EXAMINING THE ROLE OF IRON IN PROMOTING CYANOBACTERIA DOMINANCE

富营养（富营养）湖泊中的蓝藻水华仍然是一个重大的全球性问题，包括加拿大，尽管数十年的科学研究和数十亿美元用于去除营养物以减少水华形成的风险。水华对环境健康构成威胁，因为许多菌株产生肝脏和神经毒素，它们会损害饮用沃茨的味道和气味。很明显，过量输入的营养物质，磷（P）的湖泊和河流是负责增加水生初级生产力和P是一个非常强大的风险因素水华形成和良性藻类的位移。然而，P导致富营养化沃茨中蓝藻水华的原因尚未明确。 此外，仅磷不能解释近年来在被认为是低风险的低磷水平湖泊中水华发生率的增加。 我的实验室最近的证据表明，铁的一种特殊形式，亚铁的可用性增加，促进了蓝藻对浮游植物（藻类）群落的主导地位，而且水华的时间受到物理和化学因素的影响，这些因素控制着亚铁从缺氧沉积物中的释放。该提案解决了新兴模型中关于P和铁如何共同作用以增加水华形成风险的几个知识空白。 它还审查了水华形成的发生率增加是否可能是气候变化的信号。

Cyanobacteria blooms in nutrient-rich (eutrophic) lakes remain a significant global problem including Canada, in spite of decades of scientific research and billions of dollars spent on nutrient removal to reduce the risk of bloom formation. Blooms pose a threat to environmental health because many strains produce liver and nerve toxins and they can impair the taste and odour of drinking waters. It is clear that excessive input of the nutrient, phosphorus (P) to lakes and rivers is responsible for increased aquatic primary productivity and that P is a very strong risk factor for bloom formation and displacement of benign algal species. However, the reason why P leads to blooms of cyanobacteria in eutrophic waters has not been clearly established. In addition, P alone does not explain increasing incidence of blooms in recent years in lakes with low P levels that were considered to be at low risk. Recent evidence from my lab shows that increased availability of a particular form of iron, ferrous iron, promotes dominance of phytoplankton (algal) communities by cyanobacteria and that the timing of blooms is influenced by physical and chemical factors that control release of ferrous iron from oxygen-depleted sediments. This proposal addresses several knowledge gaps in the emerging model about how P and iron work together to increase the risk of bloom formation. It also examines whether increasing incidence of bloom formation may be a climate change signal.