The Experts below are selected from a list of 183 Experts worldwide ranked by ideXlab platform
Gyorgy Kriska - One of the best experts on this subject based on the ideXlab platform.
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lamp lit bridges as dual light traps for the night swarming mayfly Ephoron virgo interaction of polarized and unpolarized light pollution
PLOS ONE, 2015Co-Authors: Denes Szaz, Gabor Horvath, Andras Barta, Bruce A Robertson, Alexandra Farkas, Adam Egri, Nikolett Tarjanyi, Gergely Racz, Gyorgy KriskaAbstract:Ecological photopollution created by artificial night lighting can alter animal behavior and lead to population declines and biodiversity loss. Polarized light pollution is a second type of photopollution that triggers water-seeking insects to ovisposit on smooth and dark man-made objects, because they simulate the polarization signatures of natural water bodies. We document a case study of the interaction of these two forms of photopollution by conducting observations and experiments near a lamp-lit bridge over the river Danube that attracts mass swarms of the mayfly Ephoron virgo away from the river to oviposit on the asphalt road of the bridge. Millions of mayflies swarmed near bridge-lights for two weeks. We found these swarms to be composed of 99% adult females performing their upstream compensatory flight and were attracted upward toward unpolarized bridge-lamp light, and away from the horizontally polarized light trail of the river. Imaging polarimetry confirmed that the asphalt surface of the bridge was strongly and horizontally polarized, providing a supernormal ovipositional cue to Ephoron virgo, while other parts of the bridge were poor polarizers of lamplight. Collectively, we confirm that Ephoron virgo is independently attracted to both unpolarized and polarized light sources, that both types of photopollution are being produced at the bridge, and that spatial patterns of swarming and oviposition are consistent with evolved behaviors being triggered maladaptively by these two types of light pollution. We suggest solutions to bridge and lighting design that should prevent or mitigate the impacts of such scenarios in the future. The detrimental impacts of such scenarios may extend beyond Ephoron virgo.
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Estimated numbers of Ephoron virgo mayflies attracted to polarized and unpolarized light sources placed above the Danube river on four dates in 2012.
2015Co-Authors: Denes Szaz, Gabor Horvath, Andras Barta, Bruce A Robertson, Alexandra Farkas, Adam Egri, Nikolett Tarjanyi, Gergely Racz, Gyorgy KriskaAbstract:Number (mean ± standard deviation) of mayflies attracted to horizontally polarized (continuous line) and unpolarized (dashed line) light as a function of time (= local summer time = GMT + 2 hours, where GMT = Greenwich Mean Time). Each estimate is based on 10 photographs (see subsection Experiments with linear polarizers of the Materials and Methods). Comparisons of total detections over the course of each test indicate that more individuals were attracted to polarized versus unpolarized light sources of the same intensity: (A) 23 August, N = 11582, U = 181, Z = 10.302, p < 0.00001; (B) 24 August, N = 22786, U = 674.5, Z = 11.388, p < 0.00001; (C) 27 August, N = 5425, U = 303.5, Z = 8.945, p < 0.00001; (D) 28 August, N = 93935, U = 8682, Z = 10.465, p < 0.00001, where N is the number of total mayfly detections, U is the parameter giving the sum of ranks used in the non-parametric method, Z is the standard deviation of data for a given p, and p is the level of significancy (p < 0.05 means significant).
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Nocturnal artificial sources of unpolarized and horizontally polarized light interact to attract polarotactic insects.
2015Co-Authors: Denes Szaz, Gabor Horvath, Andras Barta, Bruce A Robertson, Alexandra Farkas, Adam Egri, Nikolett Tarjanyi, Gergely Racz, Gyorgy KriskaAbstract:Unpolarlized light sources (e.g., street-lamps) may attract perching or flying nocturnal polarotactic insects directly (Ephoron virgo mayfly illustrated). Alternatively, unpolarized light from the street-lamp can become horizontally polarized through reflection from smooth, dark surfaces like asphalt, simulating the appearance of a water body.
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(A, B) Color photograph, patterns of the degree d and angle α (clockwise from the vertical) of linear polarization, and areas detected polarotactically as water (for which d > 15% and 80° < α < 100°) of the dry asphalt road on the bridge (above the river Danube at Tahitótfalu) illuminated by bridge-lamps at night during the mass congregation of Ephoron virgo mayflies.
