Can skyglow reduce nocturnal melatonin concentrations in Eurasian perch?

Area of Science:

• Environmental Science
• Ecotoxicology
• Fish Biology

Background:

• Artificial light at night (ALAN) disrupts natural light-dark cycles, impacting animal physiology and biorhythms.
• Freshwater fish, like Eurasian perch, are susceptible to ALAN from urban and suburban skyglow.
• Limited research exists on fish melatonin response to low-intensity ALAN representative of skyglow.

Purpose of the Study:

• To investigate the sensitivity of Eurasian perch (Perca fluviatilis) melatonin production to low-intensity ALAN.
• To assess the impact of skyglow-level light pollution on fish physiology and circadian rhythms.

Main Methods:

• Eurasian perch were exposed to nocturnal light intensities of 0.01 lx, 0.1 lx, and 1 lx for ten days.
• A control group experienced natural dark nights.
• Melatonin levels were measured non-invasively every 3 hours over a 24-hour period using ELISA.

Main Results:

• Melatonin levels were progressively reduced with increasing ALAN intensity.
• Circadian rhythmicity was maintained across treatment groups, though less consistently at 1 lx.
• Low light intensities (0.01 lx and 0.1 lx) significantly affected perch physiology.

Conclusions:

• Eurasian perch exhibit high sensitivity to ALAN, with low light levels impacting their melatonin production.
• Skyglow in urban and suburban areas can disrupt the physiology of freshwater fish.
• ALAN may interfere with fish sensitivity to lunar cycles and affect temperate freshwater fish biorhythms.