Historical Data | Key Results

Historical Data

Domoic acid was first recognized on Washington State beaches in late 1991. Since monitoring began (see beaches marked in red in above figure) in early 1992, domoic acid levels at Kalaloch Beach have typically been higher than at other Washington coastal sites. In 1998 an unusual event occurred- levels of domoic acid reached over 300 ppm at Kalaloch (see figure below). By the spring of 1999, domoic acid levels fell dramatically, reaching below the regulatory level of 20 ppm.

Key Results

So, what do we know about toxic blooms that may be lurking offshore? The results from our nearshore sampling give us more information about the September 2000 bloom. These data show us DA at two depths, surface and 5 meters. The area represented by each panel is the nearshore site on the central Washington coast, samples on different dates in September. No toxin was measured in seawater on September 5, but on September 12, we saw low amounts of DA at the surface at our southern sampling sites (each dot represents a sampling station). Then on September 19, very high levels of DA were measured at both the surface and 5 meters depth. Notice, however, that the maximum amount of toxin was offshore and never really reached the coast. By September 26, all traces of DA were gone.

The physical oceanographic data from moorings tells us that high winds occurred on September 15-18, potentially contributing to the onshore movement of phytoplankton. Both the nearshore and beach sampling data show us that this was a very short-lived event, with no resulting toxin in razor clams.

What have we learned? Now we know what conditions are present during a short-lived Pseudo-nitzschia bloom that does not impact coastal shellfish. Also, we have great clues that tell us where to place offshore moorings to gain information about the offshore presence and levels of toxicity of Washington State Pseudo-nitzschia.

DA in Nearshore sampling water
Top panels: Surface water, Lower panels: 5M

Historical Data | Key Results

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