Blinded by the light: the effects of urban lighting on beach bugs

A new study further enhances the University's reputation as a global leader on the ecological effects of light pollution
Sandhoppers feeding on seaweed

A group of international scientists – including two from the University of Plymouth and Plymouth Marine Laboratory (PML) – has developed a new method for examining the effects of Artificial Light at Night (ALAN) on two sandy beach crustacean species.
The study focused on sandhoppers (Orchestoidea tuberculate) and beach pillbugs (Tylos spinulosus), using tiny slices of their tissue and powerful microscope techniques to measure these species' visual systems and assess damage caused by artificial lighting.
In isopods such as the beach pillbug, which are naturally adapted to dimmer night lighting compared to amphipods like sandhoppers, the light-sensitive part of the eye (rhabdom) is 20 times larger and includes a reflective layer called a tapetum, which helps species in low-light environments.
A short exposure to artificial light caused between three and six times more damage to the beach pillbug’s rhabdom compared to the sandhopper's, with no recovery after as much as 24 hours.
The isopod's rhabdom showed structural damage, while the amphipod's rhabdom was unaffected, suggesting that species adapted to darker environments are more severely and permanently affected by artificial light, potentially creating new challenges for their survival and evolution.
The study is published in the journal Science of the Total Environment, and was led by researchers from the Universidad Andrés Bello in Chile.
The researchers say its novel methodology has provided unprecedented insights into the microscopic world of marine crustacean photoreceptors, suggesting that ALAN can result in the disruption of natural behavioural patterns and potential genetic modifications in light-sensitive species.

While the extent and ecological impacts of light pollution are increasingly well understood in the marine environment, current research is often restricted to measuring changes in the behaviour of organisms or how they are assembled within a habitat.

This study provides evidence of the direct damage caused by light pollution to the visual capabilities of an animal. Not only does it highlight how light pollution causes harm to marine species directly, but it also raises new concerns around the impacts of lighting associated with deep sea exploration and development. These regions of our oceans experience little or no light and so many animal visual systems are likely to be very sensitive to low light conditions and more easily damaged by lights that otherwise wouldn’t be there.

Thomas DaviesDr Thomas Davies
Associate Professor of Marine Conservation

We already know that artificial light is detected at around a quarter of the world’s coasts and will dramatically increase as coastal human populations more than double by the year 2060. This latest study shows the devastating potential effects it can have on tiny creatures found along the shoreline, which are important food sources and habitat engineers, and how urban lighting can fundamentally alter their sensory systems.

Professor Steve Widdicombe
Director of Science, Plymouth Marine Laboratory (PML)
The University and PML have partnered on a number of pioneering studies into the impacts of marine light pollution in recent years.
In April 2024, they launched the Global Ocean Artificial Light at Night Network (GOALANN) at the United Nations Ocean Decade Conference in Barcelona, aiming to unify research groups from around the world to provide a central resource of marine light pollution expertise, projects and tools.
  • The full study – Miranda-Benabarre et al: Crustacean photoreceptor damage and recovery: Applying a novel scanning electronic microscopy protocol in artificial light studies – is published in the journal Science of The Total Environment, DOI: 10.1016/j.scitotenv.2024.177561.

Marine light pollution

Dr Thomas Davies has been driving the strategy for marine light pollution research - and mobilising policy action - since he led the first study on the topic in 2014.
In collaboration with colleagues in the UK and abroad, he continues to combine laboratory and field experiments with remote sensing to deliver insights into how changing lightscapes impact marine organisms and ecosystems.
Artificial light at night on the coast of Liguria with light pollution in sea water

Study BSc (Hons) Marine Biology

In this hands-on degree you’ll explore the organisms living in marine environments from the coastal margins to the deep sea. Teaching takes advantage of the stunning coastline on the doorstep of the University as well as some of Europe’s best marine facilities, so you won’t just experience marine biology but also practise it at the highest levels, both in the laboratory and field.
Aerial view of blue lake with a fishing boat and green forests with rocks in Finland. Getty
 
Aerial view of Plymouth Sound

Marine Research Plymouth

Man fishing in small boat above coral reef. 

Marine Conservation Research Group

Close-up wave

Marine Institute