Similarities and differences between Australia and New Zealand in Harmful Algal species occurrences and Harmful Algal Events impacting on human society (HAEDAT) are reported and factors that explain their differences explored. Weekly monitoring of harmful phytoplankton and biotoxins commenced in Australia in 1986 and in New Zealand in 1993. Anecdotal historic HAB records in both countries are also catalogued. In Australia, unprecedented highly toxic Paralytic Shellfish Toxin (PST)-producing blooms of Alexandrium catenella have impacted the seafood industry along the 200 km east coast of Tasmania from 2012 to present. Toxic blooms in 1986-1993 by Gymnodinium catenatum in Tasmania were effectively mitigated by closing the affected area for shellfish farming, while a bloom by this same species in 2000 in New Zealand caused significant economic damage from restrictions on the movement of greenshell mussel spat. The biggest biotoxin event in New Zealand was an unexpected outbreak of Neurotoxic Shellfish Poisoning (NSP) in 1993 in Hauraki Gulf (putatively due to Karenia cf. mikimotoi) with 180 reported cases of human poisonings as well as reports of respiratory irritation north of Auckland. Strikingly, NSP never recurred in New Zealand since and no NSP events have ever been reported in Australia. In New Zealand, Paralytic Shellfish Poisoning (PSP) was the predominant seafood toxin syndrome, while in Australia Ciguatera Fish Poisoning (CFP) was the major reported seafood toxin syndrome, while no CFP has been recorded from consumption of New Zealand fish. In Australia, Diarrhetic Shellfish Poisoning (DSP) illnesses were recorded from two related outbreaks in 1997/98 following consumption of beach harvested clams (pipis) from a previously non-monitored area, whereas in New Zealand limited DSP illnesses are known. No human illnesses from Amnesic Shellfish Poisoning (ASP) have been reported in either Australia or New Zealand. Selected examples of HABs appearing and disappearing (NSP in New Zealand, Alexandrium catenella in Tasmania), species expanding their ranges (Noctiluca, Gambierdiscus), and reputed ballast water introductions (Gymnodinium catenatum) are discussed. Eutrophication has rarely been invoked as a cause except for confined estuaries and fish ponds and estuarine cyanobacterial blooms. No trend in the number of HAEDAT events from 1985 to 2018 was discernible.

报告了澳大利亚和新西兰在有害藻类发生和影响人类社会的有害藻类事件（HAEDAT）方面的异同，并探讨了解释其差异的因素。每周于1986年在澳大利亚和1993年在新西兰开始对有害浮游植物和生物毒素的每周监测。两个国家的HAB轶事历史记录也都已编目。在澳大利亚，从2012年至今，史无前例的剧毒的麻痹性贝类毒素毒素（PST）产生的亚历山大大叶连翘对华州塔斯马尼亚岛东海岸200公里处的海鲜产业产生了影响。Gymnodinium catenatum在1986-1993年间的有毒花朵塔斯马尼亚州的贝类养殖通过关闭受影响的区域进行贝类养殖而得到有效缓解，而该相同物种在2000年在新西兰的盛放活动则由于限制了贝类贻贝的运动而造成了严重的经济损失。在新西兰最大的生物毒素事件是神经性贝类中毒的意外爆发的豪拉基湾（NSP）于1993年（推定由于米氏比照。凯伦藻）报告了180起人中毒事件，以及奥克兰北部发生呼吸道刺激的报告。令人惊讶的是，自从那时以来，NSP在新西兰再也没有发生过，并且在澳大利亚也从未发生过NSP事件的报道。在新西兰，麻痹性贝类毒素中毒（PSP）是主要的海鲜毒素综合症，而在澳大利亚，瓜瓜特拉鱼中毒（CFP）是主要的海鲜毒素综合症，而新西兰鱼的食用未发现CFP。在澳大利亚，1997/98年两次食用暴发的腹泻性贝类中毒（DSP）病原是在食用了先前非监测地区的滩涂蛤c（pipis）之后发生的，而在新西兰，有限的DSP病是已知的。在澳大利亚或新西兰，均未见因遗忘性贝类中毒（ASP）引起的人类疾病。塔斯马尼亚州的亚历山大连翘属植物，扩大其范围的物种（夜蛾属，甘比迪斯cuscus）和著名的压舱水引入物（体操连翘属植物）都得到了讨论。除了密闭河口和鱼塘以及河口蓝藻水华以外，很少有人提到富营养化。1985年至2018年的HAEDAT事件数量没有趋势可辨。