Artificial skyglow at night disrupts biological rhythms and physiology in Pacific oysters, according to a study published by Nature.
Researchers conducted a one-year field study in Arcachon Bay, France, to investigate the impact of artificial skyglow at night on coastal organisms. The team focused specifically on the Pacific oyster, scientifically known as Crassostrea gigas. Urban lighting creates widespread light pollution in coastal environments, a phenomenon that remains largely understudied regarding its long-term effects on marine life.
The study tracked how nocturnal illumination alters both daily and seasonal biological processes. Oysters rely heavily on natural light cues to regulate essential survival mechanisms. When artificial skyglow interferes with these cues, the physiological consequences extend across multiple biological systems.
The results demonstrate that artificial light at night affects oysters’ behavioral valve activity rhythms. This disruption occurs regardless of whether the rhythms are directly driven by light cycles—such as daily, lunar, and annual patterns—or by independent cycles like tidal and semi-lunar movements. These findings point directly to a broader disruption of the oyster’s internal biological clock.
Behavioral valve activity dictates feeding and respiration rates in bivalves. When artificial skyglow alters these opening and closing patterns, the animal’s baseline energy expenditure shifts. Such chronobiological disruption compromises the organism’s overall physiological stability.
Beyond daily behavior, the research reveals that artificial skyglow impacts oyster physiology at an annual scale. The exposure induces a phase advance in body weight and shell length growth. The gametogenetic cycle also experiences a corresponding shift in timing.
These combined chronobiological and physiological effects could ultimately lead to a disruption of the oyster’s fitness within its natural habitat. Long-term field data collected throughout the year in Arcachon Bay substantiate these conclusions, bridging a critical gap in understanding how nocturnal light pollution pressures marine ecosystems.
