Alexandrium peruvianum (Balech and Mendiola) Balech and Tangen a new toxic species for coastal North Carolina

Abstract

Routine sampling of the water quality stations in the New River Estuary (Jacksonville, North Carolina, USA) during November 2004 revealed the presence of a previously unidentified dinoflagellate. Preliminary observations of its morphology suggested it to be consistent with that of Alexandrium peruvianum (Balech et Mendiola) Balech et Tangen. Observations using brightfield, epifluorescence and scanning electron microscopy confirmed the diagnostic thecal plates to be those of A. peruvanium. Clonal cultures established from cells isolated from the New River Estuary samples were also used for further studies of morphology and for the presence of toxins. Thecal morphology was consistent with that described by Balech clearly separating it from the sister species Alexandrium ostenfeldii. Three classes of toxins were detected from these cultures. An erythrocyte lysis assay (ELA) was used to confirm the presence of hemolytic toxins in A. peruvianum cultures. A cellular EC50 for lysis was 1.418×104 cells, well within the range the maximal cells densities found in the New River and more potent when compared on a cellular basis with Prymnesium parvum. Another toxin class detected in A. peruvianum cultures was the fast acting 13-desmethy C and D spirolides also produced by the sister species A. ostenfeldii. The last toxin type detected in the A. peruvianum cultures was the paralytic shellfish toxins, GTX 2, 3, B1, STX and C1,2. These findings expand the geographic range of occurrence for A. peruvianum in the U.S. to be much greater than previously considered. The morphological characters agreed with previously reported molecular data in separating A. peruvianum from A. ostenfeldii. It is also the first confirmed report that this species produces PSP toxins, spirolides and naturally occurring hemolytic substances. In light of these findings additional attention is needed for the detection of Alexandrium species in all coastal waters of the U.S. This added effort will enhance the evaluation of the relative impacts of the species to shellfish safety and bloom surveillance.