HR: 08:45h
AN: NB21E-02    [Abstracts]
TI: High Resolution Monitoring of Algal Growth Dynamics in a Hypereutrophic River in the Central Valley, California
AU: * Henson, S S
EM: sshenson@ucdavis.edu
AF: University of California Davis, Dept. of Land, Air, and Water Resources, Davis, CA 95616 United States
AU: Dahlgren, R
EM: radahlgren@ucdavis.edu
AF: University of California Davis, Dept. of Land, Air, and Water Resources, Davis, CA 95616 United States
AU: Van Nieuwenhuyse, E
EM: evannieuwenhuyse@mp.usbr.gov
AF: U.S. Bureau of Reclamation, 2800 Cottage Way, Sacramento, CA 95825-1898 United States
AU: O'Geen, A T
EM: atogeen@ucdavis.edu
AF: University of California Davis, Dept. of Land, Air, and Water Resources, Davis, CA 95616 United States
AU: Gallo, E L
EM: elgallo@ucdavis.edu
AF: University of California Davis, Dept. of Land, Air, and Water Resources, Davis, CA 95616 United States
AU: Ahearn, D S
EM: dsahearn@ucdavis.edu
AF: University of California Davis, Dept. of Land, Air, and Water Resources, Davis, CA 95616 United States
AB: The lower San Joaquin River in California's Central Valley experiences periods of hypoxia during the late summer and fall that is detrimental to aquatic organisms and migration of fall-run chinook salmon and steelhead trout. Hypoxia is attributable, in part, to excess nutrients from urban waste water and agricultural runoff, which contribute to growth of high concentrations of phytoplankton. This study examined spatial and temporal growth patterns that control algal loading using continuous fluorescence measurements at three sites along a 50 km section of the lower San Joaquin River between April and October. A strong diel fluorescence signal was observed and associated grab samples verified that fluorescence was an accurate measure of chlorophyll. Peak chlorophyll concentrations occurred between 18:00 and 20:00 and minimum concentrations between 10:00 and 12:00. Maximum concentrations were nearly two times greater than minimum concentrations although this ratio varied temporally and spatially. Although the mechanism for the diel chlorophyll signal is not very well understood several parameters including temperature, irradiance, turbidity, residence time, stream depth, and zooplankton grazing were considered within the scope of this study. This study highlights the importance of considering high resolution sampling on algal loading rates within heavily impacted riverine systems.
DE: 1803 Anthropogenic effects
DE: 1871 Surface water quality
DE: 9901 NABS Student Award - Basic Research
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly