Dr Peggy Lehman, DWR and Jerrica Lewis of the Stockton Fish and Wildlife Office prepare a plankton net for Microcystis sampling. (photo: USFWS)

by Ken Behen and Casey Smith, Stockton FWO

During summer 2008, several members of the Stockton Fish and Wildlife Office's Delta Juvenile Fish Monitoring Program assisted Dr. Peggy Lehman of the California Department of Water Resources and graduate students from the University of California-Davis with sampling and collection of the cyanobacteria Microcystis aeruginosa throughout the Sacramento-San Joaquin Delta. Microcystis  aeruginosa occurs naturally in low abundances in surface waters.  However, with warm water temperatures and high nutrient availability, M. aeruginosa grows at increased rates.  At high abundances, M. aeruginosa produces large amounts of a harmful toxin known as microcystin. Toxic algae blooms have been assumed to negatively affect water quality as well as systemic organisms. 

Sampling was conducted from the western portion of the Delta southward, focusing on areas with historically abundant blooms. Sampling methods consisted of zooplankton and algae trawling.  Ultraviolet light penetration and water quality were measured at sampling locations.  Future sampling efforts will increase our understanding of the effects of toxic algae blooms on systemic organisms and aid in informed policy and regulatory decisions. 

The data from this study was presented by Dr. Lehman at the 2008 CALFED Science Conference.