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Light pollution takes a toll on the aquatic food web

An experiment on Slate Run in Columbus, Ohio found that light pollution affects the aquatic food web.

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The safety of the water is no protection against the effects of artificial light, finds a study recently published in Ecological Applications. Adding light to a stream in Ohio changed the abundance of invertebrates such as spiders and insects.

Scientists have been documenting an ever-increasing list of effects from light pollution. Insects, for instance, can directly be killed by hot lamps. Or there might be more predation of them — bats have been spotted feasting on bug buffets near artificial lights. Other animals, including us, can have their circadian rhythms disrupted.

Those effects can have a cascade of impacts throughout an ecosystem. To determine what those might be in a stream, Lars Meyer and Mazeika Sullivan of Ohio State University set up an experiment on Slate Run, an offshoot of the Scioto River near Columbus, Ohio. After measuring light levels in urban areas adjacent to streams — including restaurants, sports arenas and roads — the team flooded areas of the stream with similar levels of light at night. Weeks later, they collected emergent insects and terrestrial arthropods and surveyed spider webs, comparing those collections to ones made before the addition of artificial light.

In the lighted areas, Meyer and Mazeika found a 44 percent decrease in one family of orb-weaving spiders, a 76 percent decrease in the body size of emergent insects and a 309 percent increase in the size of terrestrial arthropods. That last category includes predators and scavengers such as rove beetles and wolf spiders that, like bats, may be attracted to lit areas where they can munch on the abundance of invertebrates that are directly drawn to the light.

The decrease in body size of emergent insects might also be the result of predation, the team writes. Many of the fish species that feast on insects are visual predators, they note, and would probably eat the biggest insects they can see, thus pulling them out of the food web and the scientists’ collection efforts.

As for the spiders, well, they seem to lose out on several levels. Artificial light is helpful for terrestrial predators such as birds, and spiders may be losing prey to competitors. The higher levels of light may make it harder for spiders to hide, leaving them more vulnerable to getting eaten. And to make life even harder for the spiders, high light levels might make the ventrum spots some species use to lure prey less effective. Artificial light is definitely not a spider’s friend.

“As the world’s populations continue to urbanize, the potential for [ecological light pollution] to influence communities and ecosystems at broader spatial scales also increases,” the researchers write. There’s still a lot of research that has to be done to figure out exactly how artificial light is affecting the world’s ecosystems, but there’s enough evidence at this point to realize that light is really messing up a lot of organisms.

The giraffes that sailed to medieval China

Chinese exploration of the world is often left out of Western textbooks (at least it was left out of mine), but for a brief period, from 1405 to 1433, the Chinese under Ming emperor Yongle sent out numerous trade missions that reached as far as present-day Kenya. During the fourth expedition, which left China in 1413, part of the fleet led by commander Zheng He sailed to Bengal in India, where in 1414 they met envoys from the African coastal state of Malindi (now part of Kenya). The men from Malindi had brought with them as tribute giraffes, and they gave one of those giraffes to the Chinese, who took it home.

Roadkill prevention could save a species from more than just your car

Roadkill can be disgusting, a menace to your car or even dinner. For millions of animals, though, an attempt at crossing the road ends in death for them (and for a couple hundred humans in the cars that hit them). For some animal species, these collisions can actually be the factor that tips the population down the path to extinction.

The bottom feeding behavior of humpback whales

If you go on a whale watching tour, you might be lucky enough to catch humpback whales feeding. Sometimes they slap their tail flukes on the surface, frightening their fishy prey so they school, making the fish easier to eat.

Rhino beetle horns come cheap

If you don’t like bugs* or other creepy crawlies, rhinoceros beetles are not for you. But these insects are marvelous critters, remarkable for both their large size and the interesting shapes of their bodies.

Some elephants get the point

Not all animals understand what a human means when he points at something. Dogs get it, as do several other domesticated animals. Now we can add African elephants to that list.

Eliminating prairie dogs can lead to desertification

Prairie dog haters, be warned: Removing the species you consider a pest could ruin delicate lands.

Mama bird tells babies to shut up, danger is near

Sending up the alarm when a predator approaches seems like a good idea on the surface. But it isn’t always, because such warnings might help the predator pinpoint the location of its next meal. So animals often take their audience into account when deciding whether or not to warn it of impending danger. And a new study in Biology Letters finds that the vulnerability of that audience matters, at least when we’re talking about baby birds and their parents.

An ammonite adventure on the Jurassic Coast

This region is special because fossils are easy to find. They wash out of the cliffs and onto the beach where they are free for anyone to collect, as long as you follow the rules.

Maybe Britain shouldn't kill its badgers

A study on badger social networks shows that isolated badgers are the ones that most often carry TB and cause infections among — but not within — groups.

The bromance of the fossas

Male fossas, mammal carnivores native to Madagascar, hang out with other males to boost their hunting and mating success.
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