The toxic effects of three dinoflagellate species from the genus Karenia on invertebrate larvae and finfish

Abstract

Three species of Kareniaceae, Karenia brevis , Karenia brevisulcata and Karenia mikimotoi were assessed for toxicity to juvenile Chinook salmon ( Oncorhynchus tshawytscha ), snapper ( Pagrus auratus ) and six species of marine invertebrate larvae (Greenshell TM mussel, pacific oyster, paua [New Zealand abalone], sea slug, sea urchin and brine shrimp). Karenia brevis was ichthyotoxic to juvenile salmon with a LT 50 of 0.75 h at 0.18 × 10 6 cells L –1 but juvenile snapper were less sensitive (LT 50 of 4.5 h at 5.9 × 10 6 cells L –1 ). Karenia brevisulcata also showed differential toxicity to juvenile salmon and snapper with LT 50 of 0.48 h at 11 × 10 6 cells L –1 and 7.5 h at 16 × 10 6 cells L –1 respectively. However, no acute symptoms were observed in the fish following 48 h exposure to K. mikimotoi at 3.4 × 10 6 cells L –1 . Karenia brevis at the highest level tested (8.7 × 10 6 cells L –1 ) did not cause observable symptoms in any of the invertebrate larvae over 24 h. Karenia mikimotoi only affected paua larvae (LT 50 10 h at 12 × 10 6 cells L –1 ). Karenia brevisulcata was highly toxic to mussel, sea urchin and paua larvae (LT 50 1–6.1 h at 7.5–9.6 × 10 6 cells L –1 ), toxic to sea slug and oyster larvae (LT 50 6 h at 80 × 10 6 cells L –1 and 9.2 h at 34 × 10 6 cells L –1 respectively) but did not affect brine shrimp. Analysis of test cultures by liquid chromatography‐mass spectrometry confirmed that K. brevis produced brevetoxins (52 pg cell –1 ; mainly brevetoxin‐2). Karenia brevisulcata produced brevisulcatic acids (BSXs) and the more toxic Karenia brevisulcata toxins (KBTs). Karenia mikimotoi did not produce brevetoxin, BSXs or KBTs. The present study confirms the broad threats that blooms of K. brevisulcata pose to marine ecosystems and aquaculture, and the hazards of K. brevis to finfish and K. mikimotoi to abalone respectively.

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