IndicatorS Of changing Lightscapes in Underwater Marine Ecosystems (ISOLUME)

Investigating how marine lightscapes have changed over recent decades, what is driving these changes, and how they affect marine ecosystems
Tokyo's Rainbow Bridge at twilight

IndicatorS Of changing Lightscapes in Underwater Marine Ecosystems (ISOLUME)

Investigating how marine lightscapes have changed over recent decades, what is driving these changes, and how they affect marine ecosystems
Title: IndicatorS Of changing Lightscapes in Underwater Marine Ecosystems (ISOLUME)
Funding amount: €2.3 million
Location: Pan-European (European seas, coastal zones and freshwater–marine systems)
Dates: July 2025 – June 2028
Project partners: Leibniz Institute for Baltic Sea Research Warnemünde (Coordinator); University of Plymouth; Plymouth Marine Laboratory; University of Galway; Norwegian Institute for Water Research; University of Bergen; Institute of Oceanology Polish Academy of Sciences; University of Malta; Leibniz Institute of Freshwater Ecology and Inland Fisheries; Brandenburg University of Applied Sciences; University of Greifswald
University of Plymouth PI: Dr Thomas Davies 
 

Overview

Marine light environments are changing rapidly due to two major but poorly understood pressures: coastal darkening and artificial light at night (ALAN). Coastal waters are becoming darker due to increased particles, dissolved organic matter and phytoplankton, while artificial lighting from coastal infrastructure is brightening the night-time ocean. Together, these changes are transforming underwater lightscapes across European seas.
ISOLUME is an international research project investigating how marine lightscapes have changed over recent decades, what is driving these changes, and how they affect marine ecosystems. By combining long-term observations, satellite data, modelling and ecological analyses, the project will provide the most comprehensive assessment of changing marine light environments to date.
The project will also develop monitoring tools and policy frameworks to help manage changing light conditions and support healthier marine ecosystems.

Objectives

  • Quantify long-term changes in marine lightscapes across European seas
  • Identify the drivers of coastal darkening and artificial light at night
  • Understand how changing light environments affect marine ecosystems, including productivity and phenology 
  • Develop monitoring frameworks and indicators for marine lightscapes
  • Provide policy guidance and mitigation strategies for managing changing light environments 
  • Maximise societal and policy impact through stakeholder engagement and outreach.

Changing marine lightscapes are an emerging but overlooked environmental challenge. ISOLUME will provide the scientific evidence and tools needed to understand and manage how light in the ocean is changing.

Thomas DaviesDr Thomas Davies
Associate Professor of Marine Conservation

Context of the issue

Light is a fundamental driver of life in the oceans, shaping biological rhythms, productivity and ecosystem functioning. However, marine lightscapes are being altered by two major human-driven processes: coastal darkening and artificial light pollution.
Coastal darkening occurs when increasing concentrations of suspended particles, dissolved organic matter and phytoplankton reduce water clarity, limiting light penetration. At the same time, artificial lighting from coastal cities, ports and offshore infrastructure is increasing the extent and intensity of artificial light at night in marine environments.
Despite growing evidence of these trends, their combined impacts on marine ecosystems remain poorly understood. Key knowledge gaps include long-term trends, the relative importance of different drivers, and how changes in light regimes affect biological processes such as primary production, habitat quality and seasonal timing of ecological events. 
These gaps limit the ability of policymakers and environmental managers to incorporate changing light conditions into marine monitoring, conservation and planning frameworks.

How the project addresses the issue

ISOLUME brings together an interdisciplinary international consortium to provide the first comprehensive assessment of changing marine lightscapes across European seas. The project combines satellite observations, long-term in situ measurements and advanced modelling to reconstruct how underwater light environments have evolved over decadal to centennial timescales. 
By analysing both large-scale patterns and regional case studies, ISOLUME will identify the key drivers of change, from climate variability and land–sea interactions to technological shifts in lighting. It will also quantify ecological impacts, including changes to marine productivity, habitat suitability and biological timing in key species. 
Crucially, the project integrates environmental law, policy and stakeholder engagement to translate scientific insights into practical outcomes. Outputs will include monitoring frameworks, mitigation strategies and a roadmap for incorporating marine lightscapes into environmental policy and ocean observing systems. 
Together, these advances will help establish changing marine lightscapes as a new indicator of ocean health and support more effective marine management across Europe.

Marine light pollution

Understanding and managing the impact of artificial light at night (ALAN) for healthy seas
Artificial light at night (ALAN) is of growing concern as a pollutant to our seas. It disrupts the natural patterns and biological processes of marine life, including those that support critical ecosystem services. This includes animals' ability to see their environment – to hunt, hide, communicate, navigate, grow, time important events and reproduce.
The impacts of light pollution on the night sky, astronomy and land-based ecosystems are well studied – but until just over 10 years ago, the full extent of ALAN in our coastal waters, seas and oceans was unknown.
Artificial light at night on the coast of Liguria with light pollution in sea water