Description
Benthic dinoflagellates have been found in Hong Kong waters, most of them are producers of algal toxins and pose threats to marine ecosystems. One of the toxicities of these algal toxins is to cause hemolysis in fish. For example, maitotoxin (MTX) is one of the potent toxins that can induce hemolysis. In this study, we aimed to assess the hemolytic toxicity of six species of locally collected toxic benthic dinoflagellates, namely Coolia tropicalis, C. maleyensis, Fukuya retzuleri, Fukuya sp. HK Type I, Amphidinium carterae and Prorocentrum cf. lima. Each species of algal extract will be examined by hemolytic assay using the freshly collected fish blood of local reef fishes including Cephalopholis boenak and Acanthopagrus schlegelli. More than 50% erythrocytes were lysed in Cephalopholis boenak and Acanthopagrus schlegelli exposed to extracts from Coolia tropicalis, Fukuya retzuleri and Amphidinium carterae at a concentration of 0.1 mg ml-1. The hemolytic activities were significantly lower in the other three algal species. Results from chemical analysis showed that a novel algal toxin 44-methylgambierone (MTX-3) has been detected in Coolia tropicalis and Fukuya retzuleri. The hemolytic and toxic effects of these two algal species are currently being elucidated using the marine medaka larvae which are treated with microinjection of the different concentrations of the toxic algal extracts. Some of our preliminary results showed that hemorrihage in marine medaka larvae occurred when micro-injected with water-soluble extract of Coolia tropicalis at doses over 340 ng/fish. Our coming investigations will focus on endpoints including the blood flow rate and morphology of red blood cells. The findings of this study showed that some of the benthic dinoflagellates from Hong Kong are ichthyotoxic and 44-methylgambierone may be one of the compounds that is responsible for the hemolysis in fish.| Period | 10 Jun 2019 → 14 Jun 2019 |
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| Event type | Conference |
| Location | Hong KongShow on map |