| Resumo: |
During the expeditions Cimar - Fiordos 2, 3 and 4 (1996, 1997 and 1999), samples of marine sediments were collected in Southern Chile, between Melinka (Lat. 43° 45' S) and Beagle Channel (Lat. 54° 56' S) to study the distribution and abundance of dinoflagellate cysts, particularly the toxic dinoflagellate Alexandriurn catenella. Samples were collected from 33 stations at depths of 1 to 15 meters. The study included photographic record and taxonomic identification of cysts to genus and, whenever possible, to species, with emphasis on the identification of cysts of A. catenella. Cysts from samples collected in cruises 3 and 4, were incubated in f/2-Se culture medium at 13 °C with controlled photoperiod (14:10, L:D), to induce germination and confirm species identification. Through this method, it was possible to establish monoclonal cultures of A. catenella. Cysts of dinoflagellates of at least 18 different forms or species were detected within the samples analyzed. The nine species of dinoflagellates identified belong to 5 genera (Protoperidium, Protoceratium, Scrippsiella, Polykrikos and Alexandrium). The cysts of A. catenella were present in samples of 11 stations. They were most abundant at estero Quitralco (Aysén Region), and at Puerto Engaño (Magallanes Region), with 76,7 ± 23,7 y 72,7 ± 33,8 cysts/mL, respectively. Environmental factors, including oceanographic and geographic conditions, and the characteristics of sediments, may affect the distribution and abundance of the cysts of A. catenella. Those locations may become sources for the generation of toxic blooms in the Aysén and Magallanes Regions.
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