The brevetoxin and brevenal composition of three Karenia brevis clones at different salinities and nutrient conditions

Karenia brevis forms extensive, annual blooms in the Gulf of Mexico releasing potent neurotoxins (brevetoxins) having significant impacts on human health, mortalities of marine mammals, birds and fish. This study examines toxin composition and growth of three clones of K. brevis grown at different nutrient conditions, salinities and temperatures. The three clones studied were K. brevis Wilson, SP3 N-tox and SP3 S-tox clones. Brevetoxins (PbTx-1, -2, -3, -6 and -9) and brevenal were examined using LC-MS/MS. Dialysis studies clearly indicated that PbTx-1, -2 and brevenal were found within intact cells while the other toxins were released in the surrounding medium. Nutrient limitation did not show consistent effects on toxin profiles (brevenal and PbTx-1, -2, -3, -6 and -9) but toxin profiles were significantly related to clone type. The Wilson clone produced a significantly greater amount of brevenal than either SP3 clone. The SP3 clones each responded differently to nutrient limitation in toxin fractions produced. Growth at differing salinities and temperatures confirmed previous reports of K. brevis preference of higher salinities and elevated temperatures but was variable for toxins. These results support the notion that clonal differences in toxin production and profile appears to be less dependent on environmental variables but more related to inherent genetic variations resulting in the differences in clonal responses observed.