Isotopic study of contaminant biomagnification and fish growth in the St. Lawrence River food web

几个具有非常独特特征的水团组成了圣劳伦斯河（SLR）的淡水区。特别是，来自五大湖的富含碳酸盐的“绿色”水和来自渥太华河的“棕色”水从加拿大地盾中流出。这两种水直到经过靠近三河的圣皮埃尔湖时才大量混合。绿色和棕色的水在生产力、透明度和污染物负荷方面有所不同。我们将使用研究船Lampsilis，这是一个独特的平台，可以对SLR的浅水区域进行采样，我们将收集无脊椎动物和六种鱼类。最先进的技术，如稳定同位素分析和分子遗传学，将使我们能够识别生活在其中一个水域或不断在它们之间游动的鱼类的种类和年龄等级。我们将检验从同位素分析中推断出的与水质量的关系可以用来预测SLR鱼类中汞的浓度的假设，这是该生态系统中普遍存在的污染物。如果得到证实，这一结果将使我们能够根据水文数据对SLR中各种水团的污染物通量进行建模，从而从简单的生态变量（水文）预测复杂的生态变量（污染物浓度）。同样，我们将调查生活在不同水域的鱼类是否表现出不同的生长速度模式。

Several water masses with very distinctive characteristics make up the fresh-water section of the St. Lawrence River (SLR). In particular, carbonate-rich 'green' waters from the Great Lakes and the 'brown' waters from the Ottawa River draining the Canadian Shield stand out. These waters do not mix subtantially until they pass Lake Saint-Pierre, near Trois-Rivières. Green and brown waters differ in productivity, transparence, and contaminant loads. Using the research vessel Lampsilis, a unique platform to sample shallow areas of the SLR, we will collect invertebrates and six species of fish. State-of-the-art techniques such as stable isotope analysis and molecular genetics will allow us to identify fish species and age classes of fish that live in either one of the water masses or continually travel between them. We will test the hypothesis that affiliation to a water masse inferred from isotopic analyses can be used to predict concentration of mercury in fish of the SLR, a ubiquitous contaminant in this ecosystem. If confirmed, this result would then enable us to model contaminant fluxes from various water masses in the SLR from hydrological data, thus predicting a complex ecological variable (contaminant concentration) from a simple one (hydrology). Likewise, we will investigate if fish living in different water masses show different patterns in growth rate.