translate English to French: The basic conclusion is that Lake Erie has exhibited mesotrophic to eutrophic conditions, at least in parts, since approximately 1850, and that the initial disturbance to the lake's metabolism was the most important one.
La conclusion fondamentale est que le lac Érié montre, depuis environ 1850, des conditions allant de méso à eutrophes, du moins en partie, et que la perturbation initiale du métabolisme du lac a été la plus importante.