Benthic-pelagic coupling and Cladophora problems in large lakes

自从斑马贻贝入侵五大湖以来，许多沿海地区都遭受了藻类过度生长的困扰。藻类被冲到海滩和海岸线上，污染了海滩和海岸线，这有效地阻止了娱乐用途。藻类还会中断冷却水和饮用水的供应，造成昂贵的损失，腐烂的草席还会滋生潜在的有害细菌。这些问题通常与关键营养物质磷含量过高有关，但湖泊中的磷浓度通常较低。我们将研究藻类是如何获得它们需要的磷而成为问题的，以及可能采取的管理措施。我们将利用安大略湖北岸的一段水域来检验这样一个理论：贻贝从水中收集磷，然后在接近湖底的地方以藻类可以利用的形式释放磷，从而促进藻类的生长。藻类和贻贝产量的测量将与三维模型相结合，这将使我们能够计算出当地磷源（例如雨水渠和下水道）对藻类问题的相对重要性。该模型将使我们能够预测潜在管理行动的有效性（例如，进一步减少全湖磷负荷），并估计补救行动的目标。这项工作还将增加我们对五大湖近岸生态的基本了解，因为它们继续经历生物入侵和其他压力。

Since the invasion of the Great Lakes by zebra mussels, many coastal areas have suffered from excessive growth of algae. The algae wash up on and foul beaches and shorelines, which effectively prevents recreational use. The algae also cause expensive interruptions to supplies of cooling and drinking water, and the decaying mats harbour potentially harmful bacteria. These problems would normally be associated with excessive levels of the key nutrient phosphorus, yet phosphorus concentrations in the lakes are generally low. We will undertake studies of how the algae manage to obtain the phosphorus they need to become a problem, and what management actions might be taken. We will use a section of the Lake Ontario north shore to test the theory that mussels enable the growth of algae by harvesting phosphorus from the water and then releasing it again near the bottom in a form the algae can use. Measurements of algal and mussel production will be combined with a three dimensional model that will allow us to calculate the relative importance of local phosphorus sources (e.g. storm drains and sewers) to the algal problem. The model will allow us to predict the effectiveness of potential management actions (e.g. further reductions in lake-wide phosphorus loading) and estimate targets for remedial action. The work will also increase our fundamental understanding of nearshore ecology in the Great Lakes as they continue to experience biological invasions and other stresses.