Artificial light at night (ALAN) affects the downstream movement behaviour of the critically endangered European eel, Anguilla anguilla

• Published in: Environmental pollution (1987) 2021-04, Vol.274, p.116585, Article 116585
• Main Authors: Vowles, Andrew S., Kemp, Paul S.
• Format: Article
• Language: English
• Subjects: Anguilla; Animal Migration; Animals; Environmental Pollution; Environmental stressor; Fish migration; Fresh Water; Freshwater conservation; Light pollution; Seafood; Urbanisation
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2021.116585

Artificial light at night (ALAN) is considered one of the most pervasive forms of environmental pollution. It is an emerging threat to freshwater biodiversity and can influence ecologically important behaviours of fish. The European eel (Anguilla anguilla) is a critically endangered catadromous species that migrates downstream to the ocean to spawn in the Sargasso Sea. Given the pervasive nature of ALAN, many eel will navigate through artificially lit routes during their seaward migration, and although considered negatively phototactic, their response has yet to be quantified. We investigated the response of downstream moving European eel to simulated ALAN using a Light Emitting Diode unit in an experimental flume. We presented two routes of passage under: (1) a dark control (both channels unlit), (2) low ALAN (treatment channel lit to ca. 5 lx), or (3) high ALAN (treatment channel lit to ca. 20 lx). Eel were: (i) more likely to reject an illuminated route when exposed to high levels of ALAN; (ii) less likely to select the illuminated channel when given a choice; and (iii) passed downstream more rapidly when the illuminated route was selected. This study quantified the response of the critically endangered European eel to ALAN under an experimental setting, providing the foundations for future field based research to validate these findings, and offering insight on the ecological impacts of this major environmental pollutant and driver of global change. [Display omitted] •An experiment assessed the impact of ALAN on a critically endangered fish.•Fish behaviour was affected by ALAN.•Individuals were less likely to select to pass an illuminated route when given the choice.•Individuals passed downstream faster when the illuminated route was selected. Eel more frequently rejected a route when exposed to simulated light pollution, were less likely to select the illuminated route given a choice and passed faster when the illuminated route was selected.