scholarly journals Light Pollution, Circadian Photoreception, and Melatonin in Vertebrates

2019 ◽  
Vol 11 (22) ◽  
pp. 6400 ◽  
Author(s):  
Maja Grubisic ◽  
Abraham Haim ◽  
Pramod Bhusal ◽  
Davide M. Dominoni ◽  
Katharina M. A. Gabriel ◽  
...  
Keyword(s):  
High Sensitivity ◽  
Mitigation Strategies ◽  
Light Pollution ◽  
Natural Ecosystems ◽  
Melatonin Suppression ◽  
Light Levels ◽  
Rigorous Testing ◽  
Crucial Information ◽  
Lower Light ◽  
Available Information

Artificial light at night (ALAN) is increasing exponentially worldwide, accelerated by the transition to new efficient lighting technologies. However, ALAN and resulting light pollution can cause unintended physiological consequences. In vertebrates, production of melatonin—the “hormone of darkness” and a key player in circadian regulation—can be suppressed by ALAN. In this paper, we provide an overview of research on melatonin and ALAN in vertebrates. We discuss how ALAN disrupts natural photic environments, its effect on melatonin and circadian rhythms, and different photoreceptor systems across vertebrate taxa. We then present the results of a systematic review in which we identified studies on melatonin under typical light-polluted conditions in fishes, amphibians, reptiles, birds, and mammals, including humans. Melatonin is suppressed by extremely low light intensities in many vertebrates, ranging from 0.01–0.03 lx for fishes and rodents to 6 lx for sensitive humans. Even lower, wavelength-dependent intensities are implied by some studies and require rigorous testing in ecological contexts. In many studies, melatonin suppression occurs at the minimum light levels tested, and, in better-studied groups, melatonin suppression is reported to occur at lower light levels. We identify major research gaps and conclude that, for most groups, crucial information is lacking. No studies were identified for amphibians and reptiles and long-term impacts of low-level ALAN exposure are unknown. Given the high sensitivity of vertebrate melatonin production to ALAN and the paucity of available information, it is crucial to research impacts of ALAN further in order to inform effective mitigation strategies for human health and the wellbeing and fitness of vertebrates in natural ecosystems.

Biological effects of low-intensity radiofrequency fields and risk assessment for biota

2020 ◽  
Vol 60 (9) ◽  
pp. 592-596
Author(s):  
Elena I. Sarapultseva ◽  
Darya V. Uskalova ◽  
Ksenya V. Ustenko
Keyword(s):  
Radio Frequency ◽  
Electromagnetic Radiation ◽  
Electromagnetic Fields ◽  
Negative Impact ◽  
Biological Effects ◽  
High Sensitivity ◽  
Communication Technologies ◽  
Natural Ecosystems ◽  
Low Intensity ◽  
Different Levels

Despite the fact that there are still conflicting opinions about the damage caused by modern wireless communication technologies, most scientists report on the negative biological effects of low-intensity radio frequency electromagnetic radiation at different levels of the organization of live nature. There is no doubt that there is a need not only for a sanitary and hygienic assessment of man-made electromagnetic effects on humans, but also for an environmental assessment for biota. The purpose of the study was to assess the potential environmental risk of electromagnetic impact in the centimeter range on natural ecosystems. The initial data were the authors' own results in the field of radiobiology of non-ionizing radiation, as well as published of other researchers. The article analyzes the biological effects of radio frequency electromagnetic fields detected in organisms of different systematic groups and levels of organization. The data on the non-thermal biological effects of electromagnetic fields indicate a high sensitivity of different species to this factor. The analyzed research results emphasize the need to take into account the features of non-thermal effects of electromagnetic radiation on biota, since these radiations can have a negative impact on different hierarchical levels in natural ecosystems.

scholarly journals Tall Wheatgrass (Thinopyrum ponticum): Flood Resilience, Growth Response to Sea Water Immersion, and Its Capacity for Erosion and Flooding Control of Coastal Areas

