Clownfish reproduction threatened by artificial light in coral reefs

JULY 10, 2019

by Flinders University

The popular story about a clownfish that got lost at sea in the movie Finding Nemo could have a much darker sequel—as artificial light in coral reefs leaves the famous fish unable to reproduce offspring, according to a new study.

Results from a new study published in Biology Letters show an increasing amount of artificial light at night (ALAN) in coral reefs, even at relatively low levels, masks natural cues which trigger clownfish eggs to hatch after dusk.

Lead author Dr. Emily Fobert, Research Associate in biodiversity and conservation at Flinders University, says test eggs that were incubated in the presence of artificial light had a zero success rate of hatching, with no offspring surviving as a result.

"The overwhelming finding is that artificial light pollution can have a devastating effect on reproductive success of coral reef fish," says Dr. Fobert

"When ALAN is present, no eggs hatched but when the light was removed during the recovery period, eggs from the ALAN exposure hatched like normal, so the presence of light is clearly interfering with an environmental cue that initiates hatching in clownfish."

"The results indicate increasing amounts of light have the potential to significantly reduce the reproductive fitness of reef fish who settle in a habitat near shore lines."

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Nightlights for stream dwellers? No, thanks

Date:  December 19, 2018

Source:  Ohio State University

Artificial light at night isn't just a health problem for those of us sitting in bed scrolling through Instagram instead of hitting the sack -- it hurts entire outdoor ecosystems.

When the critters that live in and around streams and wetlands are settling into their nighttime routines, streetlights and other sources of illumination filter down through the trees and into their habitat, monkeying with the normal state of affairs, according to new research from The Ohio State University.

"This is among the first studies to show that light at night has detrimental effects not just on individual organisms in the environment, but also on communities and ecosystems," said Mažeika Sullivan, lead author of the study, which appears today (Dec. 19, 2018) in the journal Ecological Applications.

"Nighttime light is having profound impacts that extend to the entire ecosystem," said Sullivan, director of Ohio State's Schiermeier Olentangy River Wetland Research Park and associate professor of environment and natural resources.

Though many people might not consider it, artificial light is a pollutant, changing the natural course of life for people, animals and plants, he said, adding that urbanization is rapidly increasing both in the United States and around the globe.

"We are experiencing this pollution that we don't think about, but it's all around us and it's chronic and it's happening everywhere -- from newly lit villages in rural Africa to streams alongside the highway in Columbus, Ohio," he said. "It's also unprecedented in Earth's history."

The new study explored the role of light on streams and wetlands in and around Columbus. Moonlight under a clear sky can give an illuminance of 0.1 to 0.3 lux, Sullivan said. The streams in the study were headwater streams draining into the Scioto and Olentangy rivers, with light ranging from 0.01 to 4.0 lux. Wetlands of the Olentangy River Wetland Research Park had lighting from 0 to 20 lux.

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Red light has no effect on bat activity: Less disruption by changing artificial color

Date: June 2, 2017

Source: Netherlands Institute of Ecology (NIOO-KNAW)

 

Artificial light at night can have a disruptive effect on bats, but not if the light is red. Switching to red light may therefore limit or prevent habitat loss for rare, light-shy bat species. The latest issue of Proceedings of the Royal Society B publishes results from five years of pioneering research led by the Netherlands Institute of Ecology (NIOO-KNAW).

It's the first time researchers have succeeded in measuring the effects of light with different spectra on the activity of slow-flying, light-shy bats in their foraging habitat. "We've found these bats to be equally active in red light and darkness," says principal researcher Kamiel Spoelstra. "White and green light, on the other hand, substantially reduce the bats' level of activity."

The effect of red light on more common bat species such as the pipistrelle is reduced as well. Unlike a strong increase in activity of this species in white and green light, the activity in red light is comparable to darkness. This is caused by the strong attraction of insects to white and green (and not red) light. Pipistrelles opportunistically feed on these accumulated insects.

Real-life conditions

"The lack of effect of red light on both the rarer, light-shy species and the more common non-light-shy bats," concludes Spoelstra, "opens up possibilities for limiting the disruption caused by external, artificial lighting in natural areas, in situations where having light is considered desirable."

 

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Scientists measure impact of artificial light on sea turtles

May 19, 2016

Research carried out by The University of Western Australia, the Australian Institute of Marine Science and the Department of Parks and Wildlife has found new evidence that there is an impact from artificial light on the survival of wild sea turtle hatchlings.

Using the latest micro-technology, the scientists tracked the movements of green turtle hatchlings (Chelonia mydas) for the first time, as they moved through the water near the shore of the Ningaloo Reef in Western Australia.

The research found that 90 per cent of the tracked hatchlings swam towards the artificial light thinking it was the moon and becoming disorientated in their journey offshore.

UWA Professor of Coastal Oceanography Charitha Pattiaratchi said the scientists measured oceanographic parameters during the experiments that enabled them to isolate the effects of the artificial light on the hatchlings by looking at the effects of ocean currents.

"It is widely known that artificial lighting near turtle nesting beaches attracts turtle hatchlings as they emerge from nests and can cause them to have trouble finding the sea," Professor Pattiaratchi said.

"But understanding what happens once they reach the sea and how lights on water from sources such as boats, ports and wharves affect them has been unknown up until now because we lacked a simple means to track them."

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