The population dynamics of different Pseudo-nitzschia species, along with particulate domoic acid (pDA) concentrations, were studied from May 2012 to December 2013 in the Bay of Seine (English Channel, Normandy). While Pseudo-nitzschia spp. blooms occurred during the two years of study, Pseudo-nitzschia species diversity and particulate domoic acid concentrations varied greatly. In 2012, three different species were identified during the spring bloom (P. australis, P. pungens and P. fraudulenta) with high pDA concentrations (∼1400 ng l⁻¹) resulting in shellfish harvesting closures. In contrast, the 2013 spring was characterised by a P. delicatissima bloom without any toxic event. Above all, the results show that high pDA concentrations coincided with the presence of P. australis and with potential silicate limitation (Si:N < 1), while nitrate concentrations were still replete. The contrasting environmental conditions between 2012 and 2013 highlight different environmental controls that might favour the development of either P. delicatissima or P. australis. This study points to the key role of Pseudo-nitzschia diversity and cellular toxicity in the control of particulate domoic acid variations and highlights the fact that diversity and toxicity are influenced by nutrients, especially nutrient ratios.

研究人员于2012年5月至2013年12月在塞纳湾（英吉利海峡，诺曼底）研究了不同假拟南芥物种的种群动态以及颗粒状的二氢氰酸（pDA）浓度。而假性尼兹菌属。在两年的研究中发生了水华，假奈瑟菌菌种的多样性和颗粒状海藻酸的浓度相差很大。在2012年，三种不同的物种弹簧开花（期间确定芦苇，P. pungens和P. fraudulenta）具有高PDA浓度（纳克~1400升^-1），导致贝类收获闭包。相比之下，2013年春季的特点是P. delicatissima开花没有任何毒性事件。最重要的是，结果表明，高的pDA浓度与澳大利亚假单胞菌的存在和潜在的硅酸盐限制（Si：N <1）同时存在，而硝酸盐的浓度仍然充足。2012年至2013年之间环境条件的对比突出表明，不同的环境控制措施可能有利于P. delicatissima或P. australis的发展。这项研究指出了假性奈瑟菌多样性和细胞毒性在控制颗粒状海藻酸变化中的关键作用，并强调了这样一个事实，即多样性和毒性受养分特别是养分比例的影响。