2015Co-Authors: Denes Szaz, Gabor Horvath, Andras Barta, Bruce A Robertson, Alexandra Farkas, Adam Egri, Nikolett Tarjanyi, Gergely Racz, Gyorgy KriskaAbstract:The patterns were measured by imaging polarimetry in the blue (450 nm) part of the spectrum from two different directions of view, when the optical axis of the polarimeter pointed toward North (A) and West (B). The angle of elevation of the optical axis of the polarimeter was 20° from the horizontal. In the α-pattern the local direction of polarization of asphalt-reflected light is shown by a double-headed arrow. The white spot composed of millions of Ephoron virgo carcasses on the asphalt road below the bridge-lamp is well visible on the photographs as well as in the patterns of the degree of polarization d and the area detected as water.
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Lamp-Lit Bridges as Dual Light-Traps for the Night-Swarming Mayfly, Ephoron virgo: Interaction of Polarized and Unpolarized Light Pollution - Fig 2
2015Co-Authors: Denes Szaz, Gabor Horvath, Andras Barta, Bruce A Robertson, Alexandra Farkas, Adam Egri, Nikolett Tarjanyi, Gergely Racz, Gyorgy KriskaAbstract:(A) Mass swarming of Ephoron virgo mayflies at night in Tahitótfalu (northern Hungary) at a bridge overarching the river Danube. (B) During the swarming we could observe that female mayflies performing their compensatory flight, flew up to the bridge-lamps. One part of females reaching the bridge landed on the asphalt road to oviposit, whereas the others joined to the swarm of several thousands individuals around the bridge-lamps. (C) With the progress of mass congregation the ovipositing females covered in greater and greater deal the asphalt road of the bridge. The mass of mayflies containing already perished and still ovipositing individuals formed large, extended, white stains. (D) The yellow egg batches are easy to recognise in the white crowd of mayflies, that consisted of several thousand eggs each.
Koji Tojo - One of the best experts on this subject based on the ideXlab platform.
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phylogeography of the east asian polymitarcyid mayfly genus Ephoron ephemeroptera polymitarcyidae a comparative analysis of molecular and ecological characteristics
Biological Journal of The Linnean Society, 2013Co-Authors: Kazuki Sekiné, Fumio Hayashi, Koji TojoAbstract:In East Asia, the mayfly genus Ephoron, a member of Polymitarcyidae, has been classified into three species: Ephoron eophilum, Ephoron limnobium, and Ephoron shigae. Using the nuclear histone 3 and internal transcribed spacer 1 and mitochondrial 16S rRNA and cytochrome c oxidase subunit I genes, we investigated the phylogenetic relationships of these mayflies. Ephoron limnobium formed polyphyletic relationships within the clade of Japanese E. shigae and shared identical sequences with E. shigae, suggesting that E. limnobium is a synonym of E. shigae. Monophyly was supported in E. eophilum, Korean E. shigae, and E. limnobium + Japanese E. shigae. Ephoron eophilum that co-occurs with the other Ephoron species has several peculiar traits in its adult swarming period and karyotype. This suggests that both pre- and post-zygotic isolation are likely to have promoted speciation of these Ephoron species. The divergence between E. eophilum and E. shigae would have occurred from the late Late Miocene to Early Pliocene according to the Bayesian relaxed clock model calibrated using the mitochondrial substitution rate. The area currently inhabited by E. eophilum emerged above sea level some 0.1 Mya, suggesting that E. eophilum moved into this area from other areas that it occupied prior to this time. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109, 181–202.
