The sterol composition of harmful dinoflagellates distinguishes environmental characteristics of Chilean Patagonia

Resumen: Harmful Algal Blooms represent a major global concern due to the environmental degradation, economic losses, and threats to human health they cause, and Chile has not remained unaffected. To address the potential role of sterols as chemotaxonomic indicators of harmful dinoflagellates, the sterol composition in monoclonal cultures of toxin-producing (Alexandrium catenella, Alexandrium ostenfeldii, Protoceratium reticulatum) and non-toxin-producing species (Pentapharsodinium dalei and, in this study, Gonyaulax sp.) was examined. Cultures were established from resting cysts preserved in sediments from Northern and Southern Patagonia. A total of 21 sterols were identified in the cultures, showing considerable intra- and interspecific variability in composition and concentration. Total sterol content ranged from 31 to 2674 μg/g dry weight, with dinosterol being the prevalent sterol in all cultures except Gonyaulax sp. Elevated levels of dehydrocholesterol (>50 % of total sterols) characterized P. reticulatum, making this sterol a potential species biomarker. Statistical analyses indicate that the sterol composition across the various cultures tends to differ by sampling area (ANOSIM R = 0.52; p = 0.001), reflecting intraspecific variation. This result could be attributed to the fact that Northern and Southern Patagonia have different populations of the same species and/or is associated with the environmental regimes characteristic of each region.