Leonardo Guzmán, Hernán Pacheco, Gemita Pizarro and César Alarcón, Instituto de Fomento Pesquero, Punta Arenas, Chile
lguzman@ifop.cl

Abstract

In Chile, PSP, DSP and ASP have been detected between 41°-55° S.L., but ASP has been recently encountered at 27° and 30°S. Blooms of Alexandrium catenella and PSP outbreaks have occurred in the Magellan region in 1972, 1981, 1989 and since 1991, a bloom series persisting up to date. On 1994 blooms extended to the Aysén region, where also DSP is present. 387 PSP human intoxication have been registered, including 26 fatal cases, 20 of which occurred in the Magellan region.

Information available since 1972 is analysed, including mussel toxicity, density and relative abundance of A. catenella, and phytoplankton structure. Blooms and PSP distributions are different between years, if A. catenella density, period of the year, geographic coverture and its duration, and toxicity level are considered. In the Magellan region the highest toxicity records in mussels and the greatest geographic coverture occurred in 1994.

A. catenella distribution ranges from Cailin (43°09'55"S; 73°31'30"W) to Seno Ponsonby (55°08'19"S; 68°43'54"W). Areas with higher probabilities of occurrence of the motile stage of A. catenella and toxic shellfish have been detected. South of 48°06'S four "toxicity geographic nuclei" have been identified. A. catenella blooms duration and its geographic coverture as well as PSP presence in Chile cannot be explained by local factors, which seem to be linked to La Niña final period and the initiation of a strong El Niño event.