At UCLA

12 de abril de 2019

Within the California Current System (CCS), the toxigenic

harmful algal diatom genus Pseudo-nitzschia (PN), and its potent neurotoxin domoic acid (DA), are

now considered to be the leading HAB and conservation issues for much of the U.S. West Coast, as

these events have the potential to be devastating to aquatic life and harmful to human health. The connection between HABs and anthropogenic nutrient enrichment, coastal processes (e.g. upwelling), and climate forcing at the land-sea interface are critical lines of investigation, yet the relative importance of these drivers has not been systematically evaluated. However, such an evaluation is key to a cost-effective strategy to manage water quality coastal resources at local scales. Development of the pre-operational application system California Harmful Algae Risk Mapping (C-HARM) for the Southern CCS predicts toxin and PN blooms as a function of statistical relationships with temperature, salinity, and optical variables. The absence of near real-time nutrient measurements hinders the ability to include nutrient variables in this modeling system, and thus a good deal of information relevant to bloom formation and DA production is ignored. In order to establish a state-of-the-art system built on the first principles of PN physiology, this proposed project intends to build a modeling system in parallel with C-HARM that leverages previous studies on the nutrient response by PN populations.

1) develop an end-to-end predictive capacity for DA

production in the southern CCS (Baja Mexico to California-Oregon Border) that: a) builds upon

previous development of a mechanistic model of DA production parameterized from laboratory

experiments with toxigenic PN, b) adapts a state-of-art Nutrient-Phytoplankton-Zooplankton

(NPZ) model construct to explicitly represent PN biomass and DA production, c) is coupled to a

realistic regional physical-biogeochemical model, and d) can be evaluated against observational

data; 2) use the integrated model to investigate the relative importance of anthropogenic inputs

and temperature on the frequency and severity of PN blooms and associated DA events in the

Southern CCS; and 3) transmit these findings to coastal zone managers and help them explore

their implications for marine resource management and pollution control.