Scientists Launch Two-Pronged Approach to Map Cyanotoxins in Bay-Delta

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Over the last few decades the Sacramento-San Joaquin River Delta has experienced declines in phytoplankton productivity and a shift in species composition resulting in observed increases in harmful algal blooms (HABs).

Flakes of microcystis floating in the water of the southern Delta

This photo shows flakes of microcystis, a genus of freshwater cyanobacteria, floating in the water of the southern Delta.  (Click to enlarge.)

While some HABs are nontoxic, others contain cyanobacteria (also referred to as blue-green algae) which may produce dangerous toxins (cyanotoxins) that pose a health threat to people and animals. These cyanotoxins also may be an additional stressor on declining native fish populations and other organisms living in the Delta’s aquatic ecosystem.

To monitor cyanotoxins in the Delta, USGS scientists will use a two-pronged approach: (1) collection of cyanotoxin data at fixed high frequency water quality monitoring stations, and (2) collection of cyanotoxin data across broad spatial domains during USGS high-resolution, boat-based mapping surveys. For both efforts, USGS scientists will collect discrete whole water samples and also will deploy Solid Phase Adsorption Toxin Tracking (SPATT) samplers.  The SPATT samplers are able to pick up cyanotoxins present in large volumes of water, thus allowing collection of cyanotoxin data integrated over time and/or space. 

This research will contribute to USGS efforts to develop HAB and cyanotoxin monitoring approaches and to initiate a much-needed HAB and cyanotoxin monitoring program for the Delta. In addition, the boat-based approach will serve as a proof-of-concept for a new and novel method for collecting highly resolved spatial water quality data alongside cyanotoxin concentration measurements that may be applied virtually anywhere that cyanotoxin HABs occur.

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