DiBacco, C. Scripps Institution of Oceanography, cdibacco@ucsd.edu
Levin, L. Scripps Institution of Oceanography, llevin@ucsd.edu

Many marine benthic invertebrates disperse during a planktonic larval stage of development, however estimating larval exchange between populations has been difficult without a means to determine larval origins. This study employs a newly developed trace-element tracking system to assess exchange rates of crab larvae (Pachygrapsus crassipes) between San Diego Bay (SDB) and exposed coastal populations. Temporal-spatial distributions of newly hatched larvae were examined concurrently with estimates of horizontal and vertical shear (water velocity) to calculate larval flux rates between regions of SDB and the nearshore coastal environment. Larvae were concentrated in surface layers during nighttime ebb and at the sediment water interface during flood conditions, thus facilitating their export from the bay. First order larval flux approximations between inner and outer regions of SDB and between the bay and nearshore coastal habitats indicate net flux out of the bay. Trace elements are being used to establish the origin and track the fate of larvae sampled during flux studies. Initial studies have shown that gradients in natural (Sr, Mg) and anthropogenic (Cu, Al) trace element body burdens of individual crab larvae (P. crassipes) reflect ambient concentrations at brood sites. This larval tracking technique is being used to validate and refine initial net flux estimates.
Day: Friday, Feb. 5
Time: 08:30 - 08:45am
Location: Eldorado Hotel
Code: CS57FR0830E