Environments ◽  
2019 ◽  
Vol 6 (9) ◽  
pp. 103
Author(s):  
Stoyan Vergiev
Keyword(s):  
Growth Response ◽  
Sea Water ◽  
Oxygen Deficiency ◽  
Water Immersion ◽  
Coastal Zone Management ◽  
Mitigation Strategies ◽  
Natural Ecosystems ◽  
Thinopyrum Ponticum ◽  
Zone Management ◽  
Tall Wheatgrass

Integrated coastal zone management proposes nature-based mitigation strategies based on the replacement of artificial coastal stabilization and protection structures with dunes stabilized with plant species. These psammophytes stabilize sands and act as supporters, increasing dunes’ ability to reduce storm damages and effectively minimize erosion with minimal negative impacts to natural ecosystems. That is why searching for native salt-tolerant plants with extensive root systems and studying their capacity for erosion and flooding control is fundamental to the practice of ecologically-sound ecosystem services. The aim of the present study is to define the effects of flooding stress on a number of wheatgrass (Thinopyrum ponticum) plant life aspects (survival ability, viability, and growth response) in order to determine wheatgrass’s capacity as dune stabilizer. Conducted experiments established that T. ponticum was very tolerant to immersion impact and salt and oxygen deficiency stress, and its rhizomes were able to regenerate after 30 days in seawater. The temporal expression of its survival is presented as critical decomposition time (CDT) by linking the maximum duration of floods along the Bulgarian Black Sea Coast and the resilience of tall wheatgrass in flooding simulations. A statistical analysis of the experimental data demonstrated that immersion in sea water increases rhizome viability, biomass, and allocation to root biomass, whereas other factors, such as the duration of immersion, salinity, and temperatures of sea water have no significant effect. According to flood resilience and growth response to sea water submergence, T. ponticum demonstrated high potential to be a dune stabilizer.

Determination of spikelet number in wheat. II.* Effect of varying light level on ear development

1977 ◽  
Vol 28 (4) ◽  
pp. 575 ◽  
Author(s):  
MS Rahman ◽  
JH Wilson ◽  
Y Aitken
Keyword(s):  
Light Level ◽  
Floral Initiation ◽  
Wheat Cultivars ◽  
Spikelet Number ◽  
Rate Of Development ◽  
Light Levels ◽  
Two Factors ◽  
Lower Light ◽  
Ear Number

The effects of two light levels (0.98 and 4.90 cal cm-2 hr-1) on rate of development and spikelet number per ear were studied in eight wheat cultivars grown under a 16 hr photoperiod at 20°C. The objective was to ascertain how light affects spikelet number. At the lower light level the durations of the vegetative, spikelet and ear elongation phases were greater, but the number of spikelets per ear, number of phytomers present at floral initiation, final leaf number, number of phytomers that were converted into spikelets, apex length at floral initiation and rate of spikelet initiation were smaller than at the higher light level. Responses to varying light level for a11 these parameters were similar for different cultivars, but the sizes of the responses differed. Within a given cultivar, an increase in spikelet number was associated with longer apices at floral initiation and a higher rate of spikelet initiation. It was concluded that these two factors are important determinants of spikelet number. ___________________ *Part I, Aust. J. Agric, Res., 28: 565 (1977).

An evaluation of light-mediated vertical migration of fish based on hydroacoustic analysis of the diel vertical movements of rainbow smelt (Osmerus mordax)

1995 ◽  
Vol 52 (3) ◽  
pp. 504-511 ◽  
Author(s):  
A. R. Appenzeller ◽  
W. C. Leggett
Keyword(s):  
Vertical Migration ◽  
Strong Relationship ◽  
Fish Population ◽  
Osmerus Mordax ◽  
Ambient Light ◽  
Rainbow Smelt ◽  
Vertical Movements ◽  
Light Levels ◽  
Vertical Distributions ◽  
Lower Light

We used hydroacoustics to examine diel changes in the vertical distributions of rainbow smelt, Osmerus mordax, in Lake Memphremagog, Quebec/Vermont. Our objective was to evaluate hypotheses linking diel vertical movements of fish with light levels. Smelt distributions were also monitored from June through October (1988 and 1990) to evaluate seasonal changes in their behavior. A strong relationship (r2 = 0.83) between ambient light intensities and the upper fish layer in the water column was observed. Fish depth was also related to the depth of the thermocline during the night and when surface water temperatures were > 18 °C. The most characteristic feature was the strong avoidance of light levels > 0.1 μW/cm2. However, we found considerable variation in lower light levels experienced by the whole fish population. The results suggest that existing models of anti-predation behavior relating light and fish depth are consistent, with some limitations, with patterns of diel vertical migration in rainbow smelt.

