Abstract: The growth in human population along coastal areas is exposing marine environments to increasing anthropogenic light sources. Despite the potential effects of this modern phenomenon, very few studies have examined its implications for corals. Here, we present a long-term study of coral early life stages under light pollution conditions at night. Coral larvae were collected from Stylophora pistillata colonies, and then settled and grown under experimental conditions of two different common city lighting methods (fluorescent or LED). Effects of the artificial lighting on the coral settlement success, survivorship, growth rate, photosynthetic efficiency, and calcification rate were examined over a period of one year. The control exhibited ~30% higher settlement success compared to the two light treatments, while under the light treatments corals showed higher survivorship, growth, and calcification rates. In addition, an indication of damage to the photosynthetic system was found in the light-polluted corals, which was reflected in their photosynthesis efficiency parameters: i.e., lower maximum light utilization coefficient (alpha), lower maximum potential photosynthetic rate (Pmax), and lower photosynthetic maximal quantum yield (Fv/Fm). Our findings provide evidence of the potential adverse effects of artificial lighting methods on the natural environment of coral reefs. We conclude that the use of the LED lighting method has high interference potential for the early life stages of corals.
Abstract: Change in day length is an important cue for reproductive activation in seasonally breeding animals to ensure that the timing of greatest maternal investment (e.g. lactation in mammals) coincides with favourable environmental conditions (e.g. peak productivity). However, artificial light at night has the potential to interfere with the perception of such natural cues. Following a 5-year study on two populations of wild marsupial mammals exposed to different night-time levels of anthropogenic light, we show that light pollution in urban environments masks seasonal changes in ambient light cues, suppressing melatonin levels and delaying births in the tammar wallaby. These results highlight a previously unappreciated relationship linking artificial light at night with induced changes in mammalian reproductive physiology, and the potential for larger-scale impacts at the population level.
Abstract: Many marine ecosystems are shaped by regimes of natural light guiding the behavior of their constituent species. As evidenced from terrestrial systems, the global introduction of nighttime lighting is likely influencing these behaviors, restructuring marine ecosystems, and compromising the services they provide. Yet the extent to which marine habitats are exposed to artificial light at night is unknown. We quantified nighttime artificial light across the world's network of marine protected areas (MPAs). Artificial light is widespread and increasing in a large percentage of MPAs. While increases are more common among MPAs associated with human activity, artificial light is encroaching into a large proportion of even those marine habitats protected with the strongest legislative designations. Given the current lack of statutory tools, we propose that allocating “Marine Dark Sky Park†status to MPAs will help incentivize responsible authorities to hold back the advance of artificial light.
Abstract: As human populations continue to expand, many more species are affected by habitat fragmentation and urbanization. One of the most common themes in studies of fragmented habitats is finding higher rates of predation along habitat edges. However, field studies supporting this pattern are heavily influenced by avian literature and may not apply similarly to other organisms, such as invertebrates. Field studies of predation are typically performed during the day or do not distinguish between day and night; these studies therefore overlook daily fluctuations in predation and may miss important effects that occur solely at night, such as light pollution from streetlights. We tested whether predation of larval Lepidoptera differed between edge and core habitats and also whether predation along the habitat edge varied in response to light pollution from streetlights. We placed larvae in the core of suburban habitat patches and along the habitat edge, both under streetlights as well as between streetlights where it was dark. We found that predation rate increased in both edge and core habitats over the summer. Early season, we found daily fluctuations in predation dynamics with greater predation along the habitat edge than in the habitat core during the day, but not at night. Additionally, we found that streetlights did not affect predation rate along the habitat edge. Our results suggest that increased predation along habitat edges may be a diurnal effect.
Abstract: Marine benthic communities face multiple anthropogenic pressures that compromise the future of some of the most biodiverse and functionally important ecosystems in the world. Yet one of the pressures these ecosystems face, night-time lighting, remains unstudied. Light is an important cue in guiding the settlement of invertebrate larvae, and altering natural regimes of nocturnal illumination could modify patterns of recruitment among sessile epifauna. We present the first evidence of night-time lighting changing the composition of temperate epifaunal marine invertebrate communities. Illuminating settlement surfaces with white light-emitting diode lighting at night, to levels experienced by these communities locally, both inhibited and encouraged the colonization of 39% of the taxa analysed, including three sessile and two mobile species. Our results indicate that ecological light pollution from coastal development, shipping and offshore infrastructure could be changing the composition of marine epifaunal communities.