Mc. Villac et al., PSEUDONITZSCHIA-AUSTRALIS FRENGUELLI AND RELATED SPECIES FROM THE WEST-COAST OF THE USA - OCCURRENCE AND DOMOIC ACID PRODUCTION, Journal of shellfish research, 12(2), 1993, pp. 457-465
Awareness of the threat of the phycotoxin domoic acid, the cause of Am
nesic Shellfish Poisoning (ASP), reached the U.S.A. west coast in the
fall of 1991. Domoic acid in razor clams, mussels, and Dungeness crabs
led to the closure of fisheries along the coasts of California, Orego
n, and Washington. The death of pelicans that had fed on contaminated
anchovies in Monterey Bay, California, set off the alarm by mid-Septem
ber. The diatom Pseudonitzschia australis Frenguelli, detected in high
concentrations in Monterey Bay at that time, was found to be a source
of domoic acid. The present survey shows that, during the fall of 199
1, P. australis and other Pseudonitzschia spp. were also observed in o
ther sites on the west coast from Southern California to the mouth of
the Columbia River (Newport, Coos Bay, and Ilwaco). In the fall of 199
2, besides P. australis, other Pseudonitzschia spp. were present in Mo
nterey Bay: P. americana and P. pungens, along with the known domoic a
cid producers P. delicatissima, P. pungens f. multiseries, and P. pseu
dodelicatissima. There was no report of a domoid acid outbreak in the
Bay in 1992. There is strong evidence from the literature that, except
for P. americana, all Pseudonitzschia species found in 1991 and 1992
have been part of the diatom community of the U.S.A. west coast at lea
st since the 1940's. The study of their distributional patterns can pr
ovide a predictive tool for the future onset of potential harmful bloo
ms, and hence help protect the consumer and the seafood industry. Clon
es of P. australis from Monterey Bay, Coos Bay and Ilwaco were establi
shed in 1991, and clones of P. australis, P. americana, P. delicatissi
ma, P. pungens, and P. pungens f. multiseries from Monterey Bay were e
stablished in 1992. Domoic acid was detected in P. australis (0.02-0.4
pg . cell-1) and in P. pungens f. multiseries (0.06-1.5 pg . cell-1)
while P. americana, P. delicatissima, and P. pungens tested negative.
The low toxicity found for these Pseudonitzschia clones may be attribu
ted to testing the cell contents only and to growth and harvesting con
ditions in the lab. The implications of background levels of domoic ac
id to shellfish contamination in the field and, therefore, to long-ter
m exposure of low concentrations of this toxin to consumers have yet t
o be explored.