A neural theory of circadian rhythms: Aschoff's rule in diurnal and nocturnal mammals

1984 ◽  
Vol 247 (6) ◽  
pp. R1067-R1082 ◽  
Author(s):  
G. A. Carpenter ◽  
S. Grossberg
Keyword(s):  
Neural Model ◽  
Light Level ◽  
Behavioral Activity ◽  
Circadian Period ◽  
Suprachiasmatic Nuclei ◽  
Light Levels ◽  
Lower Light ◽  
The Stability ◽  
Eye Closure ◽  
Nocturnal Mammals

A neural model of the suprachiasmatic nuclei suggests how behavioral activity, rest, and circadian period depend on light intensity in diurnal and nocturnal mammals. These properties are traced to the action of light input (external zeitgeber) and an activity-mediated fatigue signal (internal zeitgeber) on the circadian pacemaker. Light enhances activity of the diurnal model and suppresses activity of the nocturnal model. Fatigue suppresses activity in both diurnal and nocturnal models. The asymmetrical action of light and fatigue in diurnal vs. nocturnal models explains the more consistent adherence of nocturnal mammals to Aschoff's rule, the consistent adherence of both diurnal and nocturnal mammals to the circadian rule, and the tendency of nocturnal mammals to lose circadian rhythmicity at lower light levels than diurnal mammals. The fatigue signal is related to the sleep process S of Borbely (Hum. Neurobiol. 1: 195–204, 1982.) and contributes to the stability of circadian period. Two predictions follow: diurnal mammals obey Aschoff's rule less consistently during a self-selected light-dark cycle than in constant light, and if light level is increased enough during sleep in diurnal mammals to compensate for eye closure, then Aschoff's rule will hold more consistently. The results are compared with those of Enright's model.

Interspecific variation in the response of growth, crown morphology, and survivorship to light of six tree species in the conifer belt of the Bhutan Himalayas

2004 ◽  
Vol 34 (5) ◽  
pp. 1093-1107 ◽  
Author(s):  
Georg Gratzer ◽  
Andras Darabant ◽  
Purna B Chhetri ◽  
Prem Bahadur Rai ◽  
Otto Eckmüllner
Keyword(s):  
Tree Species ◽  
Radial Growth ◽  
Interspecific Variation ◽  
Low Light ◽  
Continuous Growth ◽  
Light Levels ◽  
Shade Tolerant Species ◽  
Lower Light ◽  
Crown Morphology ◽  
Changing Light

The responses of radial and height growth, plant architecture, and the probability of mortality of saplings to varying light levels were quantified for six tree species in temperate conifer forests of the Bhutan Himalayas. Increases in growth with increasing light were comparable with those of high latitude tree species but lower than those of tropical tree species and temperate species in North America. The shade-tolerant species Tsuga dumosa (D. Don.) Eichler showed the strongest increase in radial growth at low light and reached asymptotic growth early. It had the deepest crowns in low light and a low decrease of leader growth with decreasing light. It represents a continuous growth type, which invests in height rather than lateral growth under low light conditions. Betula utilis D. Don. showed greater increases in radial growth and a higher mortality at low light than the more shade-tolerant Abies densa Griff., in keeping with the trade-off between survivorship and growth at low light. Picea spinulosa Griff, Larix griffithiana Carriére, and Pinus wallichiana A.B. Jackson showed small increases in growth at low light levels. The latter two species showed no capacity to adapt their morphology in response to changing light levels, which resulted in higher probabilities of mortality at lower light levels. Differences in the probability of mortality at different light levels were more pronounced than differences in the light-growth response, underlining the importance of survivorship at low light for successional dynamics.