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potential for parthenogenesis of virgin females in a bisexual population of the geographically parthenogenetic mayfly Ephoron shigae insecta ephemeroptera polymitarcyidae
Biological Journal of The Linnean Society, 2009Co-Authors: Kazuki Sekiné, Koji TojoAbstract:The burrowing polymitarcyid mayfly Ephoron shigae is a geographically parthenogenetic species. Interestingly, the distributions of the bisexual and unisexual populations overlap broadly in their respective geographic ranges. In this mayfly, obligatory diploid thelytoky appears within unisexual populations. In the present study, we examined the potential for parthenogenesis or the parthenogenetic ability of females in a bisexual population aiming to understand the emergence of unisexual populations. The results obtained revealed that females in the examined bisexual populations showed a potential for diploid thelytoky as also seen in the unisexual populations, although, in females from bisexual populations, the development success rates of their unfertilized eggs were considerably lower than those of virgin females from unisexual populations. In the three bisexual reproducing species (Ephemera japonica, Ephemera strigata, and Ephemera orientalis) in the closely-related family Ephemeridae, diploid thelytoky (i.e. tychoparthenogenesis; < 3%) was also observed. However, in this case, the parthenogenetic development success rates of unfertilized eggs were significantly lower than those of virgin females in the bisexual (Hino-yosui Irrigation Canal) population of E. shigae. Accordingly, we suggest that parthenogenetic ability (i.e. tychoparthenogenesis or facultative parthenogenesis) in bisexual populations of E. shigae may facilitate the evolutionary transition to unisexual populations with fully obligatory parthenogenesis. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99, 326–334.
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Reproductive mode of the geographic parthenogenetic mayfly Ephoron shigae, with findings from some new localities (Insecta: Ephemeroptera, Polymitarcyidae)
Limnology, 2006Co-Authors: Koji Tojo, Kazuki Sekiné, Atsushi MatsumotoAbstract:The burrowing polymitarcyid mayfly Ephoron shigae is distributed widely in Japan. Some populations are bisexual, others are unisexual, and the distributions of the two types overlap broadly. Experimental evidence of parthenogenetic reproduction, long suspected in unisexual populations, is presented here, based on a comparative analysis of the developmental rate of fertilized and unfertilized eggs. The developmental rate of fertilized eggs from 20 mated females in a bisexual population was 98.4% ± 0.73% (mean ± SD), and no unfertilized eggs from 20 virgin females in that population developed. The developmental rates of unfertilized eggs in two unisexual populations were 89.0% ± 4.59% and 84.2% ± 1.96%, respectively. This article presents experimental evidence of geographic parthenogenesis in E. shigae and provides support for the previous interpretation. In addition, we discuss the relationship between the sex ratio of each population and the developmental rate of fertilized versus unfertilized eggs from the females in those populations.
Denes Szaz - One of the best experts on this subject based on the ideXlab platform.
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Interaction of Polarized and Unpolarized Light Pollution
2016Co-Authors: Night-swarming Mayfly, Denes Szaz, Gabor Horvath, Andras Barta, Bruce A Robertson, Adam Egri, Nikolett Tarjanyi, Ephoron Virgo, Ra Farkas, Gergely RaczAbstract:Ecological photopollution created by artificial night lighting can alter animal behavior and lead to population declines and biodiversity loss. Polarized light pollution is a second type of photopollution that triggers water-seeking insects to ovisposit on smooth and dark man-made objects, because they simulate the polarization signatures of natural water bodies. We document a case study of the interaction of these two forms of photopollution by con-ducting observations and experiments near a lamp-lit bridge over the river Danube that at-tracts mass swarms of the mayfly Ephoron virgo away from the river to oviposit on the asphalt road of the bridge. Millions of mayflies swarmed near bridge-lights for two weeks. We found these swarms to be composed of 99 % adult females performing their upstream compensatory flight and were attracted upward toward unpolarized bridge-lamp light, and away from the horizontally polarized light trail of the river. Imaging polarimetry confirmed that the asphalt surface of the bridge was strongly and horizontally polarized, providing a su-pernormal ovipositional cue to Ephoron virgo, while other parts of the bridge were poor polarizers of lamplight. Collectively, we confirm that Ephoron virgo is independently at
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lamp lit bridges as dual light traps for the night swarming mayfly Ephoron virgo interaction of polarized and unpolarized light pollution
PLOS ONE, 2015Co-Authors: Denes Szaz, Gabor Horvath, Andras Barta, Bruce A Robertson, Alexandra Farkas, Adam Egri, Nikolett Tarjanyi, Gergely Racz, Gyorgy KriskaAbstract:Ecological photopollution created by artificial night lighting can alter animal behavior and lead to population declines and biodiversity loss. Polarized light pollution is a second type of photopollution that triggers water-seeking insects to ovisposit on smooth and dark man-made objects, because they simulate the polarization signatures of natural water bodies. We document a case study of the interaction of these two forms of photopollution by conducting observations and experiments near a lamp-lit bridge over the river Danube that attracts mass swarms of the mayfly Ephoron virgo away from the river to oviposit on the asphalt road of the bridge. Millions of mayflies swarmed near bridge-lights for two weeks. We found these swarms to be composed of 99% adult females performing their upstream compensatory flight and were attracted upward toward unpolarized bridge-lamp light, and away from the horizontally polarized light trail of the river. Imaging polarimetry confirmed that the asphalt surface of the bridge was strongly and horizontally polarized, providing a supernormal ovipositional cue to Ephoron virgo, while other parts of the bridge were poor polarizers of lamplight. Collectively, we confirm that Ephoron virgo is independently attracted to both unpolarized and polarized light sources, that both types of photopollution are being produced at the bridge, and that spatial patterns of swarming and oviposition are consistent with evolved behaviors being triggered maladaptively by these two types of light pollution. We suggest solutions to bridge and lighting design that should prevent or mitigate the impacts of such scenarios in the future. The detrimental impacts of such scenarios may extend beyond Ephoron virgo.
