Abstract: The scale and extent of global urbanization are unprecedented and increasing. As urbanization generally encroaches on natural habitats and the urban ecological footprint reaches far beyond the city limits, how urbanization affects biodiversity has received increasing attention from the scientific community. Nonetheless, the comprehensive syntheses of urbanization consequences for biodiversity, including diverse taxonomic groups, across multiple spatial scales and spanning a wide gradient range of urbanization intensity are still insufficient. Here, based on the urban-rural gradient approach, we assessed the effects of urbanization on Chinese mammal and amphibian richness across the entire urbanization gradient (i.e., urbanization level from 0 to 1) at the national, regional and urban agglomeration scales. We used the global mammal and amphibian distribution data along with corresponding background climate, habitat conditions and socioeconomic activities data for analysis. Our results revealed a detailed and diverse pattern of Chinese mammal and amphibian richness along the entire spectrum of urbanization gradient across three spatial scales. And an approximately monotonic decrease only existed in certain urban agglomerations. The imprint of urbanization on mammal and amphibian richness were largely masked by the overall primacy of background climate at the national and regional scales. As the scale of analysis shifting from the country to urban agglomerations, urbanization-associated variables and locally specific limiting factors started to play important roles in driving the richness patterns. Moreover, the environmental Kuznets curve hypothesis can explain the relationship between biodiversity pressure and urbanization activities in certain Chinese urban agglomerations. However, the findings of urbanization effects on biodiversity using the urban-rural gradient analysis should be interpreted with caution because many possible driving forces simultaneously present along the urban-rural gradient and are very challenging to attribute.
Keywords: Animals; Remote Sensing
Abstract: Seasonal changes in the natural light condition play a pivotal role in the regulation of many biological processes in organisms. Disruption of this natural condition via the growing loss of darkness as a result of anthropogenic light pollution has been linked to species-wide shifts in behavioral and physiological traits. This review starts with a brief overview of the definition of light pollution and the most recent insights into the perception of light. We then go on to review the evidence for some adverse effects of ecological light pollution on different groups of animals and will focus on mollusks. Taken together, the available evidence suggests a critical role for light pollution as a recent, growing threat to the regulation of various biological processes in these animals, with the potential to disrupt ecosystem stability. The latter indicates that ecological light pollution is an environmental threat that needs to be taken seriously and requires further research attention.
Keywords: Animals; Artificial light; Biorhythm; Mollusca; Reproduction; Slugs; Snails; Zeitgeber
Abstract: Growth and survival of larval fishes is highly variable and unpredictable. Our limited understanding of this variation constrains our ability to forecast population dynamics and effectively manage fisheries. Here we show that daily growth rates of a coral reef fish (the sixbar wrasse, Thalassoma hardwicke) are strongly lunar-periodic and predicted by the timing of nocturnal brightness: growth was maximized when the first half of the night was dark and the second half of the night was bright. Cloud cover that obscured moonlight facilitated a 'natural experiment', and confirmed the effect of moonlight on growth. We suggest that lunar-periodic growth may be attributable to light-mediated suppression of diel vertical migrations of predators and prey. Accounting for such effects will improve our capacity to predict the future dynamics of marine populations, especially in response to climate-driven changes in nocturnal cloud cover and intensification of artificial light, which could lead to population declines by reducing larval survival and growth.
Abstract: Sleep is a critically important behaviour for all mammals due to its fundamental role within homeostatic/circadian systems and memory consolidation. As a large and vigilant prey species that is highly sensitive to stimuli at night, the horse sleeps less than other mammalian species. For this reason, the domestic environment has the potential to greatly affect the duration and quality of equine sleep. This study aimed to determine the effect of environmental factors on equine sleep stages, and whether this would influence cognitive performance during a spatial memory task. Ten riding school horses (mixed breed/ height/ sex; average age 14.9 + 2.4 years) were randomly assigned to two groups (n = 5) within a five-week crossover repeated measures design experiment. Each group experienced a combination of one of two light conditions (lights on = Treatment; lights off = Control), and one of two bedding depth treatments (15 cm bed = control; 5 cm bed = treatment) for six days. Duration of sleep stage behaviours (standing Non-Rapid Eye Movement [NREM]), sternal NREM, sternal Rapid Eye Movement [REM] and lateral REM) were measured continuously using CCTV infrared cameras. For the spatial memory task, latency, number of correct responses, and differences between these parameters during training and testing days were measured. A repeated measures general linear model assessed the effects of treatment conditions on duration of sleep stage, and changes in sleep stage over time (bedding and light set as within-subject factors). Wilcoxon Signed-Rank and paired t-tests determined differences in memory task parameters between treatments. Comparing Treatment Bedding with Control Bedding conditions, horses spent on average significantly less time in lateral REM (0.34 ± 0.12 versus 0.46 ± 0.13 hrs; p = 0.032) and sternal NREM (0.64 ± 0.10 versus 0.80 ± 0.12 hrs; p = 0.007), and significantly more time in standing NREM (3.69 ± 0.76 versus 3.17 ± 0.77; p = 0.024). Only sternal REM was significantly affected during the Treatment Light condition compared to control conditions (0.53 ± 0.07 versus 0.67 ± 0.11; p = 0.031). Interactions between day and treatment were apparent for specific sleep stage behaviours indicative of acclimatisation. No significant effects (p > 0.05) of Treatment Light or Bedding conditions were detected for performance during the spatial memory test. Overall, horses exposed to sub-optimal conditions tended to display significantly less time in recumbent sleep stages (NREM and REM) and increased time in a standing NREM stage. The impact of reduced sleep on equine cognition requires further study.
Keywords: Animals
Abstract: The present review draws together wide-ranging studies performed over the last decades that catalogue the effects of artificial-light-at-night (ALAN) upon living species and their environment. We provide an overview of the tremendous variety of light-detection strategies which have evolved in living organisms – unicellular, plants and animals, covering chloroplasts (plants), and the plethora of ocular and extra-ocular organs (animals). We describe the visual pigments which permit photo-detection, paying attention to their spectral characteristics, which extend from the ultraviolet into infrared. We discuss how organisms use light information in a way crucial for their development, growth and survival: phototropism, phototaxis, photoperiodism, and synchronization of circadian clocks. These aspects are treated in depth, as their perturbation underlies much of the disruptive effects of ALAN. The review goes into detail on circadian networks in living organisms, since these fundamental features are of critical importance in regulating the interface between environment and body. Especially, hormonal synthesis and secretion are often under circadian and circannual control, hence perturbation of the clock will lead to hormonal imbalance. The review addresses how the ubiquitous introduction of light-emitting diode technology may exacerbate, or in some cases reduce, the generalized ever-increasing light pollution. Numerous examples are given of how widespread exposure to ALAN is perturbing many aspects of plant and animal behaviour and survival: foraging, orientation, migration, seasonal reproduction, colonization and more. We examine the potential problems at the level of individual species and populations and extend the debate to the consequences for ecosystems. We stress, through a few examples, the synergistic harmful effects resulting from the impacts of ALAN combined with other anthropogenic pressures, which often impact the neuroendocrine loops in vertebrates. The article concludes by debating how these anthropogenic changes could be mitigated by more reasonable use of available technology – for example by restricting illumination to more essential areas and hours, directing lighting to avoid wasteful radiation and selecting spectral emissions, to reduce impact on circadian clocks. We end by discussing how society should take into account the potentially major consequences that ALAN has on the natural world and the repercussions for ongoing human health and welfare.