Squires, M. M. Simon Fraser University - Department of Geography, msquires@sfu.ca
Lesack, L. F W. Simon Fraser University - Departments of Geography and Biological Sciences, Lance_Lesack@sfu.ca

 
RELATIVE CONTRIBUTIONS OF DOC, SESTONIC CHLOROPHYLL, AND SUSPENDED SEDIMENTS TO LIGHT (PAR) ATTENUATION IN LAKES OF THE MACKENZIE DELTA
 
The Mackenzie Delta is a complex environment containing 25,000 lakes. The frequency and duration of river flooding is thought to exert considerable control over the abundance and distribution of phytoplankton, epipelon, macrophytes, and epiphytes among the lakes via the direct effect of riverine suspended sediments on light attenuation. Less clear is how DOC, from internal and external sources, and sestonic chlorophyll affect light availability and in turn autotroph assemblages. We followed light attenuation and concentrations of suspended sediments, DOC, and sestonic chlorophyll over the open-water period for a subset of delta lakes exhibiting a clear gradient in flood frequency. Preliminary analysis confirms a dominant influence of suspended sediments, particularly in frequently flooded lakes, but also shows a substantial effect of DOC and chlorophyll in many of the lakes. The effect of DOC and sestonic chlorophyll may be strongest in lakes where the flood frequency and suspended sediments are at intermediate levels rather than in very clear or very turbid lakes. Understanding the controls on the light environment among lakes of the Mackenzie Delta is necessary if we are to predict the responses of the autotroph communities to the multiple stresses of global change.
 
Day: Monday, Feb. 1
Time: 02:30 - 02:45pm
Location: Hilton of Santa Fe
 
Code: SS47MO0230H