from appropriate management extend far beyond those for the environment, indeed it may play a key role in transitioning towards a more sustainable society.     

Migratory Disturbance Thresholds with Mule Deer and Energy Development

Fine-scale movement data has transformed our knowledge of ungulate migration ecology and now provides accurate, spatially explicit maps of migratory routes that can inform planning and management at local, state, and federal levels. Among the most challenging land use planning issues has been developing energy resources on public lands that overlap with important ungulate habitat, including the migratory routes of mule deer (Odocoileus hemionus). We generally know that less development is better for minimizing negative effects and maintaining habitat function, but we lack information on the amount of disturbance that animals can tolerate before reducing use of or abandoning migratory habitat. We used global positioning system data from 56 deer across 15 years to evaluate how surface disturbance from natural gas well pads and access roads in western Wyoming, USA, affected habitat selection of mule deer during migration and whether any disturbance threshold(s) existed beyond which use of migratory habitat declined. We used resource and step selection functions to examine disturbance thresholds at 3 different spatial scales. Overall, migratory use by mule deer declined as surface disturbance increased. Based on the weight of evidence from our 3 independent but complementary metrics, declines in migratory use related to surface disturbance were non-linear, where migratory use sharply declined when surface disturbance from energy development exceeded 3%. Disturbance thresholds may vary across regions, species, or migratory habitats (e.g., stopover sites). Such information can help with management and land use decisions related to mineral leasing and energy development that overlap with the migratory routes of ungulates. © 2020 The Wildlife Society.     

A latent threat to biodiversity: consequences of small-scale heterogeneity loss

The threat of homogenisation to biodiversity is generally considered to occur at broad scales or in response to high-intensity impacts. Therefore, most biodiversity studies estimate local average or total species richness rather than local heterogeneity. Here we consider the potential for relative shifts between these different aspects of biodiversity at small spatial scales to be an early warning signal for biodiversity loss. In response to chronic, very low-level pollution, we observed a disjunctive response with gamma diversity (total species richness) and beta diversity (heterogeneity) decreasing while alpha diversity (average species richness) was still increasing. Homogenisation may, therefore, affect biodiversity through thresholds that alter the relationship between the average species richness and its heterogeneity, leading to the potential for regime shifts. Our stressor also had a strong negative effect on rare species, meaning that the purported importance of rare species as “insurance” in the face of environmental change may be overstated.     

微塑料污染对浮游生物影响研究进展

微塑料作为一种新型的环境污染物,大量存在于水环境中,给水生生物带来了极大的危害。浮游生物是水生食物链的基础,是水生生态系统物质循环和能量流动的重要环节;同时,浮游生物也是对各种环境污染物最敏感的类群。了解微塑料对浮游生物的影响是评价其生态风险的重要依据。本文介绍了环境中微塑料来源、特征及水生态系统微塑料污染现状,阐述了微塑料对水生生物的直接和间接危害,并重点聚焦于浮游植物和浮游动物,从个体、种群和群落的层次详细总结了微塑料的影响及其作用机制。最后,本文指出当前针对浮游生物微观基因和蛋白质组学,以及宏观种群和群落响应等方面的研究还非常缺乏,为今后开展微塑料危害研究提供参考。     

Emerging threat of the 21st century lightscape to global biodiversity

Over the last century the temporal and spatial distribution of light on Earth has been drastically altered by human activity. Despite mounting evidence of detrimental effects of light pollution on organisms and their trophic interactions, the extent to which light pollution threatens biodiversity on a global scale remains unclear. We assessed the spatial extent and magnitude of light encroachment by measuring change in the extent of light using satellite imagery from 1992 to 2012 relative to species richness for terrestrial and freshwater mammals, birds, reptiles, and amphibians. The encroachment of light into previously dark areas was consistently high, often doubling, in areas of high species richness for all four groups. This pattern persisted for nocturnal groups (e.g., bats, owls, and geckos) and species considered vulnerable to extinction. Areas with high species richness and large increases in light extent were clustered within newly industrialized regions where expansion of light is likely to continue unabated unless we act to conserve remaining darkness. Implementing change at a global scale requires global public, and therefore scientific, support. Here, we offer substantial evidence that light extent is increasing where biodiversity is high, representing an emerging threat to global biodiversity requiring immediate attention.     

