Behavioral responses of two sympatric species Armadillo officinalis and Chaetophiloscia elongata (Crustacea, Oniscidae) towards zinc contaminated litter

ABSTRACT

This study deals with the impact of zinc on the locomotor activity rhythm of two terrestrial isopods Armadillo officinalis and Chetophiloscia elongata. Specimens are collected from the banks of Ghar El Melh lagoon. The locomotor rhythm of untreated and treated individuals with zinc is studied in the laboratory under constant darkness for 10 days. Results showed that untreated individuals of A. officinalis and C. elongata exhibited nocturnal behavior. After Zn exposure, these species concentrated their locomotor activities more or less in the subjective day. Whatever the species, the locomotor patterns became in majority multimodal for treated individuals. We noted, in addition, the absence of the unimodal profile. Through periodogram analysis, ultradian and circadian components were determined whatever the experimental conditions. The most important rhythmicity was determined in the control individual of A. officinalis (73.7%) as well as of C. elongata (52.6%). Furthermore, the locomotor behavior is less stable for contaminated individuals of the two sympatric species. Moreover, contrary to C. elongata, A. officinalis individuals became significantly more active after their exposure to zinc contaminated litter (α_DD+Zn = 5h03 ± 2h33).

KEYWORDS:

• Terrestrial isopods
• locomotor behavior
• circadian components
• constant darkness
• metallic trace element

Disclosure statement

No potential conflict of interest was reported by the authors.