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

几个具有鲜明特征的水团构成了圣劳伦斯河(SLR)的淡水部分。尤其是来自五大湖富含碳酸盐的“绿色”水域和来自渥太华河排干加拿大盾的“棕色”水域显得尤为突出。在经过特里斯-里维耶尔附近的圣皮尔湖之前，这些水不会巧妙地混合在一起。绿色水域和棕色水域在生产力、透明度和污染物负荷方面存在差异。利用研究船Lampsilis，一个独特的平台对SLR的浅海区域进行采样，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团中或持续在其中一个水团中生活的鱼类种类和年龄类别。我们将测试这样一个假设，即从同位素分析推断的水团的从属关系可以用来预测SLR鱼类中汞的浓度，SLR是这个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从水文数据中模拟SLR中不同水团的污染物通量，从而从简单的生态变量(水文学)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团中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.