MacIntyre, H. L.. University of Maryland Horn Point Laboratory, macintyr@hpl.umces.edu
Chiscano, C. L.. University of Maryland Horn Point Laboratory, chiscano@hpl.umces.edu
Koch, E. W.. University of Maryland Horn Point Laboratory, koch@hpl.umces.edu
Vecchio, J. , vecchio@hotmail.com

 
PARTITIONING OF PRIMARY PRODUCTION BETWEEN THE WATER COLUMN AND BENTHOS IN THE CHOPTANK RIVER (MD, USA), A SHALLOW-WATER ESTUARINE ENVIRONMENT
 
Primary production by suspended and benthic microalgae in a shallow (1 m) water column was derived from spectrally-resolved estimates of light attenuation and the photosynthetic responses of the two populations. Samples were collected hourly during 14 days of relatively low wind stress and 3 days of high winds associated with Hurricane Bonnie. The chlorophyll content of the upper 2 mm sediment was on average 3 x that of the overlying water, and the benthic and suspended microalgae had comparable photosynthetic characteristics. Even so, the benthos accounted for only 10 - 60% of total productivity. Water column and benthic productivity varied with the magnitude and spectral dependence of light attenuation, both of which were modulated largely by absorption by resuspended detritus. Experiments under controlled conditions showed that less than 2% of the chlorophyll in the upper mm of sediment was resuspended under moderate friction velocities (<1 cm/s) and confirmed that detrital resuspension was inversely related to the chlorophyll content of the sediment. These relationships allow the possibility of a positive feedback between benthic population density and light penetration through the water column. A secondary effect on photosynthesis by suspended microalgae may drive partitioning of productivity between the water column and benthos.
 
Day: Monday, Feb. 1
Time: 02:00 - 02:15pm
Location: Sweeney Center
 
Code: SS45MO0200S