Effects of aperiodic and photoperiodic regimens on the locomotor activity rhythm of the terrestrial isopod Tylos europaeus (Arcangeli, 1938) from Barkoukech Beach (Tabarka, Tunisia)

ABSTRACT

The locomotor activity of the supralittoral Oniscïdea species, Tylos europaeus collected from Barkoukech Beach was monitored in individual animals under natural light/dark cycle, constant darkness and continuous light. Actograms and mean activity curves showed that this species concentrated its activity during the experimental and subjective night whatever the regimen. This nocturnal rhythm was controlled by ultradian and circadian components mostly close to 12 h and 24 h with the nLD cycle and lengthened under aperiodic regimens. Globally, the number of active animals, the stability of the rhythm and the mean activity time were lowest under continuous light suggesting that this regimen could be as a stress condition for the locomotor behaviour of Tylos europaeus.

KEYWORDS:

• Barkoukech Beach
• Tylos europaeus
• light/dark
• constant darkness
• continuous light

Disclosure statement

No potential conflict of interest was reported by the authors.