Findlay, S. Institute of Ecosystem Studies, FindlayS@ecostudies.org
Quinn, J. National Institute of Water and Atmosphere, j.quinn@niwa.cri.nz
Hickey, C. National Instisute of Water and Atmosphere, c.hickey@niwa.cri.nz
Burrell, G. University of Canterbury, g.burrell@zool.canterbury.ac.nz
Byrnes, C. Beloit College, BYRNESC@STU.BELOIT.EDU

 
"ALL CAUGHT UP IN SUNLIGHT," PHOTOLYSIS RELATIVE TO OTHER SOURCES AND SINKS OF STREAMWATER DOM
 
Streamwater dissolved organic matter is derived from multiple sources and can be removed by a variety of processes. We examined DOM moving along riparian and hyporheic flowpaths and quantified photolytic effects on DOM composition and ability to support bacterial growth. A set of streams and riparian wetlands in New Zealand and several sites within the East Branch of the Wappinger Creek in New York were sampled to describe flowpath-induced differences in DOM. Photolysis experiments were conducted to contrast photolytic effects with differences due to flowpath. Near-stream flowpaths generally showed higher quantities of DOM but did not consistently yield higher growth rates. Exposure to sunlight resulted in two-fold increases in growth rates for one of the two New Zealand streams but caused declines in growth for one of the New York sites. Both the type of flowpath and light exposure resulted in dramatic shifts in DOM composition as evidenced by shifts in activities of extracellular enzymes. Light exposure decreased rates of b-glucosidase, peptidase and esterase for samples from the New York sites. Photolytic effects on stream DOM are occasionally significant but their net effects are more variable than the stimulation of DOM bioavailability commonly reported for lentic systems.
 
Day: Thursday, Feb. 4
Time: 04:30 - 04:45pm
Location: Sweeney Center
 
Code: SS33TH0430S