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Estimated numbers of Ephoron virgo mayflies attracted to polarized and unpolarized light sources placed above the Danube river on four dates in 2012.
2015Co-Authors: Denes Szaz, Gabor Horvath, Andras Barta, Bruce A Robertson, Alexandra Farkas, Adam Egri, Nikolett Tarjanyi, Gergely Racz, Gyorgy KriskaAbstract:Number (mean ± standard deviation) of mayflies attracted to horizontally polarized (continuous line) and unpolarized (dashed line) light as a function of time (= local summer time = GMT + 2 hours, where GMT = Greenwich Mean Time). Each estimate is based on 10 photographs (see subsection Experiments with linear polarizers of the Materials and Methods). Comparisons of total detections over the course of each test indicate that more individuals were attracted to polarized versus unpolarized light sources of the same intensity: (A) 23 August, N = 11582, U = 181, Z = 10.302, p < 0.00001; (B) 24 August, N = 22786, U = 674.5, Z = 11.388, p < 0.00001; (C) 27 August, N = 5425, U = 303.5, Z = 8.945, p < 0.00001; (D) 28 August, N = 93935, U = 8682, Z = 10.465, p < 0.00001, where N is the number of total mayfly detections, U is the parameter giving the sum of ranks used in the non-parametric method, Z is the standard deviation of data for a given p, and p is the level of significancy (p < 0.05 means significant).
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Nocturnal artificial sources of unpolarized and horizontally polarized light interact to attract polarotactic insects.
2015Co-Authors: Denes Szaz, Gabor Horvath, Andras Barta, Bruce A Robertson, Alexandra Farkas, Adam Egri, Nikolett Tarjanyi, Gergely Racz, Gyorgy KriskaAbstract:Unpolarlized light sources (e.g., street-lamps) may attract perching or flying nocturnal polarotactic insects directly (Ephoron virgo mayfly illustrated). Alternatively, unpolarized light from the street-lamp can become horizontally polarized through reflection from smooth, dark surfaces like asphalt, simulating the appearance of a water body.
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(A, B) Color photograph, patterns of the degree d and angle α (clockwise from the vertical) of linear polarization, and areas detected polarotactically as water (for which d > 15% and 80° < α < 100°) of the dry asphalt road on the bridge (above the river Danube at Tahitótfalu) illuminated by bridge-lamps at night during the mass congregation of Ephoron virgo mayflies.
2015Co-Authors: Denes Szaz, Gabor Horvath, Andras Barta, Bruce A Robertson, Alexandra Farkas, Adam Egri, Nikolett Tarjanyi, Gergely Racz, Gyorgy KriskaAbstract:The patterns were measured by imaging polarimetry in the blue (450 nm) part of the spectrum from two different directions of view, when the optical axis of the polarimeter pointed toward North (A) and West (B). The angle of elevation of the optical axis of the polarimeter was 20° from the horizontal. In the α-pattern the local direction of polarization of asphalt-reflected light is shown by a double-headed arrow. The white spot composed of millions of Ephoron virgo carcasses on the asphalt road below the bridge-lamp is well visible on the photographs as well as in the patterns of the degree of polarization d and the area detected as water.
