Detection Methods | Remote Sensing

Limited budgetary resources will mean a heavier reliance on technological innovation so that sampling and obtaining timely data can be more efficiently managed.

Detection Methods

Rapid assays to detect DA in shellfish "in the field" or the presence of toxic algae (e.g.) distinguishing the toxic P. multiseries from the nontoxicP. pungens). These impediments could be virtually eliminated if an inexpensive, quick and sensitive "screening" tool for toxin testing that gives a quick yes or no result to the presence of DA was available for use by coastal managers in remote locations. The capacity for field testing of shellfish at or near the harvesting location will allow for more intensive monitoring for the toxin in shellfish, if needed. Significant cost savings would be realized by eliminating the shipping of nontoxic samples for analysis in state laboratories. When toxin is demonstrated to be absent from samples, product will reach consumers in a timely fashion.

Rapid Test for PSP

A new rapid test has been developed by Maurice Lacock and Joanne Jellett that permits testing for the presence of toxins at shellfish harvest areas and provides results in less than one hour (see figure at right). The reliability of this assay is currently being tested onrazor clam samples on a real-time basis as a collaborative effort among the Quileute tribe, the Northwest Fisheries Science Center, and the National Ocean Service (MERHAB program). The use of rapid screening has these advantages:

1. reduces costs of collecting and sending non-contaminated shellfish samples to a central testing lab for analysis;
   
   
2. enhances overall safety and improves the economies of the fishery operation by facilitating rapid detection at the site prior to harvest and preventing shipment of contaminated product to the market;
   
   
3. reduces state lab testing resources (personnel time, costly instrumental analyses, field sampling, travel time, etc.) required for analyzing nontoxic samples; and
   
   
4. permits the possibility for expanding the harvest area.

Electrochemical Assay

A tool in development as a collaboration among the Quileute tribe, the National Ocean Service (MERHAB program and Beaufort, N.C. lab), AndCare Corporation, and the Northwest Fisheries Science Center. This rapid screening tool will have the same advantages as the rapid screening assay described above, but in addition, will provide a real-time, quantitative determination of domoic acid in both seawater and shellfish samples.

Molecular Probe Sandwich Assay

Dr. Chris Scholin of the Monterey Bay Aquarium Research Institute and Saigene Corporation (Seattle, WA) have developed molecular probes that are designed to specifically recognize ribosomal RNA from Pseudo-nitzschia species allowing for individual identification and quantification of the various species of Pseudo-nitzschia. The small self-contained device, has the potential for being used in the field and in remote locations. Beach or boat net tows of seawater samples could quickly be identified and quantified as to whether they contain toxic variants of the Pseudo-nitzschia diatoms.

Remote Sensing

Automated sensors

To reduce costs associated with human labor and expensive traditional methods of measurements, automated techniques are being phased into the project. During the summer months, a series of moorings with sensors for temperature, salinity, and fluorescence are deployed using OCNMS vessels at several sites along the Washington coast to provide a detailed record of oceanic environmental parameters. This information will assist ORHAB personnel in developing HAB models which will eventually allow coastal managers to forecast HAB events. The molecular probes, discussed above, have the potential to be adapted for use on these moorings. A prototype has been developed by MBARI and is currently being tested in California.

Satellite Imagery

Battelle scientists are using two different satellites to track the extent and movement of the Juan de Fuca eddy: the NASA/OrbImage SeaWiFS provides ocean color imagery, and is used to detect areas of high biological productivity including algal blooms. The NOAA AVHRR satellite provides daily sea surface temperature imagery and is used to detect area of nearshore upwelling and regions of cooler water representing the Juan de Fuca eddy. Battlelle is also looking at historical data to identify relationships between satellite imagery and chlorophyll concentrations, Pseudo-nitzschia spp. cell numbers, and measured toxin levels. These data, combined with modeling conducted by other ORHAB partners, are being used to determine the scenarios that result in transport of Pseudo-nitzschia spp. cells to the Washington coast.

Detection Methods | Remote Sensing

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