Check out my recent #JFB Editor's Choice: "Toxic tiddlers? Mechanisms driving within species mercury levels uncovered in anchovies ": https://doi.org/10.1111/jfb.70333 Dietary shift occurs in larger anchovies, which looks to facilitate their growth, but at the expense of increasing their mercury levels.
Paper by Chen et al https://doi.org/10.1111/jfb.70175