ELSEVIER Marine Chemistry 48 (1994) 71-82 Time courses of intracellular and extracellular lipid classes in batch cultures of the toxic dinoflagellate, Gymnodinium cf. nagasakiense Christopher C. Parrish a, Guy Bodennec b, Patrick Gentien b aOcean Sciences Centre and Department of Chemistry, Memorial University of Newfoundland, St. John's, NF, AI C 5S7, Canada bD~partement Environnement Littoral, IFREMER, Centre de Brest, 29280 PlouzanO. France Received 16 July 1993; revision accepted 27 April 1994 Abstract The effect of temperature and light on lipid production was determined for an isolate of Gymnodinium cf. nagasak&nse which is known to be toxic. Samples were taken in a time course in cultures grown at 13 or 18°C and at 35 or 75 #E.m -2 .s -~ . The lipid class composition of Gymnodinium cf. nagasakiense cells and their exudates were analyzed with the Chromarod-Iatroscan system. The main intracellular lipid class, glycolipid, was present at similar concentrations in the cells in all three cultures. Maxima in intracellular concentrations of triacylglycerol, and minima in intracellular free fatty acid concentrations occurred near the time of maximum culture density. Dissolved free fatty acid concentrations were higher during the first 20 days than in the following 10 days of each culture. The culture grown at 13°C had the highest intracellular triacylglycerol concentration and the highest extracellular free fatty acid concentration. The culture grown at 35 #E.m -2- s-l had the highest extracellular glycolipid concentration. Gas chromatographic analyses at the end of the growth experiments showed that pentaenoic fatty acids consisting mainly of 18 : 5n3 were twice as prominent in cells grown at the lower light level. However, the amount of 18 : 5n3 released into the surrounding medium in this culture was negligible. 1. Introduction In recent years there has been a global increase in the number of documented toxic algal blooms. This is partly a result of greater awareness of such events in the scientific community, but it is also likely a consequence of increased coastal pollution and use of coastal waters for aquaculture purposes (Anderson, 1989). Toxic events appear to have expanded in geographic extent and variety. In eastern Canada, for example, while the St. Lawrence estuary and the Bay of Fundy have long been recognized as areas of paralytic shellfish poisoning, the first recorded case of such poisoning occurred in Newfoundland in 1982 (White and White, 1985). In 1987, a very unusual diatom bloom was responsible for the toxicity of mussels in neighbouring Prince Edward Island (Bates et al., 1989). Some phytoplankton are thought to cause fish kills by producing lipid compounds containing polyunsaturated fatty acids (Yasumoto et al., 1990). Such compounds may also be toxic to other algae, thus permitting the toxic alga to fully utilize available nutrients for growth (Gentien and Arzul, 1990a,b) resulting in a catastrophic bloom. By modifying their environment these algae may thus proliferate where they would not otherwise 0304-4203/94/$07.00 © 1994 Elsevier Science B.V. All rights reserved SSDI 0304-4203(94)00028-C