ALaNoR – Artificial Light at Night on Reefs

Artificial light at night is a globally widespread environmental pollutant with direct ecological impacts on all levels of biological organisation across both terrestrial and aquatic ecosystems. Approximately one-tenth of the world’s population (600 million people) live in coastal areas that are less than 10 m above sea level, resulting in considerable anthropogenic light pollution, which is expected to increase in parallel with global human population increases along the world’s coastline. While light pollution is a recognised threat to terrestrial wildlife and biodiversity worldwide, directly affecting biological and ecological processes across taxa, including changes in key life-history traits, such as immune function, survival, aging and fecundity, the impacts of ALAN have rarely been assessed for marine species in the wild.

Artificial light at night likely impacts many marine species which have evolved biological rhythms based on natural light cycles, the strongest and most predictable of environmental cues. Cues from circadian, circalunar, seasonal and annual rhythms are vital for biological processes such as reproduction, and dispersal. Natural light regimes may be compromised by ALAN, directly disrupting physiology, behaviour and reproduction in many marine organisms. Despite the potential for ALAN to strongly disrupt such processes, only two laboratory studies have been undertaken to date, meaning the impacts of ALAN on coral reefs remains largely unexplored. A recent collaborative long-term field study led by the two Principal Investigators found that ALAN reduced juvenile clownfish survival and growth. As the light pollution was representative of levels recorded on fringing reefs, but less than in ports, impacts on marine ecosystems are likely even greater, and research in this area is desperately needed.

The aim of these PhD projects is to quantify the fitness consequences of exposure to ALAN on adult reproduction, egg traits and larval traits associated with dispersal. Reproduction and dispersal are vital processes for population persistence and determining how they are impacted by ALAN is essential for managing light pollution and conserving biodiversity on fringing coral reef ecosystems.

The CNRS project will investigate how artificial light at night impacts on spawning behaviour, spawner physiology, reproductive phenology, and larval traits in coral reef fishes.

The University of Melbourne project will investigate how artificial light at night (ALAN) impacts on larval settlement, post-settlement growth and survival, recruitment, and self-recruitment of coral reef fishes.