Research Areas > Regional Monitoring > Bight Regional Monitoring > Offshore Water Quality > Bight '08 Water Quality

Project: Bight '08 Water Quality

Background and Objectives

The environmental factors associated with harmful algal bloom toxin production are not well understood. The results of the Bight '03 Regional Monitoring Program established that Pseudo-nitzschia, a diatom that produces the neurotoxin domoic acid, was found to occur in high numbers in Los Angeles Harbor, but that its occurrence in other parts of the Southern California Bight (SCB) was not well documented. Pseudo-nitzschia abundances and toxin concentrations were associated with decreases in macronutrient concentrations (phosphate and silicate) as well as with changes in nutrient ratios. However, the sources of these nutrients were not conclusively determined.

SCCWRP routinely quantifies anthropogenic contributions of metals and organics to the coastal ocean, based largely on collated data from the many discharge monitoring programs that are required by NPDES permits. Nutrients present a greater challenge, though, because many nutrient species are not measured in routine monitoring programs. In addition, anthropogenic contributions of nutrients need to be separated from natural nutrient sources such as ocean upwelling.

To fill these information gaps, the Bight '08 offshore water quality study has three major objectives:

1) Establish the relative nutrient contributions of four major sources to the SCB (upwelling, POTW discharge, atmospheric deposition, terrestrial coastal runoff)

2) Characterize the spatial and temporal patterns of algal blooms, as well as the effects of these blooms, with an emphasis on HAB species (e.g., Pseudo-nitzschia) and toxin (e.g., domoic acid) identification

3) Characterize the specific water quality conditions and nutrient sources associated with bloom events

Status

This project was initiated in 2008 with anticipated completion in 2012.

Methods

Researchers working on the Bight '08 Water Quality project will engage in following tasks to address the three major objectives:

1) Nutrient loads from upwelling will be estimated by combining ship-based discrete samples with the Regional Ocean Model System (ROMS) physical circulation model. Nutrient loads from POTW discharge will be measured directly through analyses of monthly effluent samples and measured discharge rates from the four largest (plus several smaller) POTWs in southern California. Nutrient loads from terrestrial runoff will be estimated using models based on data from several mass emission stations located at the discharge points from Bight coastal watersheds. Atmospheric deposition of nitrogen and phosphorus will be measured as wet and dry deposition at stations in several locations both onshore and offshore.

2) The spatial and temporal patterns of algal blooms and, in particular, the occurrence of Pseudo-nitzschia and domoic acid will be monitored. First, historic patterns in algal bloom frequency and biomass will be assessed by remote sensing. The temporal and spatial occurrence of Pseudo-nitzschia and associated concentrations of domoic acid, nutrient and other physiochemical parameters will also be monitored with a combination of gliders, pier-based and ship-based sampling from January to June 2010. Triggers for sampling will be tracked in partnership with the Southern California Coastal Ocean Observing System (SCCOOS).

3) To investigate factors associated with bloom events, data will be collected on ambient nutrient concentrations and loads from the various sources, upwelling patterns, and other remote sensing data. Natural isotope ratios found for the four major sources of nutrients will be used as tracers to identify their relative contributions to ambient surface waters during bloom events.
 

Partners

This project is being conducted in close cooperation with all of SCCWRP’s member agencies and other Bight '08 participants. In total, over 60 different organizations including regulated, regulatory, and non-governmental agencies are expected to collaborate on this project.

Presentation

• Modeling terrestrial nutrient emissions in wet and dry runoff (Video)- January 2011 presentation to SCCWRP member agencies describing the modeling approach for quantifying nutrient inputs to the Bight from terrestrial runoff.

Poster

• NP Nezlin. 2009. Satellite tracking of harmful algal blooms. Presented at 2nd Annual SCCWRP Symposium.