Effects of northern pike (Esox lucius) additions on pollutant accumulation and food web structure, as determined by 13 C and 15 N , in a eutrophic and an oligotrophic lake

In May 1993 and 1994, northern pike (Esox lucius) were added to eutrophic Lake 227 and oligotrophic Lake 110 at the Experimental Lakes Area in northwestern Ontario. Both lakes were previously dominated by cyprinids, and northern pike additions significantly decreased cyprinid densities in both lakes. Food web relationships were determined pre- and post-manipulation using stable carbon (δ 13