Light pollution impacts ecological communities

Artificial light harms ecological communities by directly affecting key species

Many plants, animals and other organisms are harmed by light pollution. Harms include death, injury, reduced nutrition, changes in behaviour and mistimed growth and reproduction.

All species in an ecological community rely on each other

Effects of lighting on one species have consequences for other species as they depend on each other for food, shelter or reproduction.

Illustration of an hole swooping on a mammal hiding in a hollow which is illuminated by light

Artificial light reduces pollination, seed dispersal and nutrient cycling

Reproduction in many native plants relies on nocturnal pollinators and seed transporters, including bats, moths, possums, ants and native rats. Plants also depend on a network of animals, fungi and bacteria to process soil nutrients and maintain soil structure. Artificial light can reduce native plant growth, reproduction and fruit production by:

  • distracting, repelling or killing pollinators, reducing flower visits and the amount of pollen transported
  • restricting the movement of seed-dispersing animals across the landscape
  • reducing nutrient cycling by soil-digging nocturnal mammals (such as bandicoots, bettongs and bilbies)
  • reducing the activity of invertebrates that break down dead organic material (such as beetles, marine amphipods and saltmarsh crabs).

Light pollution changes food webs

Artificial light changes the way predators and their prey interact, including by:

  • Causing prey to gather around light sources - reducing dark refuges for prey
  • Helping visual predators to detect prey (or vice versa)
  • Making prey less active in illuminated areas - enabling daytime predators to hunt at night.

For plant-eaters, light pollution can reduce food availability by changing the timing of plant reproduction, growth, flowering and fruiting.

An ‘ecological community’ is any group of plants, animals and other organisms that occur together and depend on each other. Around 100 unique ecological communities are listed as threatened under the Environment Protection and Biodiversity Conservation Act 1999. Ecological communities support clean air and water, keep soils healthy, control erosion and salinity, store carbon and underpin Australia’s native biodiversity.

Ecological communities are already under pressure from climate change, land clearing, invasive species, pollution and changes to fire behaviour and water availability. Light pollution imposes additional stress on already threatened communities.

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Light pollution fragments habitats

Isolated populations of plants, animals or other organisms are at risk of extinction due to inbreeding or disturbance (fire, flood, drought, storms). Ecological connectivity allows organisms and their genes to travel across the landscape and water bodies. This ensures genetic diversity and allows habitat to be re-occupied following disturbance.

Human infrastructure – including cleared land, roads, dams and marinas – creates barriers to movement and reduces connectivity. This is a key reason many ecological communities in Australia are threatened.

Many nocturnal animals, including bats and other small mammals, frogs, insects, birds and marine animals cannot cross artificially illuminated areas. Artificial lighting along roads, paths or jetties can fragment surrounding habitat, isolating populations on either side.

Dark corridors that break up stretches of artificial lighting can improve connectivity between habitat patches.

Invasive species benefit from artificial lights

Artificial light benefits invasive species by providing additional resources and excluding native wildlife:

  • Feral cats and red foxes have greater hunting success under artificial light
  • Cane toads and common house geckos benefit from insect concentrations around outdoor lights
  • Rainbow lorikeets (invasive in some states) prefer roosting in illuminated trees
  • Some invasive plants are better than native plants at using artificial light to grow and spread.

Tolerance of human disturbance (including lighting) helps invasive species to out-compete less tolerant native species.

How you can help

  • Consider the potential effects of artificial light on all species present in a community – including native plants, insects and exotic species.
  • Remember: some effects will be indirect and take time to appear.
  • Consider how the landscape, vegetation and seasons will influence the spread and impact of artificial light.
  • Avoid lighting installations that fragment habitat, or disrupt existing connectivity between habitat patches.
  • Protect dark refuges and corridors to improve landscape connectivity.
  • Implement the 6 principles of best practice lighting design.
Illustration of a cat sneaking up on a bird illuminated by lights from a nearby house