scholarly journals Identification of SARS-CoV-2 RNA in Healthcare Heating, Ventilation, and Air Conditioning Units

2020 ◽  
Author(s):  
Patrick F. Horve ◽  
Leslie Dietz ◽  
Mark Fretz ◽  
David A. Constant ◽  
Andrew Wilkes ◽  
...  
Keyword(s):  
Air Conditioning ◽  
High Efficiency ◽  
Healthcare Setting ◽  
Hvac Systems ◽  
Mitigation Strategies ◽  
Healthcare Settings ◽  
Viral Particles ◽  
Air Handling Units ◽  
Available Information

AbstractAvailable information on Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) transmission by small particle aerosols continues to evolve rapidly. To assess the potential role of heating, ventilation, and air conditioning (HVAC) systems in airborne viral transmission, this study sought to determine the viral presence, if any, on air handling units in a healthcare setting where Coronavirus Disease 2019 (COVID-19) patients were being treated. The presence of SARS-CoV-2 RNA was detected in approximately 25% of samples taken from nine different locations in multiple air handlers. While samples were not evaluated for viral infectivity, the presence of viral RNA in air handlers raises the possibility that viral particles can enter and travel within the air handling system of a hospital, from room return air through high efficiency MERV-15 filters and into supply air ducts. Although no known transmission events were determined to be associated with these specimens, the findings suggest the potential for HVAC systems to facilitate transmission by environmental contamination via shared air volumes with locations remote from areas where infected persons reside. More work is needed to further evaluate the risk of SARS-CoV-2 transmission via HVAC systems and to verify effectiveness of building operations mitigation strategies for the protection of building occupants. These results are important within and outside of healthcare settings and may present a matter of some urgency for building operators of facilities that are not equipped with high-efficiency filtration.

scholarly journals Critical loads of nitrogen deposition and critical levels of atmospheric ammonia for mediterranean evergreen woodlands

2011 ◽  
Vol 8 (6) ◽  
pp. 11139-11163
Author(s):  
P. Pinho ◽  
M. R. Theobald ◽  
T. Dias ◽  
Y. S. Tang ◽  
C. Cruz ◽  
...  
Keyword(s):  
Functional Groups ◽  
Significant Relationship ◽  
Critical Loads ◽  
High Sensitivity ◽  
N Deposition ◽  
Global Changes ◽  
Critical Levels ◽  
Natural Ecosystems ◽  
Epiphytic Lichen ◽  
Atmospheric Ammonia

Abstract. Nitrogen (N) has emerged in recent years as a key factor associated with global changes, with impacts on biodiversity, ecosystems functioning and human health. In order to ameliorate the effects of excessive N, safety thresholds have been established, such as critical loads (deposition fluxes) and levels (concentrations). For Mediterranean ecosystems, few studies have been carried out to assess these parameters. Our objective was therefore to determine the critical loads of N deposition and long-term critical levels of atmospheric ammonia for Mediterranean evergreen woodlands. For that we have considered changes in epiphytic lichen communities, which have been shown to be one of the most sensitive to excessive N. Based on a classification of lichen species according to their tolerance to N we grouped species into response functional groups, which we used as a tool to determine the critical loads and levels. This was done under Mediterranean climate, in evergreen cork-oak woodlands, by sampling lichen functional diversity and annual atmospheric ammonia concentrations and modelling N deposition downwind from a reduced N source (a cattle barn). By modelling the highly significant relationship between lichen functional groups and N deposition, the critical load was estimated to be below 26 kg (N) ha−1 yr−1, which is within the upper range established for other semi-natural ecosystems. By modelling the highly significant relationship of lichen functional groups with annual atmospheric ammonia concentration, the critical level was estimated to be below 1.9 μg m−3, in agreement with recent studies for other ecosystems. Taking into account the high sensitivity of lichen communities to excessive N, these values should be taken into account in policies that aim at protecting Mediterranean woodlands from the initial effects of excessive N.

