For the past couple of years, Santa Barbara Channelkeeper has been studying the effects of algae on water quality within the Ventura River watershed. The general issue is outlined here - the main point being that dissolved oxygen drops to a minimum after a long night when algae and aquatic plants are not photosynthesizing...
Which is why we get up (way too early) to sample our monitoring sites before the sun comes up. This video illustrates how we do this in the dark:
Channelkeeper's Stream Team data is being utilized to develop a TMDL (Total Maximum Daily Load) program to address the 303(d) algae impairment listing for the Ventura River. Working in collaboration with UCSB researchers, Channelkeeper has produced a number of reports, which may be downloaded from their website here.
If you'd like to get involved please contact Ben at email@example.com