Within the past few decades, harmful algal blooms (HABs) have occurred frequently in Indonesian waters, resulting in environmental degradation, economic loss and human health problems. So far, HAB related studies mainly addressed ecological traits and species distribution, yet toxin measurements were virtually absent for Indonesian waters. The aim of the present study was to explore variability of the potentially toxic marine diatom genus Pseudo-nitzschia, as well as its neurotoxin domoic acid as a function of environmental conditions in Ambon Bay, eastern Indonesia. Weekly phytoplankton samples, oceanographic (CTD, nutrients) and meteorological (precipitation, wind) parameters were analyzed at 5 stations in the bay during the dry and wet seasons of 2018. Liquid chromatography – tandem mass spectrometry (LC–MS/MS) was used to detect particulate DA (pDA). Vegetative cells of Pseudo-nitzschia spp. and pDA were found in 98.6% and 51.4% of the samples, respectively. pDA levels were low, yet detected throughout the campaign, implying that Ambon Bay might potentially be subject to amnesic shellfish poisoning. The highest levels of both Pseudo-nitzschia spp. cell abundance and pDA were found in the wet season, showing a strong positive correlation between both parameters, compared to the dry season, (r = 0.87 and r = 0.66 (p < 0.01), respectively). Statistical analyses revealed that temperature and mixed layer depth positively correlated with Pseudo-nitzschia spp. and pDA during the dry season, while ammonium showed positive correlations in both seasons. This study represents the first successful investigation of the presence and variability of Pseudo-nitzschia spp. and its neurotoxin DA in Indonesian waters.

在过去的几十年中，印度尼西亚水域经常发生有害藻华（HAB），导致环境退化，经济损失和人类健康问题。到目前为止，HAB的相关研究主要针对生态特征和物种分布，但印尼水域实际上没有毒素测定。本研究的目的是探讨潜在有毒的海洋硅藻属假性尼兹菌属的变异性。以及其神经毒素多摩酸随环境条件的变化，在印度尼西亚东部的安汶湾。在2018年的干燥和潮湿季节，在海湾的5个站点对每周浮游植物样本，海洋学（CTD，营养物）和气象学（降水，风）参数进行了分析。使用了液相色谱-串联质谱（LC-MS / MS）以检测颗粒DA（pDA）。拟南芥属的营养细胞。分别在98.6％和51.4％的样品中发现了pDA和pDA。pDA水平很低，但在整个运动中仍被检测到，这意味着安汶湾可能会遭受遗忘性贝类中毒。两种假性尼茨菌病的最高水平spp。在干燥季节发现细胞丰度和pDA，与干旱季节相比，两个参数之间显示出很强的正相关性（分别为r = 0.87和r = 0.66（p <0.01））。统计分析表明，温度和混合层深度与拟南芥属物种呈正相关。与干旱季节的pDA和pDA相关，而铵盐在两个季节均显示出正相关。这项研究代表了对拟南芥属物种的存在和变异性的首次成功调查。及其在印度尼西亚水域的神经毒素DA。