Abstract


IMPACTS OF THE 2014 SEVERE DROUGHT ON MICROCYSTIS BLOOMS IN SAN FRANCISCO ESTUARY

A severe drought in 2014 provided the opportunity to test the hypothesis that the magnitude, toxicity and duration of the freshwater cyanobacterium, Microcystis, will increase with drought conditions in San Francisco Estuary. The 2014 drought, the third driest year on record, was characterized by a 66% to 85% reduction in riverine streamflow into the estuary. The 2014 Microcystis bloom had the highest biomass and toxin concentration and the longest duration on record. Chlorophyll concentration increased by 13 and 9 fold over previous wet and dry years, respectively. Similarly, total microcystins toxin concentration exceeded that in previous wet and dry years by a factor of 69 and 11, respectively. Persistence of warm water temperature in the fall and early initiation of warm water temperature in the spring extended the bloom four months longer than previous blooms. The bloom was also associated with extreme nutrient concentration, including a 20 year high in soluble reactive phosphorus and low in ammonium concentration. Isotope analysis indicated the bloom used ammonium as its primary nitrogen source. Genetic analysis indicated cyanobacteria dominated the primary producer community, increased in diversity over previous years, and was accompanied by a suite of other bacteria.

Authors

Lehman, P. W., California Department of Water Resources, USA, Peggy.Lehman@water.ca.gov

Kurobe, T., University of California at Davis, USA, tkurobe@ucdavis.edu

Lesmeister, S., California Department of Water Resources, USA, Sarah.Lesmeister@water.ca.gov

Mizel, M., University of California at Davis, USA, mtmizel@ucdavis.edu

Baxa, D., University of California at Davis, dvbaxa@ucdavis.edu

Teh, S. J., University of California at Davis, USA, sjteh@ucdavis.edu

Details

Oral presentation

Session #:SS04
Date: 06/06/2016
Time: 10:15
Location: Sweeney Ballroom B

Presentation is given by student: No