Gabor Horvath - One of the best experts on this subject based on the ideXlab platform.
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Interaction of Polarized and Unpolarized Light Pollution
2016Co-Authors: Night-swarming Mayfly, Denes Szaz, Gabor Horvath, Andras Barta, Bruce A Robertson, Adam Egri, Nikolett Tarjanyi, Ephoron Virgo, Ra Farkas, Gergely RaczAbstract:Ecological photopollution created by artificial night lighting can alter animal behavior and lead to population declines and biodiversity loss. Polarized light pollution is a second type of photopollution that triggers water-seeking insects to ovisposit on smooth and dark man-made objects, because they simulate the polarization signatures of natural water bodies. We document a case study of the interaction of these two forms of photopollution by con-ducting observations and experiments near a lamp-lit bridge over the river Danube that at-tracts mass swarms of the mayfly Ephoron virgo away from the river to oviposit on the asphalt road of the bridge. Millions of mayflies swarmed near bridge-lights for two weeks. We found these swarms to be composed of 99 % adult females performing their upstream compensatory flight and were attracted upward toward unpolarized bridge-lamp light, and away from the horizontally polarized light trail of the river. Imaging polarimetry confirmed that the asphalt surface of the bridge was strongly and horizontally polarized, providing a su-pernormal ovipositional cue to Ephoron virgo, while other parts of the bridge were poor polarizers of lamplight. Collectively, we confirm that Ephoron virgo is independently at
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lamp lit bridges as dual light traps for the night swarming mayfly Ephoron virgo interaction of polarized and unpolarized light pollution
PLOS ONE, 2015Co-Authors: Denes Szaz, Gabor Horvath, Andras Barta, Bruce A Robertson, Alexandra Farkas, Adam Egri, Nikolett Tarjanyi, Gergely Racz, Gyorgy KriskaAbstract:Ecological photopollution created by artificial night lighting can alter animal behavior and lead to population declines and biodiversity loss. Polarized light pollution is a second type of photopollution that triggers water-seeking insects to ovisposit on smooth and dark man-made objects, because they simulate the polarization signatures of natural water bodies. We document a case study of the interaction of these two forms of photopollution by conducting observations and experiments near a lamp-lit bridge over the river Danube that attracts mass swarms of the mayfly Ephoron virgo away from the river to oviposit on the asphalt road of the bridge. Millions of mayflies swarmed near bridge-lights for two weeks. We found these swarms to be composed of 99% adult females performing their upstream compensatory flight and were attracted upward toward unpolarized bridge-lamp light, and away from the horizontally polarized light trail of the river. Imaging polarimetry confirmed that the asphalt surface of the bridge was strongly and horizontally polarized, providing a supernormal ovipositional cue to Ephoron virgo, while other parts of the bridge were poor polarizers of lamplight. Collectively, we confirm that Ephoron virgo is independently attracted to both unpolarized and polarized light sources, that both types of photopollution are being produced at the bridge, and that spatial patterns of swarming and oviposition are consistent with evolved behaviors being triggered maladaptively by these two types of light pollution. We suggest solutions to bridge and lighting design that should prevent or mitigate the impacts of such scenarios in the future. The detrimental impacts of such scenarios may extend beyond Ephoron virgo.
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Estimated numbers of Ephoron virgo mayflies attracted to polarized and unpolarized light sources placed above the Danube river on four dates in 2012.
2015Co-Authors: Denes Szaz, Gabor Horvath, Andras Barta, Bruce A Robertson, Alexandra Farkas, Adam Egri, Nikolett Tarjanyi, Gergely Racz, Gyorgy KriskaAbstract:Number (mean ± standard deviation) of mayflies attracted to horizontally polarized (continuous line) and unpolarized (dashed line) light as a function of time (= local summer time = GMT + 2 hours, where GMT = Greenwich Mean Time). Each estimate is based on 10 photographs (see subsection Experiments with linear polarizers of the Materials and Methods). Comparisons of total detections over the course of each test indicate that more individuals were attracted to polarized versus unpolarized light sources of the same intensity: (A) 23 August, N = 11582, U = 181, Z = 10.302, p < 0.00001; (B) 24 August, N = 22786, U = 674.5, Z = 11.388, p < 0.00001; (C) 27 August, N = 5425, U = 303.5, Z = 8.945, p < 0.00001; (D) 28 August, N = 93935, U = 8682, Z = 10.465, p < 0.00001, where N is the number of total mayfly detections, U is the parameter giving the sum of ranks used in the non-parametric method, Z is the standard deviation of data for a given p, and p is the level of significancy (p < 0.05 means significant).
