Porter, E. T. University of Maryland, CES, elka@hpl.umces.edu
Sanford, L. P. University of Maryland, CES, lsanford@hpl.umces.edu
Crawford, S. M. University of Maryland, CES, crawford@hpl.umces.edu
Gust, G. Technical University Hamburg-Harburg, gust @tu-harburg.de
Porter, F. NASA/Goddard Space Flight Center, porter@milkyway.gsfc.nasa.com

 
SCALING WATER COLUMN MIXING AND BOUNDARY-LAYER FLOW IN STUDIES OF BENTHIC-PELAGIC COUPLING
 
In shallow aquatic environments, benthic and pelagic processes affect each other through direct and indirect pathways. Mixing and flow in the water column and at the benthos can alter these interactions. When controllable field studies are impractical, experimental ecosystems provide an alternative for studying these processes, although it is difficult to reproduce both benthic and water column flow accurately. We developed two scaled experimental ecosystems to simulate both realistic water column mixing and benthic boundary-layer flow. One system coupled a medium-sized mesocosm with an annular flume, the second a small mesocosm with a Gust microcosm. We compared benthic shear stress, flow speeds and internal mixing energies in the coupled systems to standard single tank mesocosms with the same sizes and shapes. In addition, we performed experiments with sediments and bivalves in all systems. Benthic shear velocities were unrealistically low in the single tanks but were much more reasonable in the coupled systems, relative to internal water column mixing energy. Low shear velocity at the benthos in typical single tank mesocosms may affect mass transfers, particle deposition and transport, organism behavior, resuspension, nutrient transformations and regeneration, and contaminant transport. Indirect interactions and nutrient transformations were most affected in our bivalve experiments.
 
Day: Wednesday, Feb. 3
Time: 09:00 - 09:15am
Location: Eldorado Hotel
 
Code: SS03WE0900E