Light Pollution Modifies the Expression of Daily Rhythms and Behavior Patterns in a Nocturnal Primate

Among anthropogenic pressures, light pollution altering light/dark cycles and changing the nocturnal component of the environment constitutes a threat for biodiversity. Light pollution is widely spread across the world and continuously growing. However, despite the efforts realized to describe and understand the effects of artificial lighting on fauna, few studies have documented its consequences on biological rhythms, behavioral and physiological functions in nocturnal mammals. To determine the impacts of light pollution on nocturnal mammals an experimental study was conducted on a nocturnal primate, the grey mouse lemur Microcebus murinus. Male mouse lemurs (N = 8) were exposed 14 nights to moonlight treatment and then exposed 14 nights to light pollution treatment. For both treatments, chronobiological parameters related to locomotor activity and core temperature were recorded using telemetric transmitters. In addition, at the end of each treatment, the 14^th night, nocturnal and feeding behaviors were explored using an infrared camera. Finally, throughout the study, body mass and daily caloric food intake were recorded. For the first time in a nocturnal primate, light pollution was demonstrated to modify daily rhythms of locomotor activity and core temperature especially through phase delays and increases in core temperature. Moreover, nocturnal activity and feeding behaviors patterns were modified negatively. This study suggests that light pollution induces daily desynchronization of biological rhythms and could lead to seasonal desynchronization with potential deleterious consequences for animals in terms of adaptation and anticipation of environmental changes.     

Microplastics as an emerging threat to terrestrial ecosystems

Microplastics (plastics <5 mm, including nanoplastics which are <0.1 μm) originate from the fragmentation of large plastic litter or from direct environmental emission. Their potential impacts in terrestrial ecosystems remain largely unexplored despite numerous reported effects on marine organisms. Most plastics arriving in the oceans were produced, used, and often disposed on land. Hence, it is within terrestrial systems that microplastics might first interact with biota eliciting ecologically relevant impacts. This article introduces the pervasive microplastic contamination as a potential agent of global change in terrestrial systems, highlights the physical and chemical nature of the respective observed effects, and discusses the broad toxicity of nanoplastics derived from plastic breakdown. Making relevant links to the fate of microplastics in aquatic continental systems, we here present new insights into the mechanisms of impacts on terrestrial geochemistry, the biophysical environment, and ecotoxicology. Broad changes in continental environments are possible even in particle‐rich habitats such as soils. Furthermore, there is a growing body of evidence indicating that microplastics interact with terrestrial organisms that mediate essential ecosystem services and functions, such as soil dwelling invertebrates, terrestrial fungi, and plant‐pollinators. Therefore, research is needed to clarify the terrestrial fate and effects of microplastics. We suggest that due to the widespread presence, environmental persistence, and various interactions with continental biota, microplastic pollution might represent an emerging global change threat to terrestrial ecosystems.     

The genetics of migration on the move

Across a range of organisms, related species or even populations of the same species exhibit strikingly different scales and patterns of movement. A significant proportion of the phenotypic variance in migratory traits is genetic, but the genes involved in shaping these phenotypes are still unknown. Although recent achievements in genomics will evolve migratory genetics research from a phenotypic to a molecular approach, fully sequenced and annotated genomes of migratory species are still lacking. Consequently, many of the genes involved in migration are unavailable as candidates. Migration is central to the life-history adaptations of many animals. Here, we review current understanding of the genetic architecture of migratory traits and discuss the significant implications this will have for other areas of biology, including population responses to climate change, speciation and conservation management.     

