Artificial Light at Night (ALAN) alters the behavior and physiology of a sandy beach isopod. Are these effects reversible?

Artificial Light at Night (ALAN) is becoming a pervasive stressor in both terrestrial and marine habitats, posing a threat to species whose behavior and physiology rely on natural light/dark cycles. While numerous studies have examined the biological impacts of ALAN, far fewer have investigated the ability of organisms to recover from this stressor. This study used the sandy beach isopod Tylos spinulosus as a model species to assess the short-term effects of ALAN and its potential recovery following the removal of light sources. To achieve this, we conducted separate laboratory experiments to evaluate changes in locomotor activity, food consumption, food absorption efficiency, and growth rates under ALAN exposure and during recovery. We defined recovery as the state in which the measured responses statistically returned to control levels after deviating from those recorded for the same individuals under ALAN conditions. The results showed that ALAN had a detrimental effect on all four variables. While food consumption and growth returned to control levels after ALAN removal, activity and absorption efficiency did not, indicating a lack of recovery within the timeframe of the trials. These results suggest that the recovery of this species from short-term light pollution exposure is heavily dependent on the behavioral or physiological responses under examination. Hence, a broader range of responses over longer-term experiments are suggested to better understand the ability of this species to recover from light pollution at time scales relevant to management.