Dinoflagelados formadores de mareas rojas en aguas costeras argentinas: perspectivas sobre Gymnodinium catenatum (Dinophyceae) y primer registro de G. impudicum

As part of a monitoring program for harmful microalgae in the coastal waters of the Province of Buenos Aires, two chain-forming strains of the genus Gymnodinium (Dinophyceae), LPCc043 and LPCc044, were isolated from samples collected in Samborombón Bay. This study aims to provide a morphological, phylogenetic and toxicological characterization of the isolated strains. Among the chain-forming marine species of Gymnodinium, only G. catenatum and G. impudicum are known to produce harmful algal blooms (HABs). Morphological analysis using scanning light and electron microscopy (OM, MEB) revealed that the LPCc043 strain had larger cells, a higher number of cells per colony, and a sulcus-independent acrobase penetrating the epiconus, whereas the LPCc044 strain had smaller cells, a smaller number of cells per colony, and an acrobase as an extension of the sulcus. Phylogenetic analysis based on partial sequencing of LSU ribosomal DNA placed the sequence corresponding to the LPCc043 strain in the clade of G. catenatum and the sequence corresponding to the LPCc044 strain in the clade of G. impudicum, with bootstrap values and subsequent Bayesian probability of 99–1.0 and 100–1.0, respectively. Toxicological analysis by hydrophilic interaction liquid chromatography with tandem mass spectrometry (HILIC-UHPLC-MS/MS) detected mollusc paralyzing toxins (TPMs) in G. catenatum, predominantly N-sulfocarbamoyl-11-hydrosulfate toxin 1/2 (C1/C2) and decarbamoyl goniautoxin 2/3 (dcGTX2/3). In contrast, no TPM was detected in G. impudicum. This study contributes to the knowledge of the diversity of harmful algal species along the Argentine coast and highlights the importance of monitoring these species for public health and environmental management.