Light Pollution Killing Insects by the Millions
When night falls, many insects struggle to survive. Street lamps, car headlights, neon signs, floodlights in parking lots, petrol stations and sports facilities, spotlights on construction sites, commercial areas and monuments - such light sources can become death traps for nocturnal insects because they lead to the collapse of their innate ability to orientate themselves.
Of special concern to the Cowichan Estuary, Restoration and Conservation Association (CERCA) are the Lights in the Cowichan Estuary originating from the Cowichan Bay Village, the Western Forest Products (WFP) Mill, and the Westcan Terminal, lightening up the sky 365 nights per year. No impact studies of light pollution on flying insects with their home in the estuary and neighbouring Mount Tzouhalem forest habitats have been conducted to date, and no baseline data on their distribution and relative abundance before these lights were installed are available.
Research data from other estuaries and near-shore habitats suggest that impacts can be extremely severe even leading to local extinctions. Most affected may be Mayflies, stoneflies, and caddisflies often found in estuarine habitats as both larvae and adults. They rely on good quality habitats directly in the water as well as in the terrestrial surroundings to complete their life cycles and sustain healthy populations. All three species provide important ecosystem services that include nutrient cycling, and the prevention of algae and detritus build-up in water bodies by grazing. Their importance in the diet of game fish means that fly-fishers are keenly interested in these groups and this enthusiasm and interest can be harnessed to further promote their conservation.
And not to forget all the other creatures directly and indirectly affected by light pollution in the estuary such as migratory and resident birds, fish and their predators, and many more. Night hawks, where have they gone? Having lived at the estuary for almost 50 years, I can't recall when I last have seen a night hawk in the Bay. Abundant in the seventies and eighties in the Cowichan Estuary, they could be observed any evening in the summer. Is it the lack of nocturnal flying insects, their major prey, which caused them to disappear? Is it the result of light pollution in the estuary causing the death of flying insects? Many open questions still need answers.
But what is the problem?
Despite their tiny eyes and brains, nocturnal insects have evolved a remarkable capacity to visually navigate at night. Whereas some use moonlight or the stars as celestial compass cues to maintain a straight-line course, others use visual landmarks to navigate to and from their nest. These impressive abilities rely on highly sensitive compound eyes and specialized visual processing strategies in the brain.
The problem with many nocturnal insects is that they can still see at unbelievably low levels of light and are attracted to the light. For example, nocturnal butterflies can also perceive the ultraviolet part of the light spectrum invisible to our eye. Research has shown that many lamps that emit UV light as well as visible light, therefore, attract moths and other nocturnal insects particularly strongly and lure them out of their actual habitats in huge flocks.
If insects have discovered an artificial light source, they fly around it until they are completely exhausted, or they collide with the lamp, and are singed and fatally injured in the process. Those who have collapsed from exhaustion often fall victim to their predators. Night hunters such as bats, shrews, toads, ground beetles, and spiders have an easy time with exhausted insects. At daybreak, the birds then clean up under the still frozen insects that are resting on walls or lying on the ground. Entire insect populations in cities or illuminated sites in remote locations can collapse in a short time. The mass extinction of the animals lured to the light cannot be compensated for. Even seemingly natural habitats are becoming so impoverished.
Research has shown that light at the wrong time changes insects' daily and seasonal behavior. In late autumn, insects cannot prepare for winter in time. They don't hole up or they go out foraging at different times than usual. In addition, as our landscape is brightly lit at night, their habitats are cut up and separated from one another. As a result, the animals no longer spread and they cannot conquer new habitats.
According to The Nature Conservation, artificial light sources on the outskirts of settlements, or isolated industrial areas such as in the Cowichan Estuary, have a great attraction for insects. High contrasts between light and dark should therefore be avoided, particularly in the case of free-standing lights that are visible from afar in the evening sky.
Why is that a problem?
Insects are found in almost every habitat, playing major roles in our ecosystems, and are most beneficial to mankind. For many people, insects are of no concern or considered a nuisance to get rid of such as mosquitoes, black flies, blue flies, or wasps. They are unaware of the highly important ecological role such insects play. Wasps and blue flies for example are the police in our environment, helping to keep it clean and healthy. Mosquitos are a major food source for fish and birds, as larvae and adults, providing important ecosystem services that include nutrient cycling, and the prevention of algae and detritus build-up in water bodies by grazing.
According to the Biological Survey of Canada over half of Canada's flowering plants are pollinated by insects, with an economic impact of great importance; without them, the terrestrial portion of our biosphere would be devastated. And without insect pollinators, the world food supply would be in jeopardy. And many of the larger insects serve as basic food for fish, birds, and mammals, constituting a critical link in the food chain.
What we can do and what should be done?
The good news is: Hardly any problem can be solved as easily as light pollution. That is why one of the aims of CERCA's biodiversity initiative is to reduce light pollution in the Cowichan Estuary. WFP, operators on the Westcan Terminal and Cowichan Village, as well as the CVRD, Municipalities, and private individuals have it in their own hands to do without unnecessary lighting and to switch to insect-friendly lighting systems.
A few measures could be taken to stop insect deaths:
Clarify the need for lighting: Not all night-time lighting in public spaces and the estuary is really necessary for safety and/or security reasons. In the case of structural changes, lighting that has become unnecessary should be dismantled.
Technical measures: Light fixtures should be shielded in such a way that the light only gets to where something needs to be illuminated. Light fixtures with a limited beam angle are particularly desirable. Objects should only be illuminated as much as is necessary. A better effect can often be achieved with subdued lighting. In addition, lamps should be used that emit as little short-wave light as possible. Warm white LED lamps that do not emit UV radiation show the lowest attraction effect. Lighting with amber-colored LEDs and reduced brightness protects the environment in two ways: it saves electricity and protects native animals and plants. It is high time to switch to alternative lighting, shorten the duration of the lighting, or, in certain cases, do without night-time lighting altogether.
Light fixture orientation and placement: Each light should always be directed towards the ground. Street and yard lights in particular should be placed in such a way that they do not radiate into the environment or ecologically sensitive spaces.
Time limit: Timers are required for the environmentally friendly operation of lighting. Not every lantern and searchlight has to be on all night. In environmentally sensitive areas such as estuaries, ideally, lighting should be turned off completely after 10 p.m., provided safety regulations permit such a measure.
A fringe benefit from all these remedial measures: if you want to teach your children and grandchildren about stars and the universe you may see the milky road again without driving to the Arctic or Antarctic!
