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Low levels of artificial light at night disrupt the daily rhythms of the oyster Crassostrea gigas

Circadian Biology Weekly Brief ↗PubMed ↗DOI ↗

Updated Jan 12, 2026

Abstract

Artificial light at night (ALAN) disrupts the daily rhythm of the oyster Crassostrea gigas at exposure levels starting from 0.1 lx.

ALAN increases valve activity in oysters, indicating a disturbance in their daily behavior.
The differences in gene expression related to the circadian clock are eliminated under ALAN exposure.
Effects of ALAN are observed even at low light levels comparable to artificial skyglow.
Disruption of biological rhythms in oysters may lead to significant physiological and ecological impacts.

Simplified

Artificial Light At Night (ALAN) masks the natural light cycles and thus can disturb the synchronization of organisms' biological rhythms with their environment. Although coastlines are highly exposed to this growing threat, studies concerning the impacts of ALAN on coastal organisms remain scarce. In this study, we investigated the ALAN exposure effects at environmentally realistic intensities (0.1, 1, 10, 25 lx) on the oyster Crassostrea gigas, a sessile bivalve subject to light pollution on shores. We focused on the effects on oyster's daily rhythm at behavioral and molecular levels. Our results showed that ALAN disrupts the oyster's daily rhythm by increasing valve activity and annihilating day / night differences of expression of circadian clock and clock-associated genes. ALAN effects occur starting from 0.1 lx, in the range of artificial skyglow illuminances. We concluded that realistic ALAN exposure affects oysters' biological rhythm, which could lead to severe physiological and ecological consequences.

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Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

PubMed

Low levels of artificial light at night disrupt the daily rhythms of the oyster Crassostrea gigas

Abstract

Full Text

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Competing interests

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Abstract

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