What conditions other than high phytoplankton production might be indicated by high dissolved oxygen contents?
The upper panel displays the Delta Outflow Index for 1993-1995. The lower panel shows the changing distribution of dissolved oxygen at the Bay surface along the USGS sampling transect. Color is proportional to oxygen content, with lighter (yellow) shadings indicating oxygen supersaturation (high values) and darker (brown) shadings indicating under saturation (low values). The vertical axis represents variability in space from the Sacramento River (top of image), to the Central Bay, and then to the lower South Bay (bottom of image). The horizontal axis represents change over time from 1993 through 1995. Description of Circled Numbers: 1. During periods of high Delta outflow, such as in early 1993, the oxygen content of the water becomes reduced because bacteria, plants, and animals consume oxygen faster than it can be replenished by phytoplankton photosynthesis or exchanges with the atmosphere. 2. The oxygen content of Bay waters is an indicator of the metabolic activity of all the orga
