In coastal and offshore waters, Harmful Algal Blooms (HABs) currently threaten the well-being of coastal countries. These events, which can be localized or involve wide-ranging areas, pose risks to human health, marine ecosystems, and economic resources, such as tourism, fisheries, and aquaculture. Dynamics of HABs vary from one site to another, depending on the hydrographic and ecological conditions. The challenge in investigating HABs is that they are caused by organisms from multiple algal classes, each with its own unique features, including different life histories. The complete algal life cycle has been determined in <1% of the described species, although elucidation of the life cycles of bloom-forming species is essential in developing preventative measures. The knowledge obtained thus far has confirmed the complexity of the algal life cycle, which is composed of discrete life stages whose morphology, ecological niche (plankton/benthos), function, and lifespan vary. The factors that trigger transitions between the different stages in nature are mostly unknown, but it is clear that an understanding of this process provides the key to effectively forecasting bloom recurrence, maintenance, and decline. Planktonic stages constitute an ephemeral phase of the life cycle of most species whereas resistant, benthic stages enable a species to withstand adverse conditions for prolonged periods, thus providing dormant reservoirs for eventual blooms and facilitating organismal dispersal. Here we review current knowledge of the life cycle strategies of major groups of HAB producers in marine and brackish waters. Rather than providing a comprehensive discussion, the objective was to highlight several of the research milestones that have changed our understanding of the plasticity and frequency of the different life cycle stages as well as the transitions between them. We also discuss the relevance of benthic and planktonic forms and their implications for HAB dynamics.

在沿海和近海水域，有害藻华（HABs）目前威胁着沿海国家的福祉。这些事件可能是局部的，也可能涉及范围广泛，对人类健康，海洋生态系统和经济资源（如旅游业，渔业和水产养殖业）构成风险。HAB的动态因地点而异，具体取决于水文和生态条件。研究HAB的挑战在于，它们是由来自多个藻类的生物引起的，每个藻类都有其独特的特征，包括不同的生活史。在阐明的物种中，只有不到1％的物种确定了完整的藻类生命周期，尽管阐明形成水华的物种的生命周期对于制定预防措施至关重要。到目前为止，所获得的知识已经证实了藻类生命周期的复杂性，它由离散的生命阶段组成，这些生命阶段的形态，生态位（浮游生物/底栖动物），功能和寿命各不相同。触发自然界各个不同阶段之间过渡的因素几乎是未知的，但很显然，对这一过程的理解为有效预测花期复发，维持和下降提供了关键。浮游生物阶段构成大多数物种生命周期的短暂阶段，而抗性底栖阶段使物种能够长期承受不利条件，从而为最终的开花提供了休眠的水库，并促进了生物的扩散。在这里，我们回顾了当前在海水和微咸水域中主要的HAB生产者群体生命周期策略的知识。而不是进行全面的讨论，目的是强调一些研究里程碑，这些里程碑已经改变了我们对不同生命周期阶段的可塑性和频率以及它们之间的过渡的理解。我们还将讨论底栖和浮游形式的相关性及其对HAB动力学的影响。