Long‐term effects of artificial nighttime lighting and trophic complexity on plant biomass and foliar carbon and nitrogen in a grassland community

The introduction of artificial nighttime lighting due to human settlements and transport networks is increasingly altering the timing, intensity, and spectra of natural light regimes worldwide. Much of the research on the impacts of nighttime light pollution on organisms has focused on animal species. Little is known about the impacts of daylength extension due to outdoor lighting technologies on wild plant communities, despite the fact that plant growth and development are under photoperiodic control. In a five‐year field experiment, artificial ecosystems (“mesocosms”) of grassland communities both alone or in combination with invertebrate herbivores and predators were exposed to light treatments that simulated street lighting technologies (low‐pressure sodium, and light‐emitting diode [LED]‐based white lighting), at ground‐level illuminance. Most of the plant species in the mesocosms did not exhibit changes in biomass accumulation after 5 years of exposure to the light treatments. However, the white LED treatment had a significant negative effect on biomass production in the herbaceous species Lotus pedunculatus. Likewise, the interaction between the white LED treatment and the presence of herbivores significantly reduced the mean shoot/root ratio of the grass species Holcus lanatus. Artificial nighttime lighting had no effect on the foliar carbon or nitrogen in most of the grassland species. Nevertheless, the white LED treatment significantly increased the leaf nitrogen content in Lotus corniculatus in the presence of herbivores. Long‐term exposure to artificial light at night had no general effects on plant biomass responses in experimental grassland communities. However, species‐specific and negative effects of cool white LED lighting at ground‐level illuminance on biomass production and allocation in mixed plant communities are suggested by our findings. Further studies on the impacts of light pollution on biomass accumulation in plant communities are required as these effects could be mediated by different factors, including herbivory, competition, and soil nutrient availability.     

The matter of spatial and temporal scales: a review of reindeer and caribou response to human activity

Research on impacts of human activity and infrastructure development on reindeer and caribou (Rangifer tarandus) is reviewed in the context of spatial (m to many km) and temporal (min to decades) scales. Before the 1980s, most disturbance studies were behavioral studies of individual animals at local scales, reporting few and short-term (min to h) impacts within 0–2 km from human activity. Around the mid 1980s, focus shifted to regional-scale landscape studies, reporting that Rangifer reduced the use of areas within 5 km from infrastructure and human activity by 50–95% for weeks, months or even years and increased use of remaining undisturbed habitat far beyond those distances. The extent could vary with type of disturbance, sex, terrain, season, and sensitivity of herds. Of 85 studies reviewed, 83% of the regional studies concluded that the impacts of human activity were significant, while only 13% of the local studies did the same. Accurate assessment of impacts from human activity requires regional-scale studies, a pattern confirmed in a few long-term (decades) pre- and post-development studies. Such long-term studies are needed to improve understanding of both temporal and spatial patterns.     

Application of IUCN Red Listing Criteria at the Regional and National Levels: A Case Study from Central Asia

We assessed the threatened status of 163 Central Asian vertebrates using the IUCN Red List Criteria (Version 3.1) at the national and regional levels, and compared these assessments to the global assessments given in the IUCN 2002 Red List. We thus compared threat status at three spatial scales; national for five countries separately (Kazakhstan, Kyrgyzstan, Tadjikistan, Turkmenistan, Uzbekistan), regional for the five countries together, and global. This analysis was undertaken as a test of the applicability of IUCN criteria at the sub-global level. Generally the criteria worked well. In 4% of cases, the threat category was lower at the smaller scale of assessment. This was predominately caused by the use of decline rate criteria at the larger scale when populations at the smaller scale were stable. We also encountered issues with the listing of migratory species at the sub-global level. We used our data to carry out a preliminary assessment of Protected Area coverage in the region, and found evidence suggesting that threatened species and endemics are not well covered by the current protected area system.     

Understanding Oceanic Migrations with Intrinsic Biogeochemical Markers

Migratory marine vertebrates move annually across remote oceanic water masses crossing international borders. Many anthropogenic threats such as overfishing, bycatch, pollution or global warming put millions of marine migrants at risk especially during their long-distance movements. Therefore, precise knowledge about these migratory movements to understand where and when these animals are more exposed to human impacts is vital for addressing marine conservation issues. Because electronic tracking devices suffer from several constraints, mainly logistical and financial, there is emerging interest in finding appropriate intrinsic markers, such as the chemical composition of inert tissues, to study long-distance migrations and identify wintering sites. Here, using tracked pelagic seabirds and some of their own feathers which were known to be grown at different places and times within the annual cycle, we proved the value of biogeochemical analyses of inert tissue as tracers of marine movements and habitat use. Analyses of feathers grown in summer showed that both stable isotope signatures and element concentrations can signal the origin of breeding birds feeding in distinct water masses. However, only stable isotopes signalled water masses used during winter because elements mainly accumulated during the long breeding period are incorporated into feathers grown in both summer and winter. Our findings shed new light on the simple and effective assignment of marine organisms to distinct oceanic areas, providing new opportunities to study unknown migration patterns of secretive species, including in relation to human-induced mortality on specific populations in the marine environment.     

