Latitudinal variation in the toxicity and sexual compatibility of alexandrium catenella strains from southern Chile

16 pages, 6 figures, 2 tables.-- This is an open access article distributed under the Creative Commons Attribution License

The bloom-forming toxic dinoflagellate Alexandrium catenella was first detected in southern Chile (39.5–55° S) 50 years ago and is responsible for most of the area’s cases of paralytic shellfish poisoning (PSP). Given the complex life history of A. catenella, which includes benthic sexual cysts, in this study, we examined the potential link between latitude, toxicity, and sexual compatibility. Nine clones isolated from Chilean Patagonia were used in self- and out-crosses in all possible combinations (n = 45). The effect of latitude on toxicity, reproductive success indexes, and cyst production was also determined. Using the toxin profiles for all strains, consisting of C1, C2, GTX4, GTX1, GTX3, and NeoSTX, a latitudinal gradient was determined for their proportions (%) and content per cell (pg cell−1), with the more toxic strains occurring in the north (−40.6° S). Reproductive success also showed a latitudinal tendency and was lower in the north. None of the self-crosses yielded resting cysts. Rather, the production of resting cysts was highest in pairings of clones separated by distances of 1000–1650 km. Our results contribute to a better understanding of PSP outbreaks in the region and demonstrate the importance of resting cysts in fueling new toxic events. They also provide additional evidence that the introduction of strains from neighboring regions is a cause for concern

This work was funded by a national project from the Spanish Ministry of Science and Innovation and the European Community (FEDER) (Project DIANAS-CTM2017-86066-R) to RIF, a grant for Galician Networks of Excellence (GRC-VGOHAB IN607A-2019/04) from the Innovation Agency of the Xunta de Galicia (GAIN) to RIF, and supported by projects REDES170101 and REDI170575 from the International Cooperation Program of the Chilean National Research and Development Agency (ANID) to PAD

Peer reviewed