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Mammalian ranges are experiencing erosion of natural darkness.

Duffy JP, Bennie J, Durán AP, Gaston KJ - Sci Rep (2015)

Bottom Line: The continuous increase in the intensity and extent of anthropogenic artificial light has significantly shaped Earth's nighttime environment.This environmental change has effects across the natural world, with consequences for organismal physiology and behaviour and the abundances and distributions of species.Over time (1992-2012), an increase in mean light intensity was found for the ranges of the majority of species, with very few experiencing a decrease.

View Article: PubMed Central - PubMed

Affiliation: Environment and Sustainability Institute, University of Exeter, Penryn, Cornwall TR10 9FE, UK.

ABSTRACT
The continuous increase in the intensity and extent of anthropogenic artificial light has significantly shaped Earth's nighttime environment. This environmental change has effects across the natural world, with consequences for organismal physiology and behaviour and the abundances and distributions of species. Here, we evaluate for the first time the relations between the spatio-temporal patterns of anthropogenic nighttime light and the distribution of terrestrial mammals, one of the most endangered species groups and one that expresses varying time partitioning strategies. Using descriptive statistics, trend tests and spatial prioritization analysis we show that in most places on earth there is a terrestrial mammal species whose range is experiencing detectable artificial light. For most species this tends only to be for small parts of their range, and those affected across large parts are typically rare. Over time (1992-2012), an increase in mean light intensity was found for the ranges of the majority of species, with very few experiencing a decrease. Moreover, nocturnal species are more likely to experience an increase in light within their ranges. This is of conservation concern as many terrestrial mammals are nocturnal and therefore often particularly vulnerable to a pressure such as artificial light at night.

No MeSH data available.


The magnitude and trend of conflict between ALAN and mammals.(a) The difference in the spread of light between the first and last four years for all species, (b) A comparison of the average intensity of light between the first and last four years for affected species (those that have a mean DN higher than 0), (c) The strength of trend in ALAN over the 21 year study period by tau value (Mann-Kendall trend test). Grey shaded areas indicate significantly negative and positive results (p < 0.05) respectively, for affected species.
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f2: The magnitude and trend of conflict between ALAN and mammals.(a) The difference in the spread of light between the first and last four years for all species, (b) A comparison of the average intensity of light between the first and last four years for affected species (those that have a mean DN higher than 0), (c) The strength of trend in ALAN over the 21 year study period by tau value (Mann-Kendall trend test). Grey shaded areas indicate significantly negative and positive results (p < 0.05) respectively, for affected species.

Mentions: In very few places was there a terrestrial mammal species whose geographic range was not experiencing some detectable ALAN (Fig. 1(c)). Examples of these areas include small pockets of land found in Madagascar, central Australia, Baja California in Mexico, the Amazon rainforest, parts of large islands and several small islands in south-east Asia. For many species lighting occurred in only a small proportion of their range, with 3594 experiencing ALAN in less than 10% of their range during 1992–1995 (Fig. 2a). As the proportion of the geographic range experiencing light increased, the geographical focus shifted mainly to the Northern Hemisphere, specifically, N. America, Europe, and Japan (Fig. 1(d–e)). Few species were experiencing ALAN in more than 60% of their range, with those with ranges bound to small islands predominantly falling into this group (Fig. 1f). Indeed, those species experiencing ALAN over high proportions of their geographic ranges were typically rare (small range sizes), with the more widely distributed species almost invariably occurring in many places with no ALAN (Fig. 2b).


Mammalian ranges are experiencing erosion of natural darkness.

Duffy JP, Bennie J, Durán AP, Gaston KJ - Sci Rep (2015)

The magnitude and trend of conflict between ALAN and mammals.(a) The difference in the spread of light between the first and last four years for all species, (b) A comparison of the average intensity of light between the first and last four years for affected species (those that have a mean DN higher than 0), (c) The strength of trend in ALAN over the 21 year study period by tau value (Mann-Kendall trend test). Grey shaded areas indicate significantly negative and positive results (p < 0.05) respectively, for affected species.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4496780&req=5

f2: The magnitude and trend of conflict between ALAN and mammals.(a) The difference in the spread of light between the first and last four years for all species, (b) A comparison of the average intensity of light between the first and last four years for affected species (those that have a mean DN higher than 0), (c) The strength of trend in ALAN over the 21 year study period by tau value (Mann-Kendall trend test). Grey shaded areas indicate significantly negative and positive results (p < 0.05) respectively, for affected species.
Mentions: In very few places was there a terrestrial mammal species whose geographic range was not experiencing some detectable ALAN (Fig. 1(c)). Examples of these areas include small pockets of land found in Madagascar, central Australia, Baja California in Mexico, the Amazon rainforest, parts of large islands and several small islands in south-east Asia. For many species lighting occurred in only a small proportion of their range, with 3594 experiencing ALAN in less than 10% of their range during 1992–1995 (Fig. 2a). As the proportion of the geographic range experiencing light increased, the geographical focus shifted mainly to the Northern Hemisphere, specifically, N. America, Europe, and Japan (Fig. 1(d–e)). Few species were experiencing ALAN in more than 60% of their range, with those with ranges bound to small islands predominantly falling into this group (Fig. 1f). Indeed, those species experiencing ALAN over high proportions of their geographic ranges were typically rare (small range sizes), with the more widely distributed species almost invariably occurring in many places with no ALAN (Fig. 2b).

Bottom Line: The continuous increase in the intensity and extent of anthropogenic artificial light has significantly shaped Earth's nighttime environment.This environmental change has effects across the natural world, with consequences for organismal physiology and behaviour and the abundances and distributions of species.Over time (1992-2012), an increase in mean light intensity was found for the ranges of the majority of species, with very few experiencing a decrease.

View Article: PubMed Central - PubMed

Affiliation: Environment and Sustainability Institute, University of Exeter, Penryn, Cornwall TR10 9FE, UK.

ABSTRACT
The continuous increase in the intensity and extent of anthropogenic artificial light has significantly shaped Earth's nighttime environment. This environmental change has effects across the natural world, with consequences for organismal physiology and behaviour and the abundances and distributions of species. Here, we evaluate for the first time the relations between the spatio-temporal patterns of anthropogenic nighttime light and the distribution of terrestrial mammals, one of the most endangered species groups and one that expresses varying time partitioning strategies. Using descriptive statistics, trend tests and spatial prioritization analysis we show that in most places on earth there is a terrestrial mammal species whose range is experiencing detectable artificial light. For most species this tends only to be for small parts of their range, and those affected across large parts are typically rare. Over time (1992-2012), an increase in mean light intensity was found for the ranges of the majority of species, with very few experiencing a decrease. Moreover, nocturnal species are more likely to experience an increase in light within their ranges. This is of conservation concern as many terrestrial mammals are nocturnal and therefore often particularly vulnerable to a pressure such as artificial light at night.

No MeSH data available.