scholarly journals High sensitivity and interindividual variability in the response of the human circadian system to evening light

2019 ◽  
pp. 201901824 ◽  
Author(s):  
Andrew J. K. Phillips ◽  
Parisa Vidafar ◽  
Angus C. Burns ◽  
Elise M. McGlashan ◽  
Clare Anderson ◽  
...  
Keyword(s):  
Dose Response ◽  
Interindividual Variability ◽  
High Sensitivity ◽  
Light Level ◽  
Circadian System ◽  
Response Curves ◽  
Individual Level ◽  
Melatonin Suppression ◽  
Light Intensities ◽  
Sensitive Individual

Before the invention of electric lighting, humans were primarily exposed to intense (>300 lux) or dim (<30 lux) environmental light—stimuli at extreme ends of the circadian system’s dose–response curve to light. Today, humans spend hours per day exposed to intermediate light intensities (30–300 lux), particularly in the evening. Interindividual differences in sensitivity to evening light in this intensity range could therefore represent a source of vulnerability to circadian disruption by modern lighting. We characterized individual-level dose–response curves to light-induced melatonin suppression using a within-subjects protocol. Fifty-five participants (aged 18–30) were exposed to a dim control (<1 lux) and a range of experimental light levels (10–2,000 lux for 5 h) in the evening. Melatonin suppression was determined for each light level, and the effective dose for 50% suppression (ED50) was computed at individual and group levels. The group-level fitted ED50 was 24.60 lux, indicating that the circadian system is highly sensitive to evening light at typical indoor levels. Light intensities of 10, 30, and 50 lux resulted in later apparent melatonin onsets by 22, 77, and 109 min, respectively. Individual-level ED50 values ranged by over an order of magnitude (6 lux in the most sensitive individual, 350 lux in the least sensitive individual), with a 26% coefficient of variation. These findings demonstrate that the same evening-light environment is registered by the circadian system very differently between individuals. This interindividual variability may be an important factor for determining the circadian clock’s role in human health and disease.

scholarly journals Biotic and anthropogenic forces rival climatic/abiotic factors in determining global plant population growth and fitness

2019 ◽  
Vol 117 (2) ◽  
pp. 1107-1112 ◽  
Author(s):  
William F. Morris ◽  
Johan Ehrlén ◽  
Johan P. Dahlgren ◽  
Alexander K. Loomis ◽  
Allison M. Louthan
Keyword(s):  
Population Growth ◽  
Environmental Changes ◽  
Abiotic Factors ◽  
Natural Populations ◽  
Natural Disturbance ◽  
Mitigation Strategies ◽  
Terrestrial Plants ◽  
Evolutionary Trajectories ◽  
Available Information ◽  
Anthropogenic Drivers

Multiple, simultaneous environmental changes, in climatic/abiotic factors, interacting species, and direct human influences, are impacting natural populations and thus biodiversity, ecosystem services, and evolutionary trajectories. Determining whether the magnitudes of the population impacts of abiotic, biotic, and anthropogenic drivers differ, accounting for their direct effects and effects mediated through other drivers, would allow us to better predict population fates and design mitigation strategies. We compiled 644 paired values of the population growth rate (λ) from high and low levels of an identified driver from demographic studies of terrestrial plants. Among abiotic drivers, natural disturbance (not climate), and among biotic drivers, interactions with neighboring plants had the strongest effects on λ. However, when drivers were combined into the 3 main types, their average effects on λ did not differ. For the subset of studies that measured both the average and variability of the driver, λ was marginally more sensitive to 1 SD of change in abiotic drivers relative to biotic drivers, but sensitivity to biotic drivers was still substantial. Similar impact magnitudes for abiotic/biotic/anthropogenic drivers hold for plants of different growth forms, for different latitudinal zones, and for biomes characterized by harsher or milder abiotic conditions, suggesting that all 3 drivers have equivalent impacts across a variety of contexts. Thus, the best available information about the integrated effects of drivers on all demographic rates provides no justification for ignoring drivers of any of these 3 types when projecting ecological and evolutionary responses of populations and of biodiversity to environmental changes.

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