Resolving the annual pattern of algal toxins in coastal waters off Los Angeles

Astrid Schnetzer, North Carolina State University
David Caron, University of Southern California

Southern California waters are impacted by recurring harmful algal blooms (HABs). These blooms can disrupt the food chain, cause low-oxygen conditions that lead to fish kills in embayments and harbors, and create a threat to animal and human health. The most toxic algae that are commonly observed in Southern California waters are diatoms within the genus Pseudo-nitzschia and dinoflagellates within the genus Alexandrium. Members of both genera are capable of producing potent neurotoxins that can be transferred through the food chain. Domoic acid (DA), the toxin produced by Pseudo-nitzschia, has been implicated in bird and mammal strandings and/or deaths of several hundreds of animals in recent years. Our previous research has demonstrated that the region surrounding the port of Los Angeles may be a 'hotspot' for Pseudo-nitzschia and DA toxicity events. Very recently we confirmed the presence of Alexandrium and saxitoxins (STX) south and north of the LA harbor at Newport Pier and in Redondo Beach Harbor, but at this time, we do not know the extent of these phenomena in these environments or in the Port of Los Angeles.

Understanding the spatiotemporal dynamics of HAB species requires sensitive methods that can characterize toxic events from bloom initiation to demise. Determining abundances of toxic algae traditionally requires detailed microscopy to identify and enumerate cells and considerable taxonomic expertise. This limits the number of samples that can be processed. Additionally, simple toxin detection methods, especially those that facilitate in situ monitoring, are only now becoming routinely available. We propose to document abundance dynamics for the most toxic Southern California HAB species (Pseudo-nitzschia and Alexandrium) inside the Los Angeles Harbor, at Newport Pier, in Redondo Beach Harbor and at Wrigley Pier on Catalina Island. This task will be accomplished by employing species-specific state-of–the-art molecular approaches for identification and enumeration in concert with newly-developed toxin detection methods including a protocol for continued tracking of phycotoxins in situ. Finally, the PIs will employ the same molecular approaches to analyze archived samples to test for differences in the frequency and duration of DA and/or STX toxicity events inside the Los Angeles Harbor compared to the adjacent San Pedro Channel.