Light Pollution endangering the Environment

This is a C&P from Treehugger, a site Slate was sponsoring about a decade or so ago. Interesting place which writes various articles on tiny homes, environment, etc.

The article is about light pollution and how it impacts the environment. When I was the VP for the Township Planning Commission, we had passed an ordinance which regulated light pollution. We were intent on keeping lighting on site rather than allowing it to spray the area with excessive light using shielded parking lot, building, and positioned lighting to minimize light pollution. We were a rural community on the way to becoming suburban. (Been called a lot of things on that board.)

I find this to be an interesting topic the same as I might about find blowing grass clippings into the road, which washes into the road drains, going into the wetlands near the subdivision.

Insects are important to our environment also. They Insects are components of the planet’s ecosystems performing important functions. Insects aerate the soil, pollinate blossoms, control other insect and plant pests. As decomposers, insects help create nutrient rich top soil.

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How Light Pollution May Be Harming Insects, (treehugger.com), Mary Jo DiLonardo

LED streetlights
LED streetlights at one of the study sites. Douglas Boyes

Head down nearly any street at night and it’s likely to be well-lit. This artificial light at night can have an impact on wildlife migration, as well as animals’ breeding, hunting, and sleeping patterns.1 New research finds nighttime light also may play a role in the declines in insect populations.

Douglas Boyes of the UK Centre for Ecology & Hydrology (UKCEH), who led the study, tells Treehugger.

“Light pollution may be discussed a lot but it’s only relatively recently that we’ve begun to understand just how harmful it can be for wildlife. A growing number of studies are showing it can be detrimental in so many ways—to plants, birds, bats, insects, etc.,”

To study the impact of artificial light on the insect population, Boyes (and his colleagues) spent three years studying moth caterpillars in southern England.

“We focus on caterpillars as these typically don’t move very far in their lifetime, so when sampling at a given point, we can be confident we are precisely measuring local effects (whereas adults are very mobile and may move several kilometers in lifetime).

Moths are highly diverse evolutionarily and ecologically (several thousand species native to Europe), meaning they should be fairly representative of nocturnal insects and are also relatively well-studied. This makes them uniquely placed for understanding the effects of lighting on nocturnal insects more generally.” (Boyes)

For the study, Boyes spent more than 400 hours along roadsides, studying and counting wild caterpillars. Dressed in high-visibility clothing because he often gathered data at night, he visited 27 pairs of sites that were home to two different groups of caterpillars that were easy to sample.

Each pair of sites consisted of a hedgerow or grass margin along the roadside that was lit by streetlights and an identical but unlit habitat. The lit sites included 14 that were illuminated by high-pressure sodium (HPS) lamps, 11 with light-emitting diodes (LED) lamps, and two with older low-pressure sodium (LPS) lamps.

In order to count the insects, Boyes beat hedges in spring and summer to count flying caterpillars and swept the grass with netting to count those that only come out at night to climb on grass to feed.

Of the total 2,478 caterpillars that Boyes counted, the majority of them came from unlit areas.

Artificial lighting reduced the number of caterpillars by somewhere between a half and one-third, the researchers found. Nearly all the lit areas, which had been illuminated for a minimum of five years, had fewer caterpillars.3

Boyes weighed the caterpillars and found they were in general heavier in lit areas, which the researchers suspect is due to stress and is a result of rushed development.

“This will lead to smaller adults, which are less evolutionary fit (lay fewer eggs, etc.),” he says.

In almost all situations, the results were worse under white LED lighting compared to traditional yellow sodium lighting. Boyes points out,

“This is concerning given the ubiquitous transition toward white LED street lighting.”

They also did an experiment where they put up temporary LED lighting in rural grass margins that had never been illuminated before. They found that the feeding behavior of nocturnal caterpillars was disturbed.

“Our separate experiment showed that white LEDs disrupt the normal behavior of nocturnal caterpillars—possibly because white LEDs are quite similar to daylight, so the caterpillars ‘think’ it’s still daytime,” (Boyes)

The findings were published in the journal Science Advance

Researchers examined how their study results might translate into the larger landscape and found that just 1.1% of the land area in the study site is directly lit by streetlights. Suburban areas are frequently illuminated (15.5%) but only 0.23% of arable land and 0.68% of broad-leaved wooded land is lit.

“The evidence suggests lighting is probably not the main cause of insect declines, but clearly can contribute. The main factors are climate change, habitat loss, agricultural intensification, and chemical pollution (including pesticides, nitrogen deposition), but lighting we expect will certainly be important in some contexts.” (Boyes)

The areas that are impacted by lighting keep growing, he points out. Streetlights are not the only cause of light pollution, but the study results can help call attention to the connection of artificial light and potential issues with wildlife.

“They highlight that lighting is a hugely important local influence but one that’s perhaps quite overlooked and/or underappreciated. One of the nice things about working in this field is that there are tractable solutions (compared to climate change which is a much more difficult problem to solve),” (Boyes).

He suggests that LEDs can be modified more easily than sodium lamps, through dimming and using filters to reduce blue wavelengths that are most harmful to insects.

“An ‘insect-friendly’ streetlight would have brightness, perhaps red in color (or at least few blue wavelengths), motion sensors, or dimming when fewest people are around. If possible, though, the best solution that evidence tells us to minimize the harms on insects is to avoid lighting where possible—but of course this is easier said than done.”

As a planning commission, we made it one of our goals to work with developers of lone unit sites or multiple unit sites to minimize lighting and direct it. Much of the emphasis was on being able to see the night sky and keeping light on site rather than infringing into other areas. Blue ray emission was just becoming an issue and was not well known to us then. The suggests of minimizing blue ray emission