High-vertical resolution sampling reveals sharp Thin Layers of Toxic Phytoplankton in the Patagonian Fjords, Southern Chile

A study was conducted in the Puyuhuapi Fjord, southern Chile, to compare two sampling methods—conventional oceanographic bottles at two-metre intervals and a fine-scale sampling device—for characterising thin layers (TLs) of Dinophysis acuminata and Dinophysis acuta and their associated lipophilic toxins. The results obtained with the fine-scale sampler revealed significantly higher cell densities and toxin concentrations compared to conventional sampling. Moreover, the coincidence of maximum species and toxin abundances varied depending on the sampling method used. This study underscores the importance of high-resolution tools for revealing fine-scale distribution patterns of toxic species in strongly stratified systems such as Patagonian fjords.