PSEUDONITZSCHIA SPECIES FOUND IN DIGESTIVE TRACTS OF NORTHERN ANCHOVIES (ENGRAULIS-MORDAX)

The diatom species Pseudonitzschia australis Frenguelli has been impli cated as the source of the domoic acid that contaminated anchovy speci es in Monterey Bay, California, during 1991. In other geographic areas , as well as in laboratory cultures of isolates obtained from various geographic areas, other Pseudonitzschia species have been shown to pro duce domoic acid. The stomach contents of anchovies caught in Monterey Bay during the following summer were analyzed to identify and determi ne the abundance of each of the Pseudonitzschia species present. Pseud onitzschia species present in net-tow samples taken at the same time f rom Monterey Bay were also recorded. In the stomach samples, nine diff erent Pseudonitzschia species were found, including four that have pro duced domoic acid either under natural or laboratory conditions. These findings illustrate the risk of possible neurotoxin accumulation inhe rent in the diets of the anchovies studied. The planktophagous diet of the anchovies reflected the plankton composition of the surrounding w ater and also demonstrates the anchovies' ability to filter pennate di atoms from the near-surface seawater.