Meeting Abstract
P1.96 Sunday, Jan. 4 Fiddler crab locomotion: Are tide-related rhythms the same in lab and field studies? BIER, R*; TANKERSLEY, R; LOPEZ, P; BRODIE, R; University of Georgia; Florida Institute of Technology; Scripps Institute of Oceanography; Mount Holyoke College raven.bier@gmail.com
Some behaviors of intertidal organisms are endogenously regulated and correlate with the cycle of ebbing and flooding tides. For organisms that feed intertidally, timing their movement to and from feeding areas may be especially important if they are to take advantage of favorable feeding conditions. Fiddler crabs ( Uca ) feed on exposed substrates at low tide and are a model organism for biological rhythms research. The purpose of this study was to determine if drove migration by the fiddler crab Uca pugilator between feeding and burrow locations under the natural conditions of its habitat was correlated with circadian or tidal rhythms. For 15 days in July 2005, during sunlight hours, we recorded the number, direction (toward feeding area = outbound or away from feeding area = inbound), and sex of crabs at an observation point between the burrow and feeding areas on a mud flat. Additionally, we collected 20 U. pugilator from the field site and recorded their locomotory movement for 7 days under controlled conditions using an infra-red actograph system. A general linear model showed that the time of high tide corresponded with both outbound and inbound movement in the field, but that the peak time of movement in the field did not correspond with peak frequency of movement under controlled conditions. There was no significant sex difference in the timing of this movement in the field, though under controlled conditions females’ peak activity occurred 1 hour prior to males’. Thus, peak inbound or outbound movement for a U. pugilator drove at the field site can be used to predict the time at which a flooding or ebbing tide may occur there. Moreover, this study highlights the importance of observing activity in the field, as the results under controlled conditions did not reveal the functional locomotory pattern.
