Monthly monitoring of domoic acid producer Pseudo-nitzschia multiseries (Hasle) Hasle using species-specific DNA probes and WGA lectins and abundance of Pseudo-nitzschia species (Bacillariophyceae) from Chinhae Bay, Korea

A twelvemonth field survey of the genus Pseudonitzschia was carried out in Chinhae Bay, an area of commercial culturing and harvesting of oysters.The study used molecular DNA probes and WGA lectins to determine monthly species abundance and relate this to environmental conditions and nutrients. Ten species of Pseudonitzschia were identified during the study: Pseudonitzschia multiseries, P. pungens, P. multistriata, P. delicatissima, P. cuspidata, P. subfraudulenta, P. granii, P. fraudulenta, P. subpacifica, and an unidentified Pseudonitzschia sp. Of the Pseudonitzschia species, Pseudonitzschia pungens had the highest cell abundance, followed by P. delicatissima and P. multistriata.The presence of Pseudonitzschia multiseries was correlated with domoic acid (DA) contamination of shellfish, for example at Stations (Stn) P2, P3 and P4.Where Pseudonitzschia multiseries was recorded, trace levels of DA were detected, but at Stn P1 neither Pseudonitzschia multiseries nor DA were detected during the period of this study. Pseudonitzschia multiseries is regarded as the most toxic of the DAproducing species known in Korea. Korean isolates of Pseudonitzschia multiseries were strongly labeled by WGA lectin and the Pseudonitzschia multiseries speciesspecific DNA probe, and were distributed in seawater of lower temperature (less than or equal to15 degreesC) and linked with lower nutrient concentrations, although cell numbers were significantly lower than for Pseudonitzschia pungens.The use of the probes puD1, deD1 and frD1 led to the recognition of Pseudonitzschia pungens, P. delicatissima and P. fraudulenta, respectively. Although Pseudonitzschia species varied depending on month and sampling site, most were present at higher cell densities in lower temperature waters except for Pseudonitzschia multistriata. It was demonstrated that these methods provide a simple and rapid technique for the identification of a variety of Pseudonitzschia in Korean waters, and offer the opportunity for a series of realtime species detection in the future.