Editor’s note: Artificial light at night (ALAN) whose undesirable effects are more colloquially referred to as light pollution – has long been known to affect sea turtles. Numerous studies document that adult sea turtles avoid nesting on artificially-lit beaches and artificial lights on land draw newly-hatched sea turtles away from the ocean, leading to increased mortality due to increased predation, dehydration and energy expenditure. But what about other marine organisms? In this article, we explore (Skimmer-style) recent research about how light pollution may be affecting many marine organisms and ultimately marine ecosystems.

Natural light cues structure a lot of behaviors and processes in marine ecosystems

Coastal light pollution is global and getting worse

Artificial light at night (ALAN) interferes with marine ecosystem processes


A conceptual map of individual- to ecosystem-level responses to ALAN

A conceptual map of individual- to ecosystem-level responses to ALAN in estuarine ecosystems by Zapata et al. (2019) classifies responses by level of organization.

  • At the individual level, ALAN can impact physiology and behavior by increasing, decreasing, and/or altering diel and nocturnal activity.
    • Mechanisms for this occurring can include changes to visual sensitivity, circadian rhythms, predation risk, food availability, and stress and reproductive hormone levels.
  • At the population level, ALAN can impact performance by shifting diel or nocturnal activity which may enhance or reduce fitness.
    • Mechanisms for this occurring can include lit areas serving as polarized or direct light traps or light expanding or constraining activity intervals.
  • At the species level, ALAN can impact interactions by altering predation and competition among diurnal and nocturnal taxa.
    • Mechanisms for this occurring include changes to the spatial, spectral, and temporal composition of light and the spatiotemporal distribution of food resources and habitat.
  • At the community level, ALAN can impact composition by changing relative abundance, species diversity, and distribution of taxa.
    • Mechanisms for this occurring include changes to the availability and partitioning of resources, risk regimes, and movement and dispersal patterns.
  • At the food web level, ALAN can impact structure by restructuring trophic network topology and functional attributes.
    • Mechanisms for this occurring include altering interaction strengths via spatial and temporal shifts and changing aquatic primary productivity.
  • At the ecosystem level, ALAN can impact function by changing nutrient cycling, biodiversity, and ecosystem productivity.
    • Mechanisms for this occurring include changes to cross-boundary nutrient flows.
  • Changes at any of these levels of organization (e.g., individual, population, species, community, food web, and ecosystem) can in turn impact other levels of organization (e.g., individual responses can cause population and community level impacts).

Text from Zapata, M.J., Sullivan, S.M.P. and Gray, S.M. Artificial lighting at night in estuaries – Implications from individuals to ecosystems. Estuaries and Coasts 42, 309–330 (2019). https://doi.org/10.1007/s12237-018-0479-3


Furthering ALAN research in marine ecosystems

Furthering ALAN policy for marine ecosystems


Photo credit: Lights of Vancouver, British Columbia, Canada, as seen from Stanley Park by Seán Ó Domhnaill.