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Nocturnal artificial sources of unpolarized and horizontally polarized light interact to attract polarotactic insects.
2015Co-Authors: Denes Szaz, Gabor Horvath, Andras Barta, Bruce A Robertson, Alexandra Farkas, Adam Egri, Nikolett Tarjanyi, Gergely Racz, Gyorgy KriskaAbstract:Unpolarlized light sources (e.g., street-lamps) may attract perching or flying nocturnal polarotactic insects directly (Ephoron virgo mayfly illustrated). Alternatively, unpolarized light from the street-lamp can become horizontally polarized through reflection from smooth, dark surfaces like asphalt, simulating the appearance of a water body.
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(A, B) Color photograph, patterns of the degree d and angle α (clockwise from the vertical) of linear polarization, and areas detected polarotactically as water (for which d > 15% and 80° < α < 100°) of the dry asphalt road on the bridge (above the river Danube at Tahitótfalu) illuminated by bridge-lamps at night during the mass congregation of Ephoron virgo mayflies.
2015Co-Authors: Denes Szaz, Gabor Horvath, Andras Barta, Bruce A Robertson, Alexandra Farkas, Adam Egri, Nikolett Tarjanyi, Gergely Racz, Gyorgy KriskaAbstract:The patterns were measured by imaging polarimetry in the blue (450 nm) part of the spectrum from two different directions of view, when the optical axis of the polarimeter pointed toward North (A) and West (B). The angle of elevation of the optical axis of the polarimeter was 20° from the horizontal. In the α-pattern the local direction of polarization of asphalt-reflected light is shown by a double-headed arrow. The white spot composed of millions of Ephoron virgo carcasses on the asphalt road below the bridge-lamp is well visible on the photographs as well as in the patterns of the degree of polarization d and the area detected as water.
Gergely Racz - One of the best experts on this subject based on the ideXlab platform.
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Interaction of Polarized and Unpolarized Light Pollution
2016Co-Authors: Night-swarming Mayfly, Denes Szaz, Gabor Horvath, Andras Barta, Bruce A Robertson, Adam Egri, Nikolett Tarjanyi, Ephoron Virgo, Ra Farkas, Gergely RaczAbstract:Ecological photopollution created by artificial night lighting can alter animal behavior and lead to population declines and biodiversity loss. Polarized light pollution is a second type of photopollution that triggers water-seeking insects to ovisposit on smooth and dark man-made objects, because they simulate the polarization signatures of natural water bodies. We document a case study of the interaction of these two forms of photopollution by con-ducting observations and experiments near a lamp-lit bridge over the river Danube that at-tracts mass swarms of the mayfly Ephoron virgo away from the river to oviposit on the asphalt road of the bridge. Millions of mayflies swarmed near bridge-lights for two weeks. We found these swarms to be composed of 99 % adult females performing their upstream compensatory flight and were attracted upward toward unpolarized bridge-lamp light, and away from the horizontally polarized light trail of the river. Imaging polarimetry confirmed that the asphalt surface of the bridge was strongly and horizontally polarized, providing a su-pernormal ovipositional cue to Ephoron virgo, while other parts of the bridge were poor polarizers of lamplight. Collectively, we confirm that Ephoron virgo is independently at
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lamp lit bridges as dual light traps for the night swarming mayfly Ephoron virgo interaction of polarized and unpolarized light pollution
PLOS ONE, 2015Co-Authors: Denes Szaz, Gabor Horvath, Andras Barta, Bruce A Robertson, Alexandra Farkas, Adam Egri, Nikolett Tarjanyi, Gergely Racz, Gyorgy KriskaAbstract:Ecological photopollution created by artificial night lighting can alter animal behavior and lead to population declines and biodiversity loss. Polarized light pollution is a second type of photopollution that triggers water-seeking insects to ovisposit on smooth and dark man-made objects, because they simulate the polarization signatures of natural water bodies. We document a case study of the interaction of these two forms of photopollution by conducting observations and experiments near a lamp-lit bridge over the river Danube that attracts mass swarms of the mayfly Ephoron virgo away from the river to oviposit on the asphalt road of the bridge. Millions of mayflies swarmed near bridge-lights for two weeks. We found these swarms to be composed of 99% adult females performing their upstream compensatory flight and were attracted upward toward unpolarized bridge-lamp light, and away from the horizontally polarized light trail of the river. Imaging polarimetry confirmed that the asphalt surface of the bridge was strongly and horizontally polarized, providing a supernormal ovipositional cue to Ephoron virgo, while other parts of the bridge were poor polarizers of lamplight. Collectively, we confirm that Ephoron virgo is independently attracted to both unpolarized and polarized light sources, that both types of photopollution are being produced at the bridge, and that spatial patterns of swarming and oviposition are consistent with evolved behaviors being triggered maladaptively by these two types of light pollution. We suggest solutions to bridge and lighting design that should prevent or mitigate the impacts of such scenarios in the future. The detrimental impacts of such scenarios may extend beyond Ephoron virgo.
