Photos: Research into the impacts of Artificial Light At Night (ALAN) on marine ecosystems is still at a fledgling state. Extensive coastal installations continuously shine artificial light on our seas
Marine ecosystems are bearing the brunt of multiple stressors, including the enrichment of coastal waters, sea warming, underwater noise, habitat destruction and degradation through anchoring and the construction of coastal facilities, the occurrence of microplastics, overexploitation and others. Most recently, the influence of light pollution on the same ecosystems, especially at night, has emerged as yet another stressor which needs to be investigated. So much so that a corresponding acronym – ALAN (Artificial Light at Night) – has been coined to describe the phenomenon. ALAN can be generated from both coastal facilities (ports and harbours, promenades, hotels) as well as from offshore ones (bunkering areas, aquaculture facilities).
Francesca Grillo, a 2023/2024 Masters of Science in Applied Oceanography graduate, chose to investigate the influence of ALAN on local marine ecosystems for her course dissertation, through a preliminary study conducted at Cirkewwa, which features continuously-lit and darkened submerged environments. Francesca was supervised by Prof. Alan Deidun, coordinator of the MSc in Applied Oceanography course, as well as by Dr Adam Gauci, core lecturer within the same course. Mr Alessio Marrone, an RSO within the Oceanography Malta Research Group (OMRG) which offers the course in question, also assisted in the study through his expertise in field sampling and statistical approaches.
Francesca’s study was innovative not just in terms of the selected thematic but also in terms of the equipment it made use of – namely, a BRUV (Baited Remote Underwater Video), which attracts marine biota through the use of bait under different lighting conditions. During August 2023, a total of eighteen video samples were collected, using three light treatments (High-White Light Intensity (H), Low-White Light Intensity (L), and Red Light (R)) across two Habitats (Harbour and Reef), with three replicates per treatment. The specified light settings for each treatment were achieved using torches attached to the BRUV system.
The study’s key findings indicate that some habituation occurred, as seen in the bogue (Boops boops), which did not exhibit typical schooling behaviour under low-light intensity in the harbour. Predatory species, particularly Atlantic horse mackerel (Trachurus trachurus) strategically exploited high-light conditions, demonstrating station-holding behaviour, primarily under high-intensity white light, due to net energy gain despite increased metabolic costs. Species at lower trophic levels, such as the Mediterranean cardinal fish (Apogon imberbis) declined in abundance as light intensity increased, whilst the common cuttlefish (Sepia officinalis) and the bearded fireworm (Hermodice carunculata) also showed a preference for darker environments.
MSc in Applied Oceanography students are always encouraged to publish research conducted through their course dissertation. Besides Francesca’s publication on ALAN, earlier this year, yet another course student – Benjamin Mifsud – published the outcomes of his dissertation within which he designed an image analysis algorithm (the Aquavision one) which automatically identifies invasive alien fish species from photos submitted to citizen science campaigns.
The AI-based fish-identification publication can be accessed online.
