Occurrence of four algae toxins in the marine water of Hong Kong

Algal toxins are natural organic compounds produced by toxic algae in the water and they have caused lots of harms for marine ecology and human health over the past decades. In this study, 24 marine water samples were collected in the marine of Hong Kong. Four algae toxins, including saxitoxin (STX), domoic acid (DA), okadaic acid (OA) and azaspiracid-1 (AZA-1) were analysed by Ultra-performance liquid chromatography (UPLC) – mass spectrometry/mass spectrometry (MS/MS). STX was not existed in all samples while AZA-1 was detected in all samples (range from 5.14 ng/L to 11.9 ng/L). Lower concentrations of DA and OA were detected in the open marine area than in the narrow marine area. The concentrations of DA, OA and AZA-1 in Eastern marine area were higher than in the Western and Southern marine area. The concentration differences of DA were higher in these samples (range from 0 ng/L to 10.3 ng/L) than other three toxins. The concentrations of the detected algae toxins were much less than the WHO recommended level (in µg level). The risk quotients (RQs) of ecological risk assessment and human health assessment were all far less than 1. There was no evidence showing that these four algae toxins had the significant harms for marine organisms and humans in Hong Kong. Three groups were conducted from these 24 samples by the principal components analysis (PCA), suggesting that agriculture, untreated domestic waste water and coastal fisheries contributed to eutrophication, which caused high levels of DA, OA and AZA-1. Further study of the risk of these four algae toxins is necessary in Hong Kong. Copyright © 2019 ICMPE-9.