ELICITATION OF ALEXANDRIUM-OSTENFELDII (DINOPHYCEAE) AFFECTS THE TOXIN PROFILE

Batch cultures of the dinoflagellate Alexandrium ostenfeldii (Paulsen) Balech et Tangen were characterized by an exponential growth phase en ding after 10 days, Three different paralytic shellfish poison (PSP) t oxin patterns (A, B, and C) occurred at days 3, 6 and 10, respectively . The main toxins in pattern A were: 53% GTX6, 26% C4, 17% GTX5; B: 62 % GTX4, 17% GTX6, 16% C3; C: 31% GTX4, 28% GTX6, 26% C4, 13% C3. Batch cultures (with identical pattern A) were challenged (elicted) on day 3 with various organic compounds and extracts of Alexandrium tamarense , After elicitation each toxin concentration changed on both day 6 and 10, A causal relation between properties of the elicitor and the resu lting toxin pattern could not be established. It is proposed that toxi ns responding with small relative standard variations from the mean co ncentration (STX, neoSTX, GTX3, GTX4, GTX6 and C3) are characteristic for the batch culture. Toxins with high variability (GTX1, GTX2, GTX5, C2 and C4) change concentration as a result of stress provoked by the elicitors. The toxicity (estimated from standard values) of some elic ited cultures had increased by a factor of 4 on day 10 indicating that stimulation of blooms of A. ostenfeldii may have substantial conseque nces regarding the problem of paralytic shellfish poisoning.