Pesticide alters oviposition site selection in gray treefrogs

Understanding the impacts of pesticides on non-target organisms is an important issue for conservation biology. Research into the environmental consequences of pesticides has largely focused on pesticide toxicity. We have less understanding of the nonlethal effects of pesticides, and the consequences of nonlethal effects for species and communities. For example, we know very little about whether pesticides alter habitat selection behavior. Understanding whether pesticides alter habitat selection is important because pesticide-induced shifts in habitat selection could either magnify or reduce the toxic effects of contaminants by funneling organisms into or directing them away from contaminated sites. Here we present four field experiments that examine the effect of the commercial pesticide Sevin and its active ingredient, carbaryl, on oviposition site selection by the gray treefrog (Hyla chrysoscelis). Our results show that uncontaminated pools consistently received 2-3 times more eggs than contaminated pools; that treefrogs appeared to respond to Sevin directly, not indirectly via its effects on the aquatic food web, and that this preference persisted across a range of temporal and spatial scales. Both Sevin and carbaryl per se reduced oviposition, while other volatile chemicals (e.g., our solvent control, acetone) had no effect. These findings suggest that in order to understanding the consequences of contaminants in aquatic systems we will need to consider not only toxicity, but also how contaminant effects on habitat selection alter the way organisms distribute themselves in the environment.     

Sex‐biases in distribution and resource use at different spatial scales in a migratory shorebird

In migratory species, sexual size dimorphism can mean differing energetic requirements for males and females. Differences in the costs of migration and in the environmental conditions occurring throughout the range may therefore result in sex‐biases in distribution and resource use at different spatial scales. In order to identify the scale at which sexual segregation operates, and thus the scale at which environmental changes may have sex‐biased impacts, we use range‐wide tracking of individually color‐ringed Icelandic black‐tailed godwits (Limosa limosa islandica) to quantify sexual segregation at scales ranging from the occupation of sites throughout the non‐breeding range to within‐site differences in distribution and resource use. Throughout the range of this migratory shorebird, there is no evidence of large‐scale sex differences in distribution during the non‐breeding season. However, the sexes differ in their selection of prey types and sizes, which results in small‐scale sexual segregation within estuaries. The scale of sexual segregation therefore depends on the scale of variation in resource distribution, which, in this system, is primarily within estuaries. Sexual segregation in within‐site distribution and resource use means that local‐scale anthropogenic impacts on estuarine benthic prey communities may disproportionately affect the sexes in these migratory shorebirds.     

The effects of light characteristics on avian mortality at lighthouses

The generation of artificial light by human activity can have far-reaching detrimental impacts upon a wide variety of organisms. A great deal of attention has been paid to well-lit buildings, television towers, and communication towers as sources of mortality for nocturnally migrating songbirds. However, despite being among the first human structures known to generate migratory bird kills, little is known about the current impact of lighthouses on birds, or the impact of light design. We examined the impact of a lighthouse on nocturnal avian migrants at Long Point, Lake Erie, Ontario, Canada. From 1960–1989, mean annual kills were 200 birds in spring, and 393 in autumn, with kills of up to 2000 birds in a single night. In 1989, the Long Point lighthouse was automated, with a simultaneous change in beam characteristics – the new beam is narrower and less powerful. This change brought about a drastic reduction in avian mortality at the lighthouse to a mean of only 18.5 birds per year in spring, and 9.6 in autumn from 1990–2002. Our results highlight the effectiveness of simple changes in light signatures in reducing avian light attraction and mortality during migration.