Toxic Dinophysis acuminata in southern Chile: A comparative approach based on its first local in vitro culture and offshore-estuarine bloom dynamics

Abstract

In Chile, Dinophysis acuminata is a conspicuous mixotrophic dinoflagellate that inhabits the Offshore Pacific Coast (OPC) and the Patagonian fjords (PF). In this study, we investigated D. acuminata phylogeny, morphology, and the effect of environmental factors on cell growth and toxin production of isolates from the OPC and the PF. A comparative approach was performed between in vitro cultures, maintained for the first time in Chile, and phytoplankton field monitoring. Phylogenetic analyses revealed that Chilean D. acuminata sequences clustered in the “Dinophysis acuminata complex” with cell morphology consistent with the “Type A” morphotype. Different reaction norms among the strains from the different oceanic conditions were observed, with the highest growth rate and maximum cell density of the strain isolated from the PF, cultured at 15 °C of temperature and 95 μmol m−2 s−1 light intensity. Pectenotoxin 2 (PTX2) was the only toxin detected in all strains isolated from both OPC and PF. Monitoring data (from 2013 to 2021) of D. acuminata and its prey Mesodinium rubrum were also analyzed to determine the effect of temperature, salinity, depth, and geographic distribution on species abundance and presence probability (PP), along with potential links with climatic patterns such as the Southern Annular Mode (SAM) and El Niño Southern Oscillation. Cell distribution patterns of D. acuminata and M. rubrum were highly related and influenced by low salinity and high temperature in the estuarine zone (PF). Meanwhile, a negative relationship between SAM and D. acuminata abundance was observed. Coupling, the first local D. acuminata culture and field data, allows a better understanding of the spatial–temporal and environmental effects on D. acuminata distribution and growth.