D'Andrea, A. F. Marine Sciences Research Center, adandrea@ic.sunysb.edu
Aller, R. C. Marine Sciences Research Center, raller@ccmail.sunysb.edu
Lopez, G. R. Marine Sciences Research Center, glopez@notes.cc.sunysb.edu

 
RAPID FLUX AND TURNOVER OF REACTIVE POREWATER CONSTITUENTS ON AN INTERTIDAL SANDFLAT: THE INTERACTION OF PHYSICAL ADVECTION AND MACROBIOLOGICAL PROCESSES
 
Traditional 1-dimensional models of porewater diffusion common for muddy systems are complicated in permeable intertidal sands by tidally-induced porewater advection. Physical advective processes increase the supply and remineralization of OM, remove metabolic products, and result in the rapid flux and turnover of reactive porewater constituents. Macrobiological activities on intertidal sandflats also strongly influence transport-reaction processes. Along the coast of South Carolina, burrowing and feeding by the thallassinid shrimp Callianassa major and the formation of dasyatid ray pits increase the flux of nutrients and OM in particular sediment zones, and can slow or clog porewater advection by the introduction of fine particles. Porewater sippers were utilized to measure real-time porewater profiles on a sandflat in North Inlet, SC, and specifically in the vicinity of C. major burrows and ray pits. Samples were collected from late ebb to early flood tide and analyzed for DO, DIC, DOC, ammonium, nitrate-nitrite, orthophosphate, and total N and P. This sandflat is extraordinarily dynamic. The sediment column is well-oxygenated to ~25cm and completely flushed on timescales of <2 hours. Macrobiological effects are especially evident at slack low tide when physical advection is minimized. There is a significant build-up of DOC (2.38mM/h) and nutrients (e.g. 8uM/h of nitrate-nitrite) around macrobiological structures during this period. Solutes are rapidly flushed out of the sandflat during early flood tidal flow. The interaction of the biological components with the tidally-driven porewater advection plays a significant role in OC supply, decomposition, and preservation in this system.
 
Day: Thursday, Feb. 4
Time: 12:15 - 12:30pm
Location: Hilton of Santa Fe
 
Code: SS30FR1215S