Ichthyotoxicity of four species of gymnodinioid dinoflagellates (Kareniaceae, Dinophyta) and purified karlotoxins to larval sheepshead minnow

• Published in: Harmful Algae
• Main Authors: Mooney, B, Hallegraeff, GM, Place, AR
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier Science BV 2010
• Subjects: Biological Sciences; Plant biology; Phycology (incl. marine grasses); Southern Ocean; Huon
• Online Access: http://www.sciencedirect.com; https://doi.org/10.1016/j.hal.2010.04.005; http://ecite.utas.edu.au/67973

Two species of Kareniaceae, Karlodinium veneficum (Swan and Huon River isolates) and Karlodiniumconicum, and their respective purified karlotoxins (KmTx), were investigated for ichthyotoxicity on larvalsheepshead minnow. Two non-karlotoxin producing species, Karenia mikimotoi and Karlodiniumballantinum were also tested. Algal treatments included live and lysed cells (homogenized and CuSO4treated) with fishmortalities observed from lysed Ka. veneficum and Ka. conicum but none observed fromK. mikimotoi and Ka. ballantinum. The variance in ichthyotoxicity between live and lysed cells of Ka.veneficum(Swan and Huon River) and Ka. conicum(Southern Ocean) confirm that toxin is cell bound andichthyotoxicity increases upon lysis. Ichthyotoxic blooms of Ka. veneficum in situ in the Swan River,Western Australia and Chesapeake Bay, Maryland, USA are unrelated to algal cell density as mortalitywas observed with low densities. In laboratory treatments, no fish mortalities were observed uponexposure to live intact cells of all four species at algal concentrations up to 2.5-105 cells/mL in repletenutrient growth conditions. Lysed low density (3-104 cells/mL) Ka. veneficum (Swan and Huon River)grown under P-limited nutrients caused quicker fish mortality than those cultured in replete nutrientconditions. Pure toxin isolated from Ka. veneficum (Swan and Huon River) and Ka. conicum (SouthernOcean) were toxic to sheepshead minnow larvae, with the lethal dose lowest for KmHuonTx 2 (508.2 ng/mL), followed by KmSwanTx 2-1 (563.2 ng/mL), and KmconicumTx (762.4 ng/mL).