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Estimated numbers of Ephoron virgo mayflies attracted to polarized and unpolarized light sources placed above the Danube river on four dates in 2012.
2015Co-Authors: Denes Szaz, Gabor Horvath, Andras Barta, Bruce A Robertson, Alexandra Farkas, Adam Egri, Nikolett Tarjanyi, Gergely Racz, Gyorgy KriskaAbstract:Number (mean ± standard deviation) of mayflies attracted to horizontally polarized (continuous line) and unpolarized (dashed line) light as a function of time (= local summer time = GMT + 2 hours, where GMT = Greenwich Mean Time). Each estimate is based on 10 photographs (see subsection Experiments with linear polarizers of the Materials and Methods). Comparisons of total detections over the course of each test indicate that more individuals were attracted to polarized versus unpolarized light sources of the same intensity: (A) 23 August, N = 11582, U = 181, Z = 10.302, p < 0.00001; (B) 24 August, N = 22786, U = 674.5, Z = 11.388, p < 0.00001; (C) 27 August, N = 5425, U = 303.5, Z = 8.945, p < 0.00001; (D) 28 August, N = 93935, U = 8682, Z = 10.465, p < 0.00001, where N is the number of total mayfly detections, U is the parameter giving the sum of ranks used in the non-parametric method, Z is the standard deviation of data for a given p, and p is the level of significancy (p < 0.05 means significant).
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Nocturnal artificial sources of unpolarized and horizontally polarized light interact to attract polarotactic insects.
2015Co-Authors: Denes Szaz, Gabor Horvath, Andras Barta, Bruce A Robertson, Alexandra Farkas, Adam Egri, Nikolett Tarjanyi, Gergely Racz, Gyorgy KriskaAbstract:Unpolarlized light sources (e.g., street-lamps) may attract perching or flying nocturnal polarotactic insects directly (Ephoron virgo mayfly illustrated). Alternatively, unpolarized light from the street-lamp can become horizontally polarized through reflection from smooth, dark surfaces like asphalt, simulating the appearance of a water body.
-
(A, B) Color photograph, patterns of the degree d and angle α (clockwise from the vertical) of linear polarization, and areas detected polarotactically as water (for which d > 15% and 80° < α < 100°) of the dry asphalt road on the bridge (above the river Danube at Tahitótfalu) illuminated by bridge-lamps at night during the mass congregation of Ephoron virgo mayflies.
2015Co-Authors: Denes Szaz, Gabor Horvath, Andras Barta, Bruce A Robertson, Alexandra Farkas, Adam Egri, Nikolett Tarjanyi, Gergely Racz, Gyorgy KriskaAbstract:The patterns were measured by imaging polarimetry in the blue (450 nm) part of the spectrum from two different directions of view, when the optical axis of the polarimeter pointed toward North (A) and West (B). The angle of elevation of the optical axis of the polarimeter was 20° from the horizontal. In the α-pattern the local direction of polarization of asphalt-reflected light is shown by a double-headed arrow. The white spot composed of millions of Ephoron virgo carcasses on the asphalt road below the bridge-lamp is well visible on the photographs as well as in the patterns of the degree of polarization d and the area detected as water.