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Identification of Ciguatoxins in Hawaiian Monk Seals Monachus schauinslandi from the Northwestern and Main Hawaiian Islands

Author(s): Bottein, M.-Y.; L. Kashinsky; Z. Wang; C. Littnan; J.S. Ramsdell


Publication Type: Journal Article

Journal Title: Environmental Science and Technology

Date of Publication: 2011

Reference Information: 45(12): 5403-5409

Keywords: Ciguatoxin; ciguatera; Hawaiian monk seal; Monachus schauinslandi; biotoxins; harmful algal bloom; endangered species; phycotoxins

Abstract: Ciguatoxins are potent algal neurotoxins that concentrate in fish preyed upon by the critically endangered Hawaiian monk seal (Monachus schauinslandi). The only report for Hawaiian monk seal exposure to ciguatoxins occurred during a 1978 mortality event when two seal liver extracts tested positive by mouse bioassay. Ciguatoxins were thus proposed as a moderate threat to the Hawaiian monk seal population. To re-investigate monk seal exposure to ciguatoxins we utilized more selective detection methods, the Neuro-2A cytotoxicity assay, to quantify ciguatoxin activity and an analytical method LC-MS/MS to confirm the molecular structure. Tissue analysis from dead stranded animals revealed ciguatoxin activity in brain, liver and muscle, whereas analysis of blood samples from 55 free-ranging animals revealed detectable levels of ciguatoxin activity (0.43 to 5.49 pg/mL P-CTX-1 equiv) in 19% of the animals. Bioassay-guided LC fractionation of two monk seal liver extracts identified several ciguatoxin-like peaks of activity including a peak corresponding to the P-CTX-3C which was confirmed present by LC-MS/MS. In conclusion, this study provide first confirmation that Hawaiian monk seals are exposed to significant levels of ciguatoxins and first evidence of transfer of ciguatoxin to marine mammals. This threat could pose management challenges for this endangered marine mammal species.