The dinoflagellate genus Karenia includes 10 known species and 9 are reported to be harmful algal species (https://www.marinespecies.org/hab/). In the Gulf of Mexico, at least 6 species are known. Of most concern is K. brevis, which produces brevetoxins that cause neurotoxic shellfish poisoning (NSP). Consumption of toxin-containing shellfish has a significant impact on human health. In this project, de novo reference transcriptomes were generated for four Karenia species: K. brevis, K. mikimotoi, K. papilionacea, K. selliformis). These de novo transcriptomes will serve as reference for field and laboratory experiments.