Grantee Research Project Results
2005 Progress Report: Stimulation of Toxic Blooms of the Diatom Pseudo-nitzschia spp. by Urban River Discharge into Southern California Coastal Waters
EPA Grant Number: R831705Title: Stimulation of Toxic Blooms of the Diatom Pseudo-nitzschia spp. by Urban River Discharge into Southern California Coastal Waters
Investigators: Caron, David A. , Miller, Peter E. , Schnetzer, Astrid
Institution: University of Southern California , University of California - Santa Cruz
EPA Project Officer: Packard, Benjamin H
Project Period: September 1, 2004 through August 31, 2007 (Extended to August 31, 2008)
Project Period Covered by this Report: September 1, 2004 through August 31, 2005
Project Amount: $350,765
RFA: Ecology and Oceanography of Harmful Algal Blooms (2004) RFA Text | Recipients Lists
Research Category: Aquatic Ecosystems , Water
Objective:
The Los Angeles area of the Southern California Bight is the focal point of this field-oriented Ecology and Oceanography of Harmful Algal Blooms research program to investigate the relationship between freshwater inputs from a highly urbanized coastal region and blooms of the toxic diatom Pseudo-nitzschia. The Los Angeles Harbor and adjacent coastal ocean is periodically influenced by runoff from three major rivers. Freshwater discharge from the Los Angeles River, San Gabriel River, and Santa Ana River contribute substantial amounts of inorganic nutrients, labile organic compounds, and trace metals to the coastal region. River input is strongly episodic, highly channelized, and restricted primarily to winter/early spring. It is hypothesized that these meteorological events greatly influence phytoplankton dynamics and the formation of harmful algal blooms. This research program examines the connection between storm events and Pseudo-nitzschia species success and the production of domoic acid (DA) in coastal communities.
Figure 1. Study Region. Surface water sampling was conducted at 20 stations. Conductivity-temperature depth profiler casts were completed at five of these stations and additional samples obtained at the subsurface chlorophyll maximum (yellow dots).
Progress Summary:
Multiple surveys (weekly to monthly) were conducted throughout 2005 to examine the spatial and temporal relationship between river discharge, Pseudo-nitzschia abundance, DA production, and pertinent chemical/physical (temperature, PO4, NO3+NO2, Si(OH)4) parameters. The study area encompassed approximately 400 km2 of the coastal Southern California Bight between the Palos Verdes peninsula and Newport Beach (Figure 1). More frequent sampling (weekly to bimonthly) typically followed after strong rainfall events.
Several phytoplankton blooms were documented during the project’s first field season (total chlorophyll shown in Figure 2). A mixed diatom bloom in mid-April was dominated by Chaetoceros spp., and Pseudo-nitzschia spp. was abundant. DA at that time was detected throughout most of the study area (mean = 1.2 μg DA per liter). Known toxin-producing species were identified as P. delicatissima, P. fraudulenta, and P. pungens using scanning and transmission electron microscopy. A bloom that was solely dominated by P. delicatissima was observed inside the inner breakwater of the Los Angeles harbor at the beginning of July. Although cell abundances reached 6 x 106 cells per liter, particulate DA during this highly localized event did not exceed 0.01 μg per liter. Pseudo-nitzschia spp. was also present outside the Los Angeles harbor but was outnumbered by diatoms Asterionella spp. and Chaetoceros.2005 was also characterized by a series of dinoflagellate-dominated blooms, which typically occurred in immediate proximity to the coast (e.g., during mid-May, end of May, June, August, and September; Figure 2).
Data Processing and Analysis
Physical, chemical, and biological parameters were measured for each of the sampling stations and dates to investigate the relationship between inorganic nutrients (PO4, NO3+NO2, Si(OH)4), temperature and chlorophyll with Pseudo-nitzschia abundances and DA concentrations (particulate and cellular DA). These analyses will provide insight into the existent environmental conditions during the observed Pseudo-nitzschia events (nontoxic and toxic) and their temporal and spatial relationship to episodic river discharge into the Los Angeles harbor and the adjacent San Pedro Shelf region. Enumeration and identification of Pseudo-nitzschia is currently based on light and electron microscopical analyses, however, a major component of this project is the development of quantitative PCR (qPCR) protocols to identify and quantify different species of Pseudo-nitzschia in near real time.
Figure 2. Surface Chlorophyll Distribution During Field Surveys From March Through December 2005. Surface water sampling was conducted at 20 stations.
Future Activities:
The investigators did not report any future activities.
Journal Articles:
No journal articles submitted with this report: View all 41 publications for this projectSupplemental Keywords:
marine, southwestern coastal ocean, toxicity, domoic acid, plankton, phytoplankton, Pseudo-nitzschia, ecosystem damage, environmental biology, ecology, remote sensing, satellite, immunology, molecular biology, microscopy,, RFA, Ecosystem Protection/Environmental Exposure & Risk, Scientific Discipline, Geographic Area, Water, algal blooms, Ecological Risk Assessment, State, Aquatic Ecosystem Restoration, estuarine research, Oceanography, Wet Weather Flows, Ecology and Ecosystems, Environmental Monitoring, California (CA), environmental indicators, river discharge, restoration strategies, environmental restoration, contaminated waterfronts, estuaries, risk assessment, combined sewer overflows, aquatic ecosystem, storm events, monitoring, domoic acid producing diatoms, real-time monitoring, storm drainage, environmental stress, bloom dynamics, aquatic degradation, precipitation monitoring, wetlands, storm water, algal bloom detection, groundwater pollution, stormwater runoff, conservation, watershedProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.