Checklist of Potentially Harmful Cyanobacterial Species Isolated from Portuguese Water Bodies

HCBs (Harmful Cyanobacterial Blooms) are increasing in freshwaters across the globe, particularly at lower latitudes. In Southern Europe, a decrease in annual precipitation and an increase in drought periods have enhanced the occurrence of HCBs, impacting both freshwater ecosystems and human health. This review gathers information on isolated cyanobacterial strains with the potential to form cyanobacterial blooms or to be toxic that have been reported over the past half-century in Portugal. Strains of Microcystis aeruginosa are the most represented ones, many of them microcystin producers. Toxic M. aeruginosa strains have been isolated from lakes (Mira, Barrinha de Mira, and Blue), river sections (Tâmega and Guadiana), and reservoirs (Torrão, Vilar, Montargil, Patudos, Caia, Monte da Barca, Corgas, and Magos). Many other strains from potentially toxic species are listed, namely from Aphanizomenon gracile, Aphanizomenon flos-aquae, Sphaerospermopsis aphanizomenoides, Cuspidothrix issatschenkoi, Dolichospermum flos-aquae, Dolichospermum circinalis, Chrysosporum bergii, Raphidiopsis raciborskii or Planktothrix agardhii. Many of the isolated strains were able to produce cyanotoxins such as microcystins, saxitoxins, cylindrospermopsin, or anatoxin. Most isolates belong to the Portuguese culture collections ESSACC (Estela Sousa e Silva Algal Culture Collection); LEGE-CC (Blue Biotechnology and Ecotoxicology Culture Collection); and ACOI (Coimbra Collection of Algae). Despite many strains already having associated molecular data corroborating a correct identification, a large number of strains are still lacking DNA-based information for phylogenetic affiliation. The present checklist is intended to facilitate access to information regarding strains of potentially toxic cyanobacterial species from Portugal in order to contribute to a better understanding of species-specific HCBs at both regional and global scales.