51 Pseudo-nitzschia 擬菱形藻 Phylum: Heterokontophyta 门：不等鞭毛门 Class: Bacillariophyceae 纲：羽紋硅藻纲 Order: Bacillariales 目：硅藻目 Family: Bacillariaceae 科：硅藻科 Morphology Frustules are elongated, lanceolate, narrow navicular, fusiform, or linear in outline. In girdle view, valves are rectangular or fusiform. Cells are solitary or form mobile colony by overlapping valve ends. According to AlgaeBase, there are 59 Pseudo-nitzschia species which are difficult to identify under light microscope only. The main differences between species include percentages of overlapping parts, morphology of valves and valve ends, and ultrastructure of frustules. 形態 細胞殼面一般呈細長披針形，狹舟形，梭形，或線形。殼環面觀為矩形或梭形。細 胞單獨生活或者通過殼面末端相疊形成可移動的鏈狀群體。根據AlgaeBase，偽菱 形藻目前59個物種，但基於顯微鏡很難將其鑒定到物種水準。物種鑒定主要依據 是群體細胞相連部分的比例，殼面外形，殼端形狀，以及細胞壁超顯微結構的差異。 Ecology and distribution Pseudo-nitzschia species are distributed globally from polar regions to tropical waters and mainly found in nutrient rich coastal areas or estuaries. Pseudo-nitzschia are dominant group in Hong Kong coastal waters especially in summer and autumn. Various Pseudo-nitzschia species are bloom forming species and have formed 14 blooms since 1986 in Hong Kong coastal waters. Some species are capable to produce domoid acid that causes amnesic shellfish poisoning (ASP) and may cause significant damage to the aquaculture industry, ecosystem stability, and human health.
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