Floodplain production

Posted on May 26, 2009

Although floodplain habitats are recognized as areas of high river productivity, there have been few direct comparisons of production in the floodplain and the main channel.  In the first half of the calendar year, discharge to the Sacramento Riveris high because of rainfall and snowmelt, and water is diverted through the Yolo Bypass, a 240 km2 floodplain.  Simultaneous monitoring in the main channel and the bypass revealed that although the floodplain received only 3% of the total stream flow, it contributed 14-37% of the total algal biomass entering the estuary downstream.  These findings support the idea that if river water can be passed through a floodplain during the flood season, inputs to aquatic food webs should increase.

An interesting finding in this study was that, while algal production was positively related to light and temperature in winter and early spring, these relationships were negative in late spring and summer – presumably because intense light levels near the surface had an inhibitory effect on algal growth.

Reference: Lehman P.W., & Sommer, T. & Rivard, L.  2008.  The influence of floodplain habitat on the quantity and quality of riverine phytoplankton carbon produced during the flood season in San Francisco Estuary.  Aquatic Ecology 42,363–378.