The research addresses a conspicuous gap in European environmental law. The European Union’s Marine Strategy Framework Directive, introduced in 2008 to protect marine ecosystems and biodiversity, was intended to cover a broad suite of human pressures on the sea, and light pollution was nominally among them. In practice, however, no defined criteria for Good Environmental Status with respect to ALAN have ever been established, which means member states have had no operational way to measure, monitor or manage the problem. Without such criteria, light pollution has remained what the study’s authors describe as a hidden environmental threat, one that is acknowledged in principle but ignored in regulatory terms. The new methodology is designed to close that gap by providing a scientifically grounded, operational and adaptable framework that can be applied with existing knowledge and tools.

Technically, the framework draws on an approach already developed for underwater noise, another form of marine pollution that is extensively covered in existing Marine Strategy Framework Directive guidance. The research team, working as part of the AquaPLAN project, developed separate risk scoring criteria for the water column and for the seabed, recognising that light behaves differently as it travels through clear versus turbid water and that different habitats and organisms are exposed at different depths. The scoring system takes into account the light pollution being emitted by coastal towns and cities, the optical clarity of the seawater in particular locations, and how easily light can penetrate downward through the water column. Where water is clear, artificial light from shore can reach considerably deeper and affect a larger volume of habitat; where it is turbid, penetration is reduced but scattering can still illuminate surface waters.

To produce the risk maps, the team combined these criteria with existing datasets, most notably the 2021 Global Atlas of Artificial Light at Night Under the Sea, which integrates satellite observations of nighttime lights with models of how that light propagates underwater. Each regional sea was then scored according to the percentage of its area exposed to nil, low, medium or high risk of harm. The result is a ranked league table of European sea regions ordered from highest to lowest exposure risk. The Adriatic Sea tops the list, followed by the Baltic Sea and the western Mediterranean Sea, with the Greater North Sea, the Aegean-Levantine Sea, the Ionian and Central Mediterranean Sea, the Black Sea and the Sea of Azov also ranking among the more exposed waters. At the opposite end of the scale sit Macaronesia, a region encompassing the Canary Islands, the Azores, Madeira and Cape Verde, along with the Barents Sea, the Iceland Sea, the Norwegian Sea and the White Sea.

The pattern that emerges is geometric as much as demographic. Enclosed regions bordered by land on several sides accumulate light from multiple densely populated coastlines simultaneously, and because the water cannot disperse or dilute the illumination the way open ocean can, the exposure risk compounds. The Adriatic, wedged between the Italian peninsula and the Balkans and fringed by major tourist destinations, exemplifies the problem. The Baltic, with its low-lying, heavily developed catchment and relatively shallow, partially enclosed basin, shows a similar signature. The western Mediterranean combines intense coastal urbanisation with some of the clearest water in Europe, allowing shore-based light to penetrate further into the water column than it would in murkier northern seas.

For the United Kingdom, the news is comparatively reassuring. The Greater North Sea and the Celtic Seas are largely characterised as being of medium to low risk, reflecting the moderating effect of open connections to the Atlantic and the relatively diffuse distribution of coastal light sources. Yet the assessment also flagged a distinctly industrial contributor: the North Sea’s oil and gas fields, and the infrastructure associated with them, add significant levels of light pollution to what would otherwise be an open ocean setting. Offshore platforms, flares and floodlit installations create islands of artificial brightness far from any coastline, illuminating waters that would naturally experience only moonlight and starlight. This finding underscores that marine light pollution is not solely a coastal phenomenon driven by tourism and urbanisation.

The scientific case for concern has been building for more than a decade. Dr Thomas Davies, Associate Professor of Marine Conservation at the University of Plymouth, led the first ever study into the effects of light pollution on the marine environment in 2014 and is the lead author of the new research. He argues that the accumulated evidence now justifies regulatory action. Over many years, he notes, research has repeatedly shown that light pollution is significantly impacting many important coastal species, yet it remains largely absent from global policy. The Marine Strategy Framework Directive was supposed to include measures linked to light pollution, but that never fully materialised, with the standing argument being that the evidence base was insufficient to support detailed legislation. Davies contends that this argument no longer holds, and that the study, together with the wider body of work since 2014, provides clear evidence of risk and harm that urgently needs to be translated into meaningful action.

Senior author Professor Tim Smyth, Director of Science at Plymouth Marine Laboratory, emphasises that defining and quantifying Good Environmental Status requires more than measurement alone. It depends, he says, on combining global observations and mapping with expert scientific judgement about what a healthy ocean should look like. The 2021 Global Atlas of Artificial Light at Night Under the Sea, together with the extensive evidence generated over the past decade, has made it possible to assess this emerging pressure at a global scale. Smyth frames ALAN alongside other under-regulated stressors such as underwater noise, arguing that together they help build a more complete picture of cumulative human impacts on the ocean and provide the evidence base for effective action ranging from global policy down to local management decisions.

The study was written by scientists from the University of Plymouth, the Centre for Environment, Fisheries and Aquaculture Science, the University of Pisa, the Genoa Marine Centre and the Italian Institute for Environmental Protection and Research, many of whom are also members of the Global Ocean Artificial Light at Night Network, known as GOALANN. The network was launched by Dr Davies and Professor Smyth at the United Nations Ocean Decade Conference in April 2024 and was later endorsed by the UN as one of its Ocean Decade Actions. Professor Elena Maggi, Professor in Ecology at the University of Pisa and AquaPLAN Project Coordinator, describes the central challenge as translating the substantial evidence that artificial light at night affects marine organisms and ecological processes into approaches that identify where ecosystems are most at risk, bringing together ecological knowledge and monitoring to provide a stronger basis for assessment and mitigation.

The authors also point to practical remedies, particularly for the tourist hotspots that dominate the list of most impacted regions. Authorities in those areas could explore meaningful changes to lighting infrastructure, including shielding fixtures to direct light downward, dimming or switching to part-night lighting schemes, and manipulating the wavelength composition of coastal lighting to reduce how far it penetrates into the sea, since blue-rich white light travels furthest through clear water. They further suggest designating dark spaces on and around islands, offering visitors an alternative experience to seasides ringed by artificial illumination. The researchers hope the methodology can be applied globally, and with the Marine Strategy Framework Directive currently under review, they argue the moment is ripe for light pollution to finally be written into European marine law with the same seriousness as noise, nutrients and chemical contaminants.

Subject of Research: A risk assessment framework for artificial light at night pollution in European marine waters

Article Title: Study highlights the European waters at greatest risk of harmful light pollution

Article References: Study highlights the European waters at greatest risk of harmful light pollution. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: light pollution, artificial light at night, marine conservation, Adriatic Sea, Baltic Sea, Mediterranean Sea, Marine Strategy Framework Directive, Good Environmental Status, AquaPLAN, water clarity, coastal ecosystems, University of Plymouth

The submission took an unusual and deliberately democratic form. Rather than speaking with a single voice, AMI combined a survey reflecting the majority view of participating members with a detailed supporting document that sets out the scientific case for greater recognition of marine microorganisms in European ocean policy. The society’s central message is unambiguous: marine microbes must be explicitly recognised as fundamental components of ocean ecosystems, and their needs and contributions must be considered across biodiversity conservation, ecosystem management, ocean-climate policy and the assessment of overall marine health. In other words, an ocean act that only protects what can be seen with the naked eye is, in the view of these scientists, an act that protects only a fraction of what matters.

The scientific rationale for this position is compelling. Microorganisms, including phytoplankton, bacteria, archaea and viruses, drive many of the biological and chemical processes that regulate the ocean. They are responsible for recycling around half of global primary production, a staggering figure that underscores just how much of the planet’s carbon and nutrient throughput depends on organisms too small to see. Through the biological carbon pump, phytoplankton fix carbon dioxide at the surface and export it to the deep sea, while the microbial carbon pump converts dissolved organic matter into long-lived reservoirs that can keep carbon out of the atmosphere for centuries. Microbes also orchestrate the cycling of nitrogen, phosphorus and iron, elements that determine how productive marine food webs can be and how much carbon the ocean can ultimately sequester.

The urgency of this agenda is growing as the ocean changes. As marine waters warm, acidify and lose oxygen, microbial communities are being pushed into conditions they have not experienced on human timescales. Because microbes reproduce quickly and respond rapidly to shifting temperatures, pH levels and nutrient supplies, changes in their community composition and metabolic function often precede visible changes in larger organisms and habitats. Understanding how these communities respond to ocean warming, acidification and deoxygenation will therefore be increasingly important for predicting future shifts in ecosystem function, for anticipating how climate regulation services may weaken, and for designing interventions that support microbial processes capable of buffering environmental stress rather than amplifying it.

Beyond free-living microbes, AMI’s response draws attention to the intimate partnerships between microorganisms and larger marine life. Corals, sponges, seagrasses and fish all exist in close association with complex microbial communities that can influence nutrition, disease resistance and resilience to environmental stress. The coral microbiome, for example, can determine whether a reef survives a bleaching event, while the microbial partners of seagrasses are essential for nutrient uptake in the sediments that anchor these meadows. AMI argues that recognising these host-associated microbiomes could materially strengthen conservation and restoration efforts, by ensuring that the microscopic processes underpinning ecosystem health are not overlooked when protected areas are designated, when species are translocated, or when damaged habitats are actively restored.

There is also a powerful economic argument embedded in the society’s submission. Marine microbial communities represent a largely unexplored reservoir of genetic and biochemical diversity, a living library of molecules shaped by billions of years of evolution in some of the most extreme environments on Earth. Potential applications range from novel medicines and industrial enzymes to new biomaterials and biotechnological processes, with microbial enzymes from cold-adapted and pressure-tolerant species already finding uses in industry and research. AMI stresses that protecting marine microbial biodiversity is therefore not only an environmental priority but also an investment in future innovation, feeding directly into the ambitions of the European blue bioeconomy and the continent’s broader strategy for sustainable growth grounded in living resources.

Translating this science into law, AMI offers a series of concrete recommendations. First, the society calls for strengthening the definition and assessment of Good Environmental Status, the benchmark against which European seas are measured, so that it explicitly considers microbial diversity, community composition, functional diversity and the ecosystem services that microbes provide. Second, the submission urges that host-associated microbiomes be formally recognised wherever they are important to the health and resilience of protected species, habitats and ecosystems. These changes would mean that monitoring programmes, conservation targets and restoration criteria under the Ocean Act would no longer treat microbes as an afterthought but as measurable, reportable components of environmental quality in their own right.

The response also argues that an ecosystem-based approach to ocean management must move beyond a focus on visible organisms and iconic habitats. Microorganisms drive the processes that make marine ecosystems possible, including nutrient cycling, carbon sequestration, primary productivity and decomposition. Their rapid responses to environmental change could provide early-warning indicators of ecosystem condition and recovery, offering policymakers near-real-time signals of stress long before fish stocks decline or habitats collapse. Incorporating microbial indicators into routine monitoring would give regulators a finer-grained, more responsive picture of ocean health, and could reveal whether management measures are actually working at the functional level where the ocean’s essential chemistry is performed.

By bringing together the expertise and perspectives of its global membership, AMI is advocating for an Ocean Act that recognises the full biological complexity of marine ecosystems and puts microbiology firmly within Europe’s vision for a healthy, resilient and sustainable ocean. The society, the oldest microbiology society in the United Kingdom with more than half of its members based outside the country, publishes The Microbiologist magazine and three internationally recognised journals in partnership with Oxford University Press, and it frames this intervention as part of its wider mission to amplify the collective influence of applied microbiologists in evidence-based decision making. The consultation response makes clear that the microbes drifting in every litre of seawater are not a footnote to ocean policy; they are its scientific foundation, and the legislation that will govern European seas for decades should say so explicitly.

Subject of Research: The role of marine microorganisms in European ocean policy and the proposed EU Ocean Act

Article Title: AMI calls for marine microbes to be at the heart of Europe’s future ocean policy

Article References: AMI calls for marine microbes to be at the heart of Europe’s future ocean policy. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: marine microbes, EU Ocean Act, Applied Microbiology International, ocean policy, microbial carbon pump, Good Environmental Status, blue bioeconomy, host-associated microbiomes, ocean acidification, biodiversity conservation, ecosystem monitoring, phytoplankton