Morpho-molecular and environmental evidence of the ocurrence of Karenia longicanalis (Dinophyceae: Kareniaceae) as a bloom former in the Eastern Pacific Ocean.

Karenia longicanalis, an athecate dinoflagellate, was first described during a bloom in Victoria Harbour (Hong Kong, China). This study confirms the presence of K. longicanalis as a bloom former in the eastern Pacific Ocean. Specimens were collected in March 2019 at three sampling stations in Acapulco Bay, Mexico. Water temperature, salinity, dissolved oxygen, and pH were measured in situ at the time of sample collection. Cell morphology was examined by optical and scanning electron microscopy. A molecular analysis based on the amplification of the large subunit (LSU) rDNA region revealed that the LSU sequences formed a monophyletic group with other GenBank sequences belonging to K. longicanalis. The resulting phylogeny demonstrates that Karenia is closely related to Asterodinium, Gertia, and Shimiella. The morphology of the specimens was consistent with previous descriptions.

The genus Eutreptiella (Euglenophyceae/Euglenozoa) across its global distribution range.

The genus Eutreptiella (Euglenophyceae/Euglenozoa) comprises unicellular organisms known for their photosynthetic capacity and significant role in marine ecosystems. This review highlights the taxonomic, ecological, and biotechnological characteristics of Eutreptiella species, emphasizing their morphological and genomic adaptations. Eutreptiella species exhibit high phenotypic plasticity, enabling adaptation to various environmental conditions, from nutrient-rich waters to high-salinity conditions. They play a crucial role in primary production and nutrient cycling in marine ecosystems. Genetic and transcriptomic studies have revealed their complex regulatory mechanisms and potential for biofuel and nutraceutical production. Eutreptiella blooms significantly impact local ecosystems, influencing nutrient availability and community dynamics. Additionally, interactions with associated bacteria enhance their growth and metabolic capabilities. The genus shows substantial genetic variability, suggesting potential misidentifications or a polyphyletic nature. Further comprehensive studies are needed to clarify their taxonomy and evolutionary relationships. Understanding and managing Eutreptiella populations is essential to leverage their biotechnological potential and ensure the health of marine ecosystems.