41.1 Thursday, Jan. 5 Wild but not angry – mangrove rivulus Kryptolebias marmoratus captured from crab burrows in the field show little sign of aggression CURRIE, Suzanne*; FULLER, Adam; EARLEY, Ryan L; COOPER, Chris; REAGAN, Kelly; TAYLOR, D Scott; WRIGHT, Pat A; Mount Allison University, Sackville, NB; University of Alabama, Tuscaloosa; University of Alabama, Tuscaloosa; University of Guelph, Guelph, ON; University of Guelph, Guelph, ON; Brevard County Environmentally Endangered Lands Program, Melbourne, FL; University of Guelph, Guelph, ON firstname.lastname@example.org
The hermaphroditic mangrove rivulus Kryptolebias marmoratus reared in the lab in isolation have been used as a model species to understand combat behaviour and contest outcome in teleost fish. Anecdotal information in the literature suggests that K. marmoratus leave water (emerse) in response to aggressive social encounters. With this in mind, we tested the hypothesis that wild fish would form social hierarchies and “losers” would escape by emersing more often than “winners”. Our results demonstrated that wild fish engaged in few aggressive encounters, whether in natural crab burrows or placed in dyads or triads in aquaria. This passive behaviour was not correlated with testosterone levels, as there were no significant differences between testes testosterone concentrations in wild fish in behavioural trials relative to lab-reared or wild control fish. Social interaction did not increase the number of emersion attempts. In fact, post-interaction emersion rates were ~60% lower relative to pre-interaction rates. In follow-up experiments on lab-reared fish we tested the hypothesis that social isolation under laboratory conditions alters behaviour. Group-reared fish habituated to an intruder stimulus, whereas fish reared in isolation remained aggressive. Taken together, these findings reveal that wild fish are not strongly aggressive which may relate, in part, to early social interactions with conspecifics in crab burrows.