JENKS, S. M.*; KHAN, S.; TRACY, K.; KENDALL, K.; The Sage Colleges; The Sage Colleges; The Sage Colleges; The Sage Colleges : Photoperiod influence on crayfish agonistic behavior

Alterations in monoaminergic neurotransmission are thought to underlie photoperiodic variation in mood, aggression and affective disorders in humans. Research by several investigators on crayfish neurobiology has shown a connection between serotonin, aggression and social interaction. We investigated the influence of light exposure on crayfish agonistic behavior. A pilot study suggested that extreme alteration of photoperiod following dominance establishment resulted in status reversals. We extended our investigations by using a less extreme light treatment (20 hours light:4 hours dark versus 4 hours light:20 hours dark exposure for six days) and three conditions: dominants under 20 hours of light retested with their subordinates exposed to 20 hours dark, and the converse, and control pairs (LD 12:12). Although we did not observe a significant number of status reversals, changes in behavior did occur. For both light conditions, there was a significant decrease in submissive behaviors in both dominant and subordinate animals retested with their original partners. Aggressive behavior increased significantly following exposure to the LD 4:20 condition in subordinates. The results suggest that light treatment has the most impact on submissive behavior in general and on aggressive behavior in subordinates. We are currently examining how social experience and light treatment interact to modulate crayfish agonistic behavior.