Meeting Abstract
P1.85 Thursday, Jan. 3 Behavioral, Developmental and Physiological Constraints on the Distribution of Fiddler Crabs (Uca minax, Leconte, 1855) Within a River-Dominated Estuary. BORGIANINI, SA*; SUTTON, MC; FLENNIKEN, MM; BRODIE, RJ; University of South Carolina; University of South Carolina Beaufort; Mt. Holyoke College; Mt. Holyoke College borgians@biol.sc.edu
Distribution of juvenile fiddler crabs (Uca spp.) is thought to be determined by physical and biotic stimuli present during the reinvasion of the estuary by megalopae from off-shore environments. The interaction of behavior, development, physiological tolerance and physical factors results in dispersal and eventual settlement of megalopae in various habitats within the estuary. Our laboratory developed and groundtruthed a larval transport model to predict how these processes influence dispersal of Uca minax within the Winyah Bay estuary and its confluent rivers (Georgetown, SC). We focused on the effects of temperature as well as the relationship between putative cues from natural sediment and water from various locations in the river that may affect the timing of metamorphosis and survivorship of megalopae. U. minax megalopae were collected from freshwater reaches of the Waccamaw River, up-estuary from Winyah Bay. Individual megalopa were placed in separate incubation chambers. In the first experiment, water and sediment were changed daily as to mimic the megalopae�s nocturnal saltatorial transit up river based on transport model predictions. In a second experiment, megalopae were incubated at 20�, 25�, 30�C while receiving fresh river water daily. The rate of metamorphosis and survivorship of megalopae were calculated for each experiment and were used to develop a metamorphosis/survivorship function that will be utilized to calibrate our megalopae transport model. Actual on-river distribution of adult U. minax were determined by collecting crabs and conducting burrow counts at multiple sites along the Pee Dee River. Distribution data of adult crabs will be used to groundtruth the transport model for U. minax megalopae.
