Research Areas > Nutrients > Harmful Algal Blooms (HABs) > Assessment of Pseudo-nitszchia and Domoic Acid on the San Pedro Shelf

Project: Assessment of Pseudo-nitzschia and Domoic Acid on the San Pedro Shelf

Background and Objective

The most frequently observed Harmful Algal Bloom (HAB) in southern California is Pseudo-nitzschia, a diatom that produces the neurotoxin domoic acid. The two most recent blooms of this species, in 2006 and 2007, produced domoic acid concentrations that were among the highest ever reported in natural populations along the US west coast. However, the preceding environmental conditions that lead to Pseudo-nitzschia blooms and toxin production in southern California are not well understood.

The objective of this project is to build upon findings from Bight’03 by providing more comprehensive spatial and temporal coverage of Pseudo-nitzschia and domoic acid densities. This objective will be reached through the implementation of a HAB monitoring program that incorporates: 1) innovative in situ sensor networking technology 2) cutting-edge species identification and domoic acid quantification methods, and 3) state-of-the-art remote sensing. The project will also investigate correlations between environmental concentrations of domoic acid and concentrations of the neurotoxin in stranded marine animals.

Status

This is an ongoing project with anticipated completion in 2011.

Methods

Sampling will take place on a periodic basis at a small set of sites in coordination with the quarterly regional water quality survey conducted by SCCWRP member agencies. High concentrations detected during this regular sampling will be followed up by more comprehensive spatial sampling. As the program matures, an automated in situ sensor network will be installed to serve as this trigger. Researchers will also investigate correlations between the observed environmental concentrations of domoic acid and concentrations of the neurotoxin in stranded marine animals.

Findings

Preliminary findings from this project have increased knowledge of the spatial and temporal dynamics of algal blooms, the concentrations of domoic acid in phytoplankton and higher organisms, and the identity of Pseudo-nitzschia species that are the likely toxin-producers within specific geographical regions. The highest recorded concentrations of domoic acid in natural seawater assemblages were found from April to May 2007 in coastal waters off the Los Angeles-Long Beach harbor. These exceptionally high concentrations of toxin resulted in greatly elevated stranding and mortality rates for marine mammals and seabirds. In summary, results from this and past SCCWRP studies have indicated that toxic blooms of Pseudo-nitzschia are a recurring phenomenon of major concern in southern California coastal waters.

Partners

This project is being conducted in collaboration with researchers from the University of Southern California, University of California, Los Angeles and